Recycling Excess Heat From the Data Center

← Back to Stories (view on slashdot.org)

Recycling Excess Heat From the Data Center

Posted by kdawson on Tuesday December 1, 2009 @07:14AM from the talkin'-'bout-my-generation dept.

itwbennett writes "A new data center being built in Helsinki, scheduled to go live at the end of January, will generate energy and deliver hot water for the city. The data center is located in an old bomb shelter and is connected to the Helsinki public energy company's district heating system, which works by pumping boiling water through a system of pipes to households in Helsinki. The recycled heat from the data center could add about 1 percent to the total energy generated by the energy company's system in the summer." The article doesn't say what the overall efficiency of the heat recovery is. Researchers at MIT are working on a new energy-conversion technology based on quantum dots that they say has already demonstrated 40% of the Carnot efficiency limit — 4 times what is achieved by current commercial thermoelectric devices. The researchers believe they can reach 90% of the Carnot limit.

121 comments

Min score:

Reason:

Sort:

WTF, why is a Carnot reference here? by ElSupreme · 2009-12-01 07:18 · Score: 3, Insightful

How is the Carnot cycle apply here? This is direct heat conversion, and the efficiency should be near 100%, you would have line losses.

--
My addiction: Arguing with idiots. AKA Slashdot!
1. Re:WTF, why is a Carnot reference here? by Anonymous Coward · 2009-12-01 07:35 · Score: 0
  
  Because you need a cycle to extract the waste heat. Lookup Organic Rankine Cycle.
2. Re:WTF, why is a Carnot reference here? by vlm · 2009-12-01 07:50 · Score: 3, Informative
  
  How is the Carnot cycle apply here? This is direct heat conversion, and the efficiency should be near 100%, you would have line losses.
  Reading thru a filter of journalist ignorance, I think the journalist is trying to say they're using a heat pump to reject the heat from the cooling system into the heating system's boiling water. There is a Carnot cycle limit to heat pumps.
  
  --
  "Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
3. Re:WTF, why is a Carnot reference here? by The+Archon+V2.0 · 2009-12-01 07:54 · Score: 1
  
  Why is a Carnot reference here? Probably because there's not that many publications with user forums where you can mention a thermodynamic cycle in the first paragraph and get back responses more coherent than "I saw Lance Armstrong riding one of those!"
4. Re:WTF, why is a Carnot reference here? by ElSupreme · 2009-12-01 08:04 · Score: 1
  
  Yeah but all the efficiency/carnot losses end up in the hot water.
  
  --
  My addiction: Arguing with idiots. AKA Slashdot!
5. Re:WTF, why is a Carnot reference here? by jank1887 · 2009-12-01 08:11 · Score: 4, Informative
  
  because the summary is talking about two entirely separate topics. (1) Helsinki data center will deliver waste heat in useful form to the city. (2)Researchers at MIT are working on a solid state heat-to-electric conversion element called a thermoelectric device. current devices are at best ~10% of Carnot (practical devices approach 10% total efficiency on a good day), and they say they'll hit 40-90% of carnot with their new quantum dot TEG's. We'll see.
  You are correct, though. Carnot efficiency discussion only really applies to (2) not (1). Mister itwbennett just decided to lump these two things into one submission.
6. Re:WTF, why is a Carnot reference here? by MillionthMonkey · 2009-12-01 08:23 · Score: 1
  
  You're taking conservation of energy into account, but you're forgetting entropy. Think about it... do you really suppose, even in theory, that you could pump electricity into a datacenter, put pretty pictures on people's screens all over the world, and then pick up 100% of that electricity back for use in heating your hot water? As if the electricity were merely waving "Hi" to the datacenter on its way to this water being boiled?
  
  You can shorten the line to as much as you want. Assume no energy is lost to heat in the transmission lines. You'd still have a heat loss problem near the datacenter and whatever heat reclamation gizmo it's using. The max efficiency that can be extracted from a heat engine is 1-(Tc/Th) where Tc and Th are the absolute temperatures of the inside and outside in Kelvin. And 1-(273 / 300) = 0.1 or 10%. Meaning that (assuming it's freezing outside and 27 degrees C in the datacenter), 10% of the electrical power going to the datacenter could be reclaimed, in theory, if they were to extract all the energy that went into heating it from freezing (so the datacenter is freezing again). They're proud of themselves for getting 40% of that or 4%.
  
  The rest of that energy goes toward warming the great outdoors which is at Tc. The Swedes have an advantage being so far North, but if they were to move their datacenter inside the Large Hadron Collider- or if they were to move the population of Sweden into the datacenter- your post would have more merit.
7. Re:WTF, why is a Carnot reference here? by ElSupreme · 2009-12-01 08:38 · Score: 1
  
  You are looking at all of this to complexly. Carnot cycles are for calculating heat engines. This is not a heat engine. There is NO WORK being done.
  
  I put electricity into a chip. The chip uses X amount of energy and ~100% of the (electrical) energy is converted to heat energy.
  
  If I run water over the chips (lets assume fully submerged for simplicity) and maintain their temperature at 20 degC. ~100% of the heat is removed by the water.
  
  I realize there are line losses in the electrical wires. There are heat losses from the pipes piping away the heat. There are also radiation losses in the form of light and other waves that transmit through the water.
  
  But anyway a heat exchanger (properly and sufficiently sized) should be near 100% (~97%-98%) efficient.
  
  Now when you use a heat pump cycle you start loosing efficiency, but it is again almost 100% loss of heat, which goes to the hot water loop.
  
  I would imagine that such a system is ~90%+ efficient from electrical energy (going to all items being recovered) and the heat pump cycle.
  
  You need to ask yourself how and where does the energy go if it doesn't end up in the hot water loop?
  
  --
  My addiction: Arguing with idiots. AKA Slashdot!
8. Re:WTF, why is a Carnot reference here? by halcyon1234 · 2009-12-01 08:55 · Score: 1
  
  Yo Carnot have 100% efficiency, coptain. It's just nout possible!
  
  --
  UTF-8: There and Back Again
9. Re:WTF, why is a Carnot reference here? by Snufu · 2009-12-01 09:19 · Score: 2, Informative
  
  The summary writer may also have wanted to suggest that thermoelectric devices may be used to convert the waste heat at the data center into useful energy. However, thermoelectric devices are not really feasible for this application. To achieve the efficiencies cited for thermoelectric technologies, you need temperature gradients in the 100's degrees C, as in, for example, a car engine. Typical temperature gradients at data centers are on the order of tens of degrees C. This is considered "low-grade" heat in the renewable energy vernacular.
10. Re:WTF, why is a Carnot reference here? by Smidge204 · 2009-12-01 09:26 · Score: 1
  
  And this is exactly why heat pumps are not rated by efficiency but by coefficient of performance (COP).
  Of course nobody seems to have noticed that the 40% claim is completely unrelated to the headline story and seems to have been needlessly tacked on by the editor.
  =Smidge=
11. Re:WTF, why is a Carnot reference here? by pookie13 · 2009-12-01 09:49 · Score: 1
  
  The Swedes have an advantage being so far North, but if they were to move their datacenter inside the Large Hadron Collider- or if they were to move the population of Sweden into the datacenter- your post would have more merit.
  Sweden? Last time I checked, Helsinki was still in Finland. And no. We Finns wouldn't like the idea of 9.3 million more Swedes in Helsinki.
12. Re:WTF, why is a Carnot reference here? by MillionthMonkey · 2009-12-01 10:06 · Score: 2, Interesting
  
  We've both made errors. I made a reference to "Swedes" and not Finns because I read too fast. However, you said:
  
  Carnot cycles are for calculating heat engines. This is not a heat engine. There is NO WORK being done.
  
  First of all theoretical efficiency limits apply to both types of reversible heat engines- steam engines which extract work and heat pumps (e.g. air conditioners) which require it. (In the heat pump case I guess Th would still be a temperature in the datacenter somewhere, but Tc would now be their hot water heaters' temperatures, not the temperature outside- another mistake I made. These Finns are confusing.) But RTFA- this looks like a heat engine:
  
  Helsinki public energy company Helsingin Energia will recycle heat from a new data center to help generate energy and deliver hot water for the Finnish capital city, it said on Monday.
  The recycled heat from the data center, being built by IT and telecom services company Academica, could add about 1 percent to the total energy generated by Helsingin Energia's system in the summer, according to Juha Sipilä, project manager at Helsingin Energia.
  You DO have more to stand on here if the water were flowing (say) into some hot water heater before being heated to a desired temperature, so the heater would has less work to do- but what's this then in your post about "transmission lines"? It's clear that work is being done here if they're generating electricity in the summer.
  
  I put electricity into a chip. The chip uses X amount of energy and ~100% of the (electrical) energy is converted to heat energy.
  
  Yes that's conservation of energy. But notice that the energy has been converted into a less useful form, even if the flow goes directly off that chip into someone's bathwater. There isn't enough water being heated by that chip, or if there is, it's too cold for anyone to notice. Finns want water to come out of their hot water faucets at temperatures greater than if it were just pumped through datacenters.
  
  If I run water over the chips (lets assume fully submerged for simplicity) and maintain their temperature at 20 degC. ~100% of the heat is removed by the water.
  
  Whoa whoa slow down there, Tex. You're still thinking in terms of conservation of energy. But there are entropy losses- how will you maintain the temperature at 20 deg C unless you're pumping loads of water across the chip- so much that the heat is dissipated across a volume of water too large to make any difference? Or if you're not- say you pump a low flow across the chip so it maintains a temperature at 30 deg C. A heat engine running on that potential difference (back to generating electricity for transmitting over these transmission lines) you won't be able to extract all the electrical energy that you needed to run the chip. Most of it will heat the great outdoors. But that's not what's going on- either in the article, or an imagined situation involving generation of electricity to go across power lines.
  
  I realize there are line losses in the electrical wires. There are heat losses from the pipes piping away the heat. There are also radiation losses in the form of light and other waves that transmit through the water.
  
  Yes yes I realize that too, but we're both waving that stuff away.
13. Re:WTF, why is a Carnot reference here? by MillionthMonkey · 2009-12-01 10:29 · Score: 2, Interesting
  
  Yeah I read too fast. Although when I was a kid I used to have a Finnish pen pal in Turku. She stopped writing.
14. Re:WTF, why is a Carnot reference here? by Intron · 2009-12-01 10:46 · Score: 1
  
  The system I liked was the guy who cut the big hole in his kitchen wall. In winter he puts the insulated board in front. In the summer he pushes the back of his refrigerator through to the outside so its exhaust heat doesn't end up in his kitchen. Cuts his A/C bill enough to be noticeable and takes less than one roll of duct tape per year.
  
  --
  Intron: the portion of DNA which expresses nothing useful.
15. Re:WTF, why is a Carnot reference here? by ElSupreme · 2009-12-01 11:08 · Score: 1
  
  Ok so as a mechanical engineer that does this stuff for a living here is how you would design such a system.
  
  You design a cooling loop of water that cools the data center. You pump water fast enough to remove the amount of heat generated by the data center, and maintain a certain liquid temperature, which will translate to a certain chip temperature.
  This water say enters the data center at 20C and leaves at 50C, you can change the temperatures of these by adjusting the flow rate of water (assuming a constant chip loading, in reality this flow rate will change based on temperature probes).
  You dump the 50C water into a tank (heat storage vessel, think of it as a battery for heat). You then take this 50C water into a heat pump, this is reversible and such follows carnot cycle laws. This chills water back to 20C (and ready to cool processors), by heating a refridgerant, the refridgerant then heats your hot water city loop, with all the carnot losses ending up as heat in the refridgerant (losses get conserved and used). All your losses end up being used, as they are in the form of heat, and you are collecting WASTE heat.
  
  The reason why your AC unit has to be outside is because of this, the losses incured would end up heating your house instead of cooling it.
  
  Now on to your claims. There is NO reference to a heat engine, or anything that would require knowledge of a Carnot cycle. Thinking about how I would attain higher temperatures you would employ a heatpump (but this pump would contribute ~95%+ of its losses to heat the final fluid).
  Ok so keeping chips at 20C isn't realistic, it should be more like 50C. Doing this would rais the efficency of the heat pump required to get higher temperatures. BUT ALL the HEAT would STILL be RECOVERED!
  And I am sorry but you will recover (assuming chip surrounded by your heat recovery fluid) near 100% of the energy used. This is because near 100% of the energy used by processors is converted to heat. There is no way for the heat to get 'outdoors' if it is surrounded by a fluid. All the heat must pass to the fluid before it goes anywhere else.
  And it is also worth noting that 'losses' in a carnot engine are almost purely heat. When you are trying to heat something you get to keep all your heat, it is not lost. Say you have 10kW of waste heat, and your heat pump is 1kW. You will put out 11kW of heat. If your heat pump is 10kW you will put out 20kW (10 + 10) of heat. Both ways you still recover the entire 10kW, and if you need more heat anyway then the effiecency is a moot point (in reality it is relevent because it is cheaper to heat water with natural gas, than electricity).
  
  --
  My addiction: Arguing with idiots. AKA Slashdot!
16. Re:WTF, why is a Carnot reference here? by mosb1000 · 2009-12-01 11:14 · Score: 1
  
  "do you really suppose, even in theory, that you could pump electricity into a datacenter, put pretty pictures on people's screens all over the world, and then pick up 100% of that electricity back for use in heating your hot water?"
  
  Yes. Where do you think the energy goes? The first law of thermodynamics requires that you get it all back.
17. Re:WTF, why is a Carnot reference here? by daremonai · 2009-12-01 11:22 · Score: 2, Funny
  
  There is NO WORK being done.
  You know way too much about computers.
18. Re:WTF, why is a Carnot reference here? by MillionthMonkey · 2009-12-01 11:36 · Score: 1
  
  Wow I'm too tired to read all that. Actually RTFA more closely I think you win, if by "transmission lines" you meant water pipes and not wires and their intention is to reclaim the energy in a disordered form of heat instead of electricity. The article mostly talks about how they're going to "generate energy" which doesn't make it clear.
  (But psst... there is no "d" in "refrigerant".)
19. Re:WTF, why is a Carnot reference here? by MillionthMonkey · 2009-12-01 11:42 · Score: 1
  
  Yeah but what I meant when I said "pick up 100% of that electricity back" was getting all the power back in the form of electricity before the end users convert it to heat again. I didn't RTFA carefully enough and pictured the wrong scene when he said "transmission lines".
20. Re:WTF, why is a Carnot reference here? by Anonymous Coward · 2009-12-01 14:47 · Score: 0
  
  Because the temperature at which the "heat" comes out of a data centre is simply not high enough to use it for most practical purposes so the temperature has to be increased. From the Helsinki article "The pump is also very efficient -- you get five times the amount of energy you put in, he said" so the data centre is using a technology similar to ground source heat pumps with the district heating system as the sink. The problem with the efficiency claims here is that they are spending more electrical power to recover the heat from the data centre which doesn't need any air conditioning to start with due to it's location in Helsinki. Electrical power tends to be an inefficient way to heat things because the heat - electricity conversion is normally less than 40% efficient whereas if you delivered that heat directly to the heating system....
  So if we take the waste heat from the data centre they are recovering 4 units of heat for each unit of energy it consumes, we have, say 3 units of heat being converted to 1 unit of electricity for the data centre to use, we recover that 1 unit and add 0.25 units of electrical power (that is derived from 0.75 units of heat) to run the pump and we extract 1.25 units of heat for the district heating system out of 3.75 units of heat consumed by the system. No laws of entropy broken and no magic taking place.
  There is a theoretical "saving" here of 0.5 units of heat out of every 3.75 assuming they achieve peak efficiency and have no losses elsewhere. There is no "data centres use 50% of their power in cooling, we are more efficient" argument because they need to be compared with what would be built now and not some out of date design.
  I would rather see them spend the time and effort writing slightly more efficient software that didn't need quite so many servers.
21. Re:WTF, why is a Carnot reference here? by Falconhell · 2009-12-01 15:47 · Score: 1
  
  I just did the same thing for my caravan
  to help out the aircon.
22. Re:WTF, why is a Carnot reference here? by pookie13 · 2009-12-01 19:46 · Score: 2, Insightful
  
  Yeah I read too fast. Although when I was a kid I used to have a Finnish pen pal in Turku. She stopped writing.
  No wonder she stopped writing if you thought that Helsinki is in Sweden. We do have a hate / love relationship with the Swedes.
23. Re:WTF, why is a Carnot reference here? by Anonymous Coward · 2009-12-01 21:58 · Score: 0
  
  A heat exchanger is not 100% efficient unless the size of the exchanger is huge but then thgere are hydraulic loading limits...
  Realistically if the chips are at say 100C the exchanger will be able to heat its water stream up to around 90-95C.
  On the other side at the house the heat exchanger there (i.e. radiator) will be able to cool this down water to 35C (assuming ambient air conditions of 20C).
  Therefire losses are 5-10C on one side and 15C on the other side. To convert this to a power rating you need the mass flow of the water stream.
24. Re:WTF, why is a Carnot reference here? by BOFHelsinki · 2009-12-02 07:52 · Score: 1
  
  Love / hate is just the beginning for a meaningful, fulfilling relationship...
25. Re:WTF, why is a Carnot reference here? by AigariusDebian · 2009-12-05 03:05 · Score: 1
  
  Or make it much simpler - city heating systems need a water inlet to compensate for lost water in lines and for hot water usage by the people. Instead of taking cold water (at 20C) from the cold water system, the water is first piped trough a data center where it get heated up to 50C, so the city heating system needs less heat to heat this water to the 95C it uses in its circulation. That's it - simple and almost 100% efficient.
26. Re:WTF, why is a Carnot reference here? by AigariusDebian · 2009-12-05 03:09 · Score: 1
  
  Not much of the power leaves the actual datacenter building. If you think about it, the only useful energy leaving the datacenter is a few volts in the Ethernet cable or a bunch of photons the the optical data line. The rest of the electricity that the datacenter uses is convereted into heat each time a memory cell is reset to the resting state via the flush resistor and such.
I think it's great, but... by natehoy · 2009-12-01 07:18 · Score: 3, Insightful

Is pumping boiling water through pipes the most efficient way to heat houses? Isn't there a pretty massive heat loss in the pipes?
Having said that, if they are already using this system for heat, the introduction of waste heat from a datacenter seems to make a lot of sense. Acts as a heat sink for the data center, reduces the amount of energy needed to heat the water.

--
"This post contains words, known to the State of California to cause thought. Wash brain thoroughly after reading."
1. Re:I think it's great, but... by ElSupreme · 2009-12-01 07:22 · Score: 1
  
  Well it can be fairly efficient. http://en.wikipedia.org/wiki/Floor_heating#Efficiency
  The main benifit is that you can easily recover waste heat. From power plants, or any other large heat source.
  
  And with proper insulation you can limit your heat losses.
  
  --
  My addiction: Arguing with idiots. AKA Slashdot!
2. Re:I think it's great, but... by Anonymous Coward · 2009-12-01 07:24 · Score: 0
  
  Is pumping boiling water through pipes the most efficient way to heat houses? Isn't there a pretty massive heat loss in the pipes?
  Presumably these pipes are insulated, and/or buried. And it is quite common for large buildings or campuses to use hot water with a central boiler for heat distribution.
  In fact, many cities do that for heating & cooling:
  http://en.wikipedia.org/wiki/District_heating
3. Re:I think it's great, but... by onionman · 2009-12-01 07:24 · Score: 4, Informative
  
  Is pumping boiling water through pipes the most efficient way to heat houses? Isn't there a pretty massive heat loss in the pipes?
  Having said that, if they are already using this system for heat, the introduction of waste heat from a datacenter seems to make a lot of sense. Acts as a heat sink for the data center, reduces the amount of energy needed to heat the water.
  Actually, it's a reasonable system for heating large building complexes where a central facility can heat the water. Many Universities and large corporate complexes already use similar methods for heating their campuses. Insulation on the pipes keeps the water warm in transit. These complexes can also cool their buildings in the summer by pumping chilled water through the system.
4. Re:I think it's great, but... by Anonymous Coward · 2009-12-01 07:33 · Score: 0
  
  On its own it isn't the most efficient system, but these systems are typically build to make use of waste heat produced by electricity plants or heavy industries, thus increasing overall energy efficiency.
5. Re:I think it's great, but... by sfcat · 2009-12-01 07:39 · Score: 4, Insightful
  
  Yes and no, water actually is a very good "thermal" battery. That is why coastal regions have a more temperate climate than inland region. Its cheap and we know a lot about how to move it around and have existing infrastructure for doing exactly that. Its not the most efficient way, but often it is the most practical and economical.
  
  --
  "Those that start by burning books, will end by burning men."
6. Re:I think it's great, but... by amorsen · 2009-12-01 07:42 · Score: 1
  
  It's fairly common in Northern Europe (excepting England, for some reason). Losses aren't very high because the pipes are insulated. In modern systems the water isn't boiling, but it will take a long time before everything has been converted to lower temperature systems.
  You can get extremely efficient by using low-temperature (30C or lower) remote heating plus a heat pump, but that means a large investment per house or apartment block.
  
  --
  Finally! A year of moderation! Ready for 2019?
7. Re:I think it's great, but... by Cyberax · 2009-12-01 07:44 · Score: 1
  
  Usually, district heating uses waste heat from power plants. It'll be wasted anyway, so why not use it to heat houses?
8. Re:I think it's great, but... by Anonymous Coward · 2009-12-01 07:53 · Score: 0
  
  It is very efficient if central planning is politically feasible option in the region, population density is high enough (town or city consists of relatively uniform area with apartment blocks) and there's actual need for heating. In Helsinki area virtually all apartment buildings use the system - practically only problems that can occur are overloading of the power plants on extremely cold weather... and much more commonly, skimpy apartment block landlords not turning the house valves quick enough to keep in pace with cooling weather when winter approaches. As insulation tends to be much more reasonable than many other Europeans seem to use, cold temperatures (15 degrees C) are almost unheard of even on worst situations...
9. Re:I think it's great, but... by Idiomatick · 2009-12-01 08:01 · Score: 1
  
  It is actually decently efficient.
  
  However, the cost of installing these systems is often costly. Since pipes obviously cost much more than water. For a good example we can look on a smaller scale. Many houses and buildings built 50+ years ago had cast iron radiators. We don't use them anymore because they are expensive as fuck to install and maintenance is more expensive. But overall efficiency is similar and in some cases better than present day systems.
  
  So I would guess it is a system already in place from older times. That or it is in a situation where it is still worth it over newer tech.
10. Re:I think it's great, but... by vertinox · 2009-12-01 08:23 · Score: 2, Insightful
  
  Its not the most efficient way, but often it is the most practical and economical.
  Also, if the pipe breaks, then its not really that bad of a cleanup.
  
  --
  "I am the king of the Romans, and am superior to rules of grammar!"
  -Sigismund, Holy Roman Emperor (1368-1437)
11. Re:I think it's great, but... by DerekLyons · 2009-12-01 09:07 · Score: 1
  
  Actually, it's a reasonable system for heating large building complexes where a central facility can heat the water. Many Universities and large corporate complexes already use similar methods for heating their campuses.
  'Already' is a bit misleading however - central heating installations like these, using steam or hot water, go back over a century - New York's dates from 1880.
  
  These complexes can also cool their buildings in the summer by pumping chilled water through the system.
  Or they can use hot water to drive absorption chillers, or steam to drive turbine centrifugal chillers.
12. Re:I think it's great, but... by pla · 2009-12-01 09:14 · Score: 1
  
  In modern systems the water isn't boiling, but it will take a long time before everything has been converted to lower temperature systems.
  
  Not to say that lower-temp systems don't exist (I can see the appeal in single-building residential systems in particular), but I'd point out that virtually all non-residential heating loops don't actually carry water they carry steam (at least on the efferent lines). They do so for the simple reason that steam-at-100C carries 3-5x the energy of water-at-100C (depending on the return temperature, of course) and also has a lower thermal conductivity (so lower unintentional losses on the way).
  
  Additionally, using a steam to water conversion has the bonus that you don't actually need any explicit pumps - Valves in the line ensure that the steam pushes itself out via high-pressure, and the phase change causes low pressure on the return side. You really couldn't ask for a more convenient arrangement.
  
  So I would certainly say that it will take a long time to get people to switch over, since doing so makes the system drastically less efficient, more complicated, and less reliable as a whole.
13. Re:I think it's great, but... by sjames · 2009-12-01 09:28 · Score: 2, Interesting
  
  It depends on the priorities and the source of the heat. Steam turbines have a considerable load of waste heat that has to be dumped somewhere. No sense heating a lake if it can heat homes instead. Since it is waste heat, the efficiency hardly matters, any usefulness beats the alternative.
  In other cases the choice is between many small boilers or one big one with exhaust scrubbers and more complete combustion. With good pipe insulation that can be a win.
14. Re:I think it's great, but... by jo_ham · 2009-12-01 09:53 · Score: 1
  
  What do you mean "excepting England" - almost all houses here have central heating based on water-filled radiators. I'm having to think very hard about the last house I visited here that *didn't* have a piped water heating system.
  The water isn't usually boiling though, since the systems are almost always open circuit (so not pressurised). The one in my house uses water at about 60C, and also provides hot water for the tank for showers/dishes etc. I don't have a combi, so if you want hot water, you have to switch it on ahead of time, unless you set timers and so on, which I don't bother with.
15. Re:I think it's great, but... by Anonymous Coward · 2009-12-01 10:20 · Score: 0
  
  1) The pipes have some 4" of polyurethane insulation and they are buried 4-6 feet underground
  2) the heat used in the district heating systems is excess heat from coal/natural gas/wood burning powerplants that primarily generate electricity
  So all in all, the district heating system is not too bad. It does have the downside that there is only one provider per area (your local power utility), so once you have joined the system you have to take any pricing changes they decide to make.
16. Re:I think it's great, but... by DavMz · 2009-12-01 10:40 · Score: 1
  
  I know for sure it is used in France in houses especially when heating is through the floor. I have also seen the hot water underfloor heating Efficiency of underfloor heating isn't bad: if you have good insulation below the pipes, you don't loose too much heat through the ground; as the floor is warm, convection occurs naturally and the room temperature gets more uniform; you don't have the "cold feet" effect which makes you heat more (remember, no shoes inside the house).
  Quoting Wikipedia: "Warm water UFH is 30% more efficient than low temperature radiators with a ground source heat pump, 20% more efficienct with an air source heat pump, and 5-15% more efficient than low temp radiators with a condensing boiler, according to a major study produced by EU-RAY, the European Radiant Heating & Cooling Association."
  In France, you can also find hot water heating in habitation buildings, where you have one heater for all the appartments, and I think that similar system is used in the Russia (or at least it used to be).
17. Re:I think it's great, but... by discomike · 2009-12-01 11:12 · Score: 1
  
  He's not talking about distribution inside your house from a central heating point, but for distribution to your house from a central heating point in the city. Like here in Gothenburg(pop ~0,75 million). Total heating capacity for the central system here is a bit over 2000MW, our (clean*)garbage power plant provides 28% of the city's heating & hot water, and 5% of electricity needs. Among other providers is a biogas furnace from the sewage treatment plant, waste heat from industries like refineries, and Volvo, also about 150MW is recovered with heat exchange from the sewage. About 80% of the heat provided used to be waste in some form. *meets future EU-demands on cleaning. First electro filter, then wet cleaning which removes particles and condenses acid gases, then a textile filter which removes almost all dioxin and most of the sulfur.
18. Re:I think it's great, but... by smoker2 · 2009-12-01 11:15 · Score: 1
  
  He meant, they aren't connected to a large facility that sends hot water their way, which they aren't. It's really not difficult if you just read the whole summary.
19. Re:I think it's great, but... by jo_ham · 2009-12-01 11:32 · Score: 1
  
  I well understood the summary (and the FA), but "sending hot water around liquid filled radiators" is a very popular method of heating your home in England, centralised distribution or not.
  There are examples of centralised distribution here - mostly pilot projects, since the infrastructure for houses is already here and well understood - ie, liquid pipes and metal radiators, so conversion to centralised systems is simplified.
  It's really much easier if you don't misinterpret what I say and apply your own meaning.
20. Re:I think it's great, but... by amorsen · 2009-12-01 20:26 · Score: 1
  
  but I'd point out that virtually all non-residential heating loops don't actually carry water they carry steam
  Not around here (Denmark) they don't. Steam used to be popular, but it's a waste of energy which could be used to make electricity.
  But as I said, not everything has been converted yet.
  
  --
  Finally! A year of moderation! Ready for 2019?
21. Re:I think it's great, but... by amorsen · 2009-12-01 20:48 · Score: 1
  
  Ok, from the original post:
  
  Is pumping boiling water through pipes the most efficient way to heat houses? Isn't there a pretty massive heat loss in the pipes?
  I think it's obvious that the original poster meant remote heating. The original article is about remote heating. I was certainly talking about remote heating.
  You're the only one who is talking about how to get heat transported around inside the house.
  England is stuck with a lot of antiquated systems where electricity is turned into heat without a heat pump. You pretty much can't do worse than that, thermodynamically.
  
  --
  Finally! A year of moderation! Ready for 2019?
22. Re:I think it's great, but... by dkf · 2009-12-01 22:39 · Score: 1
  
  [District heating is] fairly common in Northern Europe (excepting England, for some reason).
  It's usually used for industrial purposes in England rather than domestic or commercial. Part of this is due to the fact that large power plants tend to be located well outside cities (as an anti-pollution measure and because land values out in the boonies are lower).
  
  --
  "Little does he know, but there is no 'I' in 'Idiot'!"
23. Re:I think it's great, but... by xaxa · 2009-12-01 22:55 · Score: 1
  
  I've never seen a normal house with district heating in England, only university campuses (and presumably similarly structured settlements, like hospitals). Wikipedia says "Though they are said to be efficient, a frequent complaint of residents is that the heating levels are often set too high - the original designs did not allow for individual users to have their own thermostats." -- that's something I've heard before, and would fit with English people deciding they don't like something and rejecting it rather than improving it </bitter>.
  Also "Negative influence in The Netherlands (3% use) and UK (1%) can be attributed partially to milder climate and also competition from natural gas supply."
  Cheap homes in England/Wales (not sure about the rest of the UK, IANAL) are often built with the cheapest possible heating -- i.e. resistive electric heaters -- because installing better heating isn't required by law/regulation as is the case elsewhere.
24. Re:I think it's great, but... by Anonymous Coward · 2009-12-01 23:32 · Score: 0
  
  The thing is this works in so many dimensions. True there are losses. But theres also losses in local heating, electricity etc.
  The real benefits are:
  1) its much more efficient to have one big heat plant than each house having its own.
  2) When you produce electricity you get exess heat anyways. So what we are doing is using the heat excess of the energy production. Ok sure so helsinki is nearly the 60th parallel. So at the very core of winter they do produce more heat than electricity, but on teh whole it evens out.
  3) the system is extraordinarily reliable. Personally i have for whole of my life lived in a house with this heating system and to this day i have never ever encountered a loss of heating.
  4) the that is not directly connected into your home. The energy networks pipes are a closed system so you use that in your boiler room to heat water to say 60 degrees and use that to heat the appartment.
  5) yes there are losses you can clearly see where the heat mains go when the temperature is at just below freezing. Its still more cost and energy effective tough than electric or oil. And during summer the same system can transport cold if need be.
25. Re:I think it's great, but... by moosesocks · 2009-12-02 02:29 · Score: 1
  
  A (very) large portion of Manhattan is heated via a central steam system. It's incredibly efficient, and is also the reason why almost no NYC buildings have noticeable smokestacks, and why the city was actually quite clean until the rise of the automobile. By concentrating the coal burning into a few points (5 IIRC), pollution in the city was greatly reduced.
  On a somewhat more scary note, thanks to decades of neglect, many of the original pipes are still in use, carrying high-pressure steam. Failures are pretty spectacular...
  
  --
  -- If you try to fail and succeed, which have you done? - Uli's moose
26. Re:I think it's great, but... by Tug3 · 2009-12-02 05:22 · Score: 1
  
  Naturally there will always be energy loss when you tranport energy.
  But this system is pretty well suited for cities. And naturally the pipes are well insulated and laid under ground to keep ambient temperature constant.
  The water is heated at the plant (or the data center in this case) then pumped to the system. The system consists of main lines usually running under streets. These have smaller lines going to a connected building. Inside the building the pipes go to a "boiler room" or heat center or what-ever you want to call it. There the heat is transferred from the system to buildings own heating system. Usually the heating system consists of hot water running in pipes as well. Although for safety the temperature is much lower on the building's own system. Also the heat from the system may be used to heat your tap water.
  In Finland gas furnaces are almost non existent and only used for camper vans or trailers used for vacations during colder seasons. In the cities this kind of centralised heating is popular due to the efficiency. Both economic and energy. In rural areas oil and electricity are most popular, but heat-exchangers are catching up. Wether it be pumping heat out of outside air or the ground, both work well and give free energy to the house owner. Solar or wind are not harnessed in Finland due more to political reasons than anything else.
  
  --
  If all else fails, pull the plug and get out...
  The Life is out there...
27. Re:I think it's great, but... by Anonymous Coward · 2009-12-02 06:00 · Score: 0
  
  Since the heating pipes carry huge amounts of water near boiling point, a pipe break can be pretty dangerous.
28. Re:I think it's great, but... by amorsen · 2009-12-02 08:55 · Score: 1
  
  True, you need the power plants fairly close to the consumers, which can be a problem. Especially in England with plenty of rivers for cooling, so the power plants haven't been forced to be placed where people live.
  
  --
  Finally! A year of moderation! Ready for 2019?
29. Re:I think it's great, but... by Anonymous Coward · 2009-12-03 23:02 · Score: 0
  
  You'd think so, but a broken water pipe recently flooded Helsinki's main subway station so badly that it'll be closed for months and take millions to repair. An elevator shaft burst from the pressure, and the escalators are ruined.
  Although to be fair, it would have been a non-issue if someone hadn't drilled a hole in the protective barrier. Human error aside, you are 100% correct.
30. Re:I think it's great, but... by AigariusDebian · 2009-12-05 03:17 · Score: 1
  
  Not in Eastern Europe - all ex-soviet systems are hot water based without any steam.
The problem with approaching Carnot efficiency... by gyepi · 2009-12-01 07:20 · Score: 1

... is that the process will take longer and longer time. Carnot efficiency is defined by the efficiency of a reversible heat engine operating between the given temperatures; but truly reversible processes would take infinite amount of time. Efficiency is certainly an important aim, but certainly not the solely desirable aim.

--
Attitudes make the difference between Space and Time: we want to MAX our temporal, and MIN our spatial extension.
It works well in cities. by FatSean · 2009-12-01 07:22 · Score: 1

Sure, you do get some loss but the simplicity and reliability of these system is quite impressive. I suppose they could always get extra-big pipe wrap :)

--
Blar.
1. Re:It works well in cities. by zippthorne · 2009-12-01 07:52 · Score: 1
  
  Well, they have to be, because you're basically threading a steam bomb throughout your entire house. I'll stick with forced air thank you.
  
  --
  Can you be Even More Awesome?!
2. Re:It works well in cities. by FatSean · 2009-12-01 07:58 · Score: 1
  
  Ew, forced air? What a pain that is. I'm all about radiant hot water heat these days. You don't have to worry about mold and pathogens in your ductwork.
  
  --
  Blar.
3. Re:It works well in cities. by vlm · 2009-12-01 08:04 · Score: 1
  
  I'm all about radiant hot water heat these days. You don't have to worry about mold
  Until it starts leaking. Then you have cold, and mold.
  
  --
  "Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
4. Re:It works well in cities. by FatSean · 2009-12-01 08:07 · Score: 1
  
  Well the baseboard heaters in my 60-year-old home haven't leaked yet...so I'm not so concerned about that issue. Maybe the modern under-floor systems are prone to leakage, but the tech I have seems bullet-proof. If you need AC then forced air is your only hope...but we are cool with a well-shaded lot and a window unit or two.
  
  --
  Blar.
5. Re:It works well in cities. by Anonymous Coward · 2009-12-01 10:19 · Score: 0
  
  Most residential buildings in Finland are heated by piping hot water through radiators (often located under windows, which helps air circulate in the room). The water isn't boiling hot (you can grab the radiators with bare hands even if its thermostat is wide open), nor it is under high pressure (about same pressure and temperature as what you get from a faucet). Buildings in cities and towns get the hot water from the municipal water mains (heated by cogeneration power plants). Buildings in the boonies have a furnace or a heat pump in the basement that heats the water.
  Steam bombs my ass - I swear there's FUD against everything imaginable.
6. Re:It works well in cities. by puhuri · 2009-12-01 22:56 · Score: 1
  
  It is hard to see how maximum 35 degree C water (with 1 bar pressure) could be steam bomb. That is the water temperature I have running inside floors. Even if water coming into heat exchanger may some times exceed 100 C, and you can get seriously injured if you are close to pipe break, I prefer it much to system having flame and exploding gas.
  Most of time the heat is by-product of electric power plant, so distributed heating is a good way to improve overall efficiency.
7. Re:It works well in cities. by AigariusDebian · 2009-12-05 03:11 · Score: 1
  
  Most heating systems never reach the boiling point. The working temperature is between 60C and 90C. Noone wants to deal with steam.
Valium and Xanax for Engineers and Physicists by NoYob · 2009-12-01 07:25 · Score: 5, Funny
The pump is also very efficient -- you get five times the amount of energy you put in, he said.

So, engineers and physicists, when you see statements like that, how do you cope:
1. Stiff drink(s)
2. Xanax(s)
3. Dust off plans for your perpetual motion machine company to go public
4. Cry yourselves to sleep.
5. Other
--
It's NOT me! It's the meds! I'm on 1000mg of Fukitol.
1. Re:Valium and Xanax for Engineers and Physicists by maxume · 2009-12-01 07:37 · Score: 1
  
  It doesn't bother me much, lots of problems from school involved modeling the environment as a magic line.
  
  --
  Nerd rage is the funniest rage.
2. Re:Valium and Xanax for Engineers and Physicists by rockNme2349 · 2009-12-01 07:41 · Score: 2, Funny
  
  6. Post condescending comments on a forum that no one will read.
  
  --
  Sewage Treatment Facilities - "Our duty is clear."
3. Re:Valium and Xanax for Engineers and Physicists by JessGras · 2009-12-01 07:42 · Score: 5, Informative
  
  Heat pumps can be this efficient when you consider the claim is they can move five times as much (heat) energy as they consume (in electicity or other organized source). They are not claiming to generate more than they consume: only pump more than they consume - though vague and sensationalist phrasing in the journalism makes this unclear in the OP.
4. Re:Valium and Xanax for Engineers and Physicists by wealthychef · 2009-12-01 07:43 · Score: 1
  
  when you see statements like that, how do you cope
  Well, you could just try to understand from context, that they mean, five times the energy put into the system besides the energy recovered from the waste heat, which is "free" in this context.
  
  --
  Currently hooked on AMP
5. Re:Valium and Xanax for Engineers and Physicists by fred+fleenblat · 2009-12-01 07:45 · Score: 1
  
  you could assume he might be talking about coefficient of performance but he doesn't remember the exact right phrase.
  more troubling, even if he used the correct phrase, his intended audience probably wouldn't understand him.
6. Re:Valium and Xanax for Engineers and Physicists by Anonymous Coward · 2009-12-01 07:47 · Score: 0
  
  Didn't bother me much either, given that it was clear that we were talking about a heat pump, which one would hope moves more heat energy than energy it uses to perform its work, and which the thermodynamic laws only care about making sure you can't get more energy from running it in reverse than you did in moving the heat in the first place.
7. Re:Valium and Xanax for Engineers and Physicists by kryptKnight · 2009-12-01 08:03 · Score: 1
  
  You might want to go read about heat pumps. What the article describes is perfectly possible, using heat pumps for heating and cooling is very common in temperate climates.
  
  --
  Facts do not cease to exist because they are ignored. -Aldous Huxley
8. Re:Valium and Xanax for Engineers and Physicists by david.given · 2009-12-01 08:08 · Score: 1
  
  So, engineers and physicists, when you see statements like that, how do you cope:
  Easily, because I know that a heat pump is a machine that allows me to move 5X amount of heat from one location to another while only using X amount of energy to do it.
  (BTW, if you heat your house using electrical resistive heating, and you have a garden... go look up 'ground source heat pumps' from that article and save yourself lots of money.)
9. Re:Valium and Xanax for Engineers and Physicists by danlip · 2009-12-01 08:52 · Score: 1
  
  Heat is not energy*, at least not useful energy. Specifically heat alone is not useful for doing work. You need a heat gradient to do work. Heat pumps increase the heat gradient, and that gradient could be used to do work, but the amount of energy you would get out of that is always less than you put in.
  Heat pumps are a rather efficient way to heat your house, within a certain temperature range it can be much more efficient than burning chemical fuels.
  *(yeah, heat really is energy, but heat pumps just move it around, they don't create it)
10. Re:Valium and Xanax for Engineers and Physicists by deprecated · 2009-12-01 10:03 · Score: 1
  
  6. Drink the tears of Cowboy Neal. Fixed that for ya.
11. Re:Valium and Xanax for Engineers and Physicists by Upphew · 2009-12-02 02:28 · Score: 1
  
  Heat is not energy*, at least not useful energy.
  FU! Welcome to Finland. I'll let you wait outside, while you reconsider how useful heat is...
Re:German comma by macbuzz01 · 2009-12-01 07:28 · Score: 0, Offtopic

Dude, you gotta be careful, you almost Godwined.
Data center cooling in the winter by Anonymous Coward · 2009-12-01 07:28 · Score: 0

I know, this is off topic but...
I never understood why datacenters never had direct outside ventilation. In the winter, this could cut down on cooling costs and could benefit the building as well for heat. Depending on the incoming and exhaust temperatures, you could either redirect the exhaust outside or into the building. Lack of humidity control would be concern but is that the only reason this is not used more often?
1. Re:Data center cooling in the winter by afidel · 2009-12-01 07:40 · Score: 2, Informative
  
  That's correct, in many climates you would spend more energy trying to maintain humidity then you would save by not running the AC system. For larger systems many have a "freecool" option which runs the waste stream through the heat exchanger without running the compressors thus saving ~80% of the energy.
  
  --
  There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
2. Re:Data center cooling in the winter by djrok212 · 2009-12-01 08:01 · Score: 2, Informative
  
  This already exists, and is in use in many data centers, they are called Air Side Economizers, http://www.42u.com/cooling/air-side-economizers.htm
Quantum Dots.... by jameskojiro · 2009-12-01 07:30 · Score: 1

This is what is used to power Matroska brains.....

--
Tsukasa: All I really want, is to be left alone...
Re:The problem with approaching Carnot efficiency. by wealthychef · 2009-12-01 07:41 · Score: 1

the process will take longer and longer time
Well, but in a flow reactor, that won't matter. It might take an ounce of water a long time to go through whatever this system is, but once it's flowing, it does not matter how much time it takes. Flow in == flow out, presumably. It will seem instantaneous after the startup time.

--
Currently hooked on AMP
That's good by Yvan256 · 2009-12-01 07:41 · Score: 5, Funny

"Honey, why are you watching so many porn streams at once?"
"Because I'm cold!"
It IS great by dgr73 · 2009-12-01 07:44 · Score: 3, Informative

Not to mention that when you have hot water coming out of the pipes, you don't need a water boiler, which is something all houses without kaukolämpö (remote heat) need. All in all, the infrastructure is in place in many places in Finland, with insulated pipes dug deep enough into the ground to keep the heat, so why not take advantage of it.
Obligatory by interiot · 2009-12-01 07:46 · Score: 2, Funny

"The Internet is not a big truck. It's a series of tubes. And if you don't understand, those tubes can be filled and if they are filled, when you put your message in, it generates more heat and it's going to be delayed by anyone that puts into that tube enormous amounts of boiling water, enormous amounts of boiling water."
It's a fucking heat pump, people. by R2.0 · 2009-12-01 07:48 · Score: 1

It uses cold water from a central plant and then it gets cooled back down by a chiller/heat pump. The condenser water off the heat pump is then used to heat homes. Basically, the plant is rejecting it's heat into the local housing system.
The part about thermoelectric devices is a total non-sequiter.

--
"As God is my witness, I thought turkeys could fly." A. Carlson
Central Heating to the extreme by OzPeter · 2009-12-01 07:53 · Score: 1

I experienced this to some extent when working in Magnetogorsk, Siberia in '94. The hot water for a lot/all of the town was supplied centrally and piped all over the place in 1m diameter pipes (above ground).
Aside from the efficiency issues due to heat loss from the pipes, the main fun factor in this system was that the distribution was not terribly fine grained. As a result the authorities shut down the hot water for entire sections of the city when they wanted to do extended maintenance - and by that I mean up to a month at a time.
Its amazing how short a time it takes to get enough hot water for a bath when you are heating it up one saucepan at a time on a stove!
Hopefully the people who will be reliant on the excess data centre heat won't have the same dependency problems. Its much easier to hook up a spare electrical system than it is to re-pipe hot water

--
I am Slashdot. Are you Slashdot as well?
1. Re:Central Heating to the extreme by Anonymous Coward · 2009-12-01 08:04 · Score: 0
  
  Magnetogorsk design sounds like good old Stalin-age design; industrialisation and solution of some kind was OK even with huge inefficiencies when the empire had practically free energy to burn to cover defects of over-the-top large scale design. And well, inhabitants probably rather hard some heating outages than froze to death in middle of Siberia... Helsinki doesn't do it quite that way. :)
2. Re:Central Heating to the extreme by badran · 2009-12-01 08:30 · Score: 0
  
  You should have bought a pair of buckets... This is what the locals do ;)...
3. Re:Central Heating to the extreme by Anonymous Coward · 2009-12-01 08:41 · Score: 0
  
  Helsinki is in Finland, not in Soviet Russia 15 years ago. Almost whole city is heated by district heating system.
  http://en.wikipedia.org/wiki/District_heating#Finland
4. Re:Central Heating to the extreme by Anonymous Coward · 2009-12-01 11:59 · Score: 0
  
  The system in Helsinki is considerably more fine grained thankfully. Quickly looking at wikipedia, it says the availability is a whopping 99.98%, I would assume for the duration of the remaining 0.02%, the water in the system will retain enough heat not to affect much. The Helsinki network is also huge, so there is plenty of redundancy. Basically the entire metropolitan area is hooked up, fed by the excess energy of four coal plants, as well as perhaps 15 heat only plants that are fired up in the winter.
Forced air is too dry by mi · 2009-12-01 08:05 · Score: 3, Informative

Well, they have to be, because you're basically threading a steam bomb throughout your entire house. I'll stick with forced air thank you.
Forced air will dry you into a raisin. It is December — do you notice, how dry your lips are in the morning?
You need humidifiers to fight that effect... No, hot water — pumped through fixtures made of cast iron, or something, that's even slower to warm up and cool down — is the best heating solution... It could be expensive, but it is the most comfortable of what's commonly available today.
The oft-used copper and/or aluminum fixtures are bad, because the temperature will be fluctuating widely between the times, the heat is turned on by your thermostat and the times, when it is off. Our bodies are more sensitive to changes in temperatures, than to the temperatures themselves. Also, a quickly-heating material ends up losing heat mostly through convection (heating up air, that rises to the ceiling), than through radiation, which warms you directly (via infra-red).
Stainless steel is better in that regard than copper/aluminum, but not as good as cast iron, heavy and "unattractive" as those things might be...

--
In Soviet Washington the swamp drains you.
1. Re:Forced air is too dry by undercanopy · 2009-12-01 08:19 · Score: 1
  
  Let me help you with that post
  
  Seriously, though informative, it was painful to read.
  
  --
  -- D-23994, Muff#2613
2. Re:Forced air is too dry by fedos · 2009-12-01 08:25 · Score: 1
  
  Stainless steel is better in that regard than copper/aluminum, but not as good as cast iron, heavy and "unattractive" as those things might be...
  I happen to love the look of cast iron. I recently had trouble buying a cast iron dutch oven because most of those available in retail are coated in enamel. Although this is popular, I prefer the rustic look of the cast iron.
3. Re:Forced air is too dry by lewiscr · 2009-12-01 09:22 · Score: 1
  
  Buy from a camping/outdoor store. They usually have the non-enameled versions, for a lot less. Or search Amazon, and take advantage of super-saver shipping on a 15 pound item. :-)
4. Re:Forced air is too dry by scottv67 · 2009-12-01 16:17 · Score: 1
  
  >Forced air will dry you into a raisin. It is December — do you notice, how dry your lips are in the morning?
  
  I'm sorry but I'm going to have to call bullshit on your comment. You implied that running hot water through cast iron radiators will result in a comfortable house but using a forced air system (let's say it uses natural gas) dries out your lips. Please provide some details, math and/or science to back up your claim. If you use hot water to heat the house to 70 degrees, how can the relative humidity in the house be any different than when you heat the house to 70 using a forced air furnace (assume the furnace is a high efficiency model that has its own air intake and exhaust pipes).
  
  I don't see how using those two different heating methods can result in different relative humidity levels at the same indoor temperature.
5. Re:Forced air is too dry by mi · 2009-12-02 02:20 · Score: 1
  
  Please provide some details, math and/or science to back up your claim.
  Simple... You'll be moving air. And by doing so you'll be subject to the same effects, as the clothes drying in the wind. You want to be warmed up through infra-red radiation as much as possible, with the minimum convection component, because convection moves air (hot rises up).
  It also makes for uncomfortable differences in temperature between floor and ceiling — you may feel chill in your legs (or your toddler may be cold), but you'll breath noticeably hotter air.
  And, finally, you feel hot when your furnace starts, and when the heat turns off (upon reaching the specified temperature), the temperature begins to drop fast. You want something with high inertia, because our bodies detect temperature changes and begin feeling "hot" or "cold", when the actual temperature may still be perfectly fine.
  Forced air is very economical to install, because nothing ever leaks nor rusts and the same pathways used for cooling in summer can be used for heating in winter. And with integrated humidifier(s) and ceiling fans (to push hot air back down) it can be Ok. But if "money is no object", you want hot water (running at the lowest possible temperature — not steam!) running through either cast iron fixtures, or — even more expensive — the little pipes in your floor.
  
  --
  In Soviet Washington the swamp drains you.
6. Re:Forced air is too dry by LWATCDR · 2009-12-04 08:49 · Score: 1
  
  "Forced air will dry you into a raisin. It is December — do you notice, how dry your lips are in the morning? "
  Nope but then I live in Florida.
  
  --
  See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
7. Re:Forced air is too dry by AigariusDebian · 2009-12-05 03:14 · Score: 1
  
  Well, most of the 'hot' or 'cold' feeling actually comes from your feet. So it does not matter much what you breathe in (within a few degrees) as long as your feet are warm. That is why floor heating systems are the most economical, because you can comfortably maintain much lower temperatures.
Space Heater by jgtg32a · 2009-12-01 08:05 · Score: 1

See my sig; My computer also functions as a nice little space heater, if I leave the door to the study closed it will become the warmest room in the house.
1. Re:Space Heater by FatSean · 2009-12-01 09:11 · Score: 1
  
  Yeah, I point the case fans at my feet in the winter time!
  
  --
  Blar.
2. Re:Space Heater by smoker2 · 2009-12-01 11:21 · Score: 2, Funny
  
  I have a power brick under each foot. Toasty !
What about the exec office? by filesiteguy · 2009-12-01 08:09 · Score: 2, Funny

Now that we have the issue with the heat coming from the server room solved, let's tackle the hot air coming from the executive offices next.

Any ideas?

--
The Kai's Semi-Updated Website Thingy
1. Re:What about the exec office? by sjames · 2009-12-01 09:55 · Score: 1
  
  It's been tried many times, but no matter what you do to it, you just can't get the bullshit smell filtered out.
2. Re:What about the exec office? by smoker2 · 2009-12-01 11:23 · Score: 1
  
  Fill their o[ro]ffices with water ?
3. Re:What about the exec office? by rdnetto · 2009-12-01 20:28 · Score: 1
  
  Have you tried using corks?
  
  --
  Most human behaviour can be explained in terms of identity.
4. Re:What about the exec office? by filesiteguy · 2009-12-02 00:40 · Score: 1
  
  ROTFL!
  
  --
  The Kai's Semi-Updated Website Thingy
Re:The problem with approaching Carnot efficiency. by pla · 2009-12-01 09:19 · Score: 1

Carnot efficiency is defined by the efficiency of a reversible heat engine operating between the given temperatures;

"Heat engine" != direct thermoelectric conversion (whether via quantum dots or just plain ol' Peltier junctions).

The Carnot limit simply doesn't apply to direct conversion, and AFAIK, no theoretical limit to near-100% efficiency (minus entropy) exists for the latter.
Quantum Dot by physburn · 2009-12-01 09:36 · Score: 1

Looking forward the Quantum Dot heat engine, it nothing to do with the Helskini project and deserves a thread of its own. The authors claim up to 90% Carnot efficency is possible. Even at 40% this is better than almost every heat to electricity generator mankind has made so far. It would replace turbines and generators everywhere (if they can run that hot), and doubling the efficiency of gas/coal/oil and nuclear power stations. That's fantastic, and probably decades aways.
---
Heat Recovery Feed @ Feed Distiller
It's much much much more efficient by Colin+Smith · 2009-12-01 10:33 · Score: 1

Is pumping boiling water through pipes the most efficient way to heat houses?
Yes. Easily. The pipes in district heating systems are heavily insulated, and large.
http://www.exakm.gr/images/Transmission%20pipe%20installation.jpg
1. It's WAY better than burning fuel to create electricity to transmit to the houses to create heat.
2. It's substantially better than pumping gas out to millions of tiny water boilers which do nothing but heat water.
3. it's "waste". The bit most power companies throw away after generating electricity. Anything you get from it is essentially "free".
You can turn a 35% efficient power station into an 88% efficient one by making use of waste heat in this manner.
http://www.helen.fi/energy/yhteistuotanto.html

--
Deleted
Heat Recovery Ventilation by Doc+Ruby · 2009-12-01 10:48 · Score: 2, Interesting

Common commercial devices for homes already use heat exchangers to recover 66% or more of heat from vented air, heating the incoming fresh air with it. During heating seasons, machinery's inefficiency generating heat can replace heat that would have consumed more energy. Bathroom fan vents cost under $300.
What we need is good heat storage devices. If a lot of heat can be stored during the cooling season, and released during the heating season, these electrical devices become close to 100% efficient. Places like Helsinki have much longer heating than cooling seasons, so they're good places for datacenters that can recover heat for use.
The problem is that water is about the densest heat storage material we have, but it doesn't store very much. And even the most cutting edge insulators, aerogels, are only about 2x as insulating as the current common top performers, closed cell foams, and only about 4x as insulating as the earlier common stuff like fiberglass and cellulose. If we could store in similar volume the energy that fuels like oil store in chemical covalent bonds instead in physical materials like high specific heat fluids that don't get that hot, we'd have a lot more options in engineering efficiency. If we could regenerate chemical fuel from heat at very high cycle efficiency, we'd have something of a miracle cure for many of the worst of our industrial ills.

--
--
make install -not war
Re:The problem with approaching Carnot efficiency. by Rising+Ape · 2009-12-01 11:07 · Score: 1

The Carnot limit applies to any heat engine, no matter how it works. Heat -> work means no efficiency higher than Carnot, sorry. Your "minus entropy" part gives that away really, as that's what's responsible for the Carnot limit in any case. Entropy change of X = heat transferred into X / temperature of X. So taking heat out of something causes an entropy decrease, hence the need for a cold sink to create an entropy increase so the overall entropy change is positive.
Telehouse West, London by Anonymice · 2009-12-01 12:13 · Score: 1

...the new £80m extension to Telehouse Europe in the Docklands, is also being built with a similar idea in mind & is scheduled to begin operations during the first quarter of 2010.

The partnership will see Telehouse West save up to 1,110 tonnes of CO2 emissions per annum and provide up to nine megawatts of power for the local neighbourhood. The energy savings will equate to boiling 3,000 kettles continuously. The disposal of waste heat from cooling systems is one of the most significant sustainability issues associated with data storage. This will be the first time a heat export strategy has been introduced in the UK for this type of data centre facility.
In fact, I seem to recall a discussion about this on here a couple of months ago about yet another project doing the same thing. The consensus was that whilst there was a lot of air pumped out, it wasn't exactly hot & it wasn't useful for much more than good PR for the host - far better efficiencies could have been made, spending the money elsewhere. (This statement brought to you by Slashdot whispers of an oriental nature.)
Industrial Water Treatment by Anonymous Coward · 2009-12-01 17:22 · Score: 0

I tend to think that some of the problem they will see with trying this is scale build up on the pipes as well as corrosion of the pipes unless they are doing something for the water treatment end of itself. I am by no means an expert but green technology has been around for over 100 years when dealing with cooling and heating and water ( http://www.g-c.com/ )