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Keeping Computers (And People) Warm In Winter?

Grimwiz writes "Similar to a few of you, I have some of my computers on a UPS. However, the UK press have recently been warning that power supply interruptions are likely this winter and I've been pondering about upgrading my power protection from those few machines to include a few key house components. In particular, I need to ensure that the gas-powered (but electrically controlled) central heating stays working. I have reviewed a few solutions, including Solar / Photovoltaic or purchasing a generator but they seem to be hugely more expensive than my simple UPS solution, although they do provide a much longer lasting solution than running off batteries. (A battery solution becomes quite expensive if I require more than an hours backup.) My power requirements for a quiescent house is about 4amps @ 250V, and I'd like to survive at least 8 hours. What solutions do you recommend?"

49 of 568 comments (clear)

  1. Deep cycle marine battery by erick99 · · Score: 1, Informative

    You should be able to get 32amp/hours with deep cycle batteries. You could use an array of series/parallel to get to your 250volt requirement. They could be on a constant trickle charge to keep them topped off. This is not the least expensive solution I am sure. Storing those things can be kinda of tricky though. Oh, well, just an idea.

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    1. Re:Deep cycle marine battery by theparanoidcynic · · Score: 5, Informative

      Who modded this informative? 250 volts DC is not the same thing as UK line power. (250 Volts-rms @ 50Hz.) This idea is as dangerous as it is useless.

      What you need is an inverter. The cheap ones that you can get anywhere would work fine for your computers, but for your furnace you'd need an inverter of the caliber used in off-grid homes. (Probably more than you want to spend.)

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    2. Re:Deep cycle marine battery by bergeron76 · · Score: 1, Informative

      Who modded this as informative? Using an Inverter is a HIGHLY inefficient power source!

      The parent should use a higher efficiency well-coupled power supply and power draw device(s).

      --
      Don't think that a small group of dedicated individuals can't change the world. It's the only thing that ever has.
    3. Re:Deep cycle marine battery by theparanoidcynic · · Score: 2, Informative

      Um, modern inverters have real-world efficiencies of %90+. By any standard that's marvelous.

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    4. Re:Deep cycle marine battery by bluGill · · Score: 2, Informative

      Maybe. His computer doesn't run on AC at all. You can buy 12 volt power supplies for some computers. Telecom runs their computers on 48 volts DC. (not all, but all the important ones)

      Light bulbs don't care about DC. Small motors don't care. I suspect that he only has two devices that care: his fridge, and his furnace. Everything else transforms either doesn't care, or transforms the AC into something else anyway, so a good hacker could find that something else and make it work.

      Warning, if you consider the above, don't just try things. You never know when you will discover the rare device that does care. Do some research first. The principals apply though.

    5. Re:Deep cycle marine battery by ColaMan · · Score: 4, Informative

      For all the posters in this thread :

      DO NOT USE HIGH VOLTAGE DC IN YOUR HOUSE.

      Apart from the obvious issue with appliances, there's another reason.

      Mains 240V AC switches are not rated for that kind of DC voltage - the arc from switching DC at those voltages will most likely destroy the switch. This arc is only brief with AC at 50/60 Hz as the arc will extinguish when the voltage drops to zero every half-cycle.

      This is why switches are normally rated along the lines of "240VAC/32VDC"

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    6. Re:Deep cycle marine battery by EvilMidnightBomber · · Score: 2, Informative

      Actually, all switching power supplies take the input line voltage and rectify them to DC anyway. It is perfectly acceptable to feed them DC straight off. The DC potential needed would be equivalent to the peak-to-peak of the minimum recommended AC operating voltage of the unit. For 120vac, 60Hz, this would be 120*sqrt(2)=170v.

  2. UPS + Generator by Anonymous Coward · · Score: 5, Informative

    Use a normal UPS to bridge the first few minutes in which you can comfortable start a generator.

  3. More batteries by Foxxz · · Score: 3, Informative

    21x twelve voltage batteries rated at 30Ah hooked up in series :)

    -Foxxz

    1. Re:More batteries by erick99 · · Score: 2, Informative

      That would only be one hour, he wants eight. 21 x 12 = 250volts at 30 amps, he would then need this times eight to get to his eight hour requirement. There are much larger capacity batteries that would get the battery count down, though.

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  4. How cold does it get in the UK during winter? by TykeClone · · Score: 3, Informative
    If it doesn't get too cold, then the house should be able to survive 8 hours without the furnace running. Pipes are the only things to be really concerned with - just crack the taps to leave a trickle of water running so that they don't freeze and you're good to go.

    Oh, and drink whiskey. Lots and lots of whiskey. It makes good antifreeze for the blood :)

    --
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    1. Re:How cold does it get in the UK during winter? by Lumpy · · Score: 5, Informative

      your tips are right except for the joke about the liquor. getting drunk will increase your chances of death in extreme temperature.

      It does suprise me the number of people in civilized lands that are completely clueless to human survival.

      If the house get's to 1 deg C your pipes are still very safe 0.5degC is where I would start to worry. about the pipes. Being used to winters regularly getting to -5 to -10degC and recieving at least 36-48 inches of snow by mid winter I usually get a good laugh from those that live in warmer climates and their lack of knowlege about life.

      I would add to your tips. dress in lots of layers. a couple of undershirts with a regular shirt, a sweater and then a baggy sweatshirt, 2 pairs of pants on and then a regular jacket coupled with gloves and decent boots (3 pairs of socks, 1 plastic bag over each foot (if you venture outside) then in medicore boots can survive quite a long time in -3deg C weather out of the wind and elements. a Hat is a MUST if you venture out in any wind.

      your computer can get down to -30 degC before possible dsamage, and then it's highly unlikely. This is negated by the silly people with water cooling and not using ethelyne glycol for freeze, heat protection.

      layers are important, buy some long underwear or sweatpants just in case. In fact a pair of regular underwear, long underwear, and two pairs of jeans will easily protect a walking person in arctic temperatures if DRY for days.

      finally, gloves. get some that are decent and good socks/boots. you can survive horrible temperatures while your nose., fingers and toes freeze solid and then fall off days later.

      finally if it getr's really horrid, pitch a tent in your front room (a 4 season tent) and sleep in there. containing your heat in a smaller space will protect you massively in extreme temperatures.

      but the best thing is to find a female that is unprepared and scared and convince her that she and her 2 friends must sleep naked together in that tent with you in order to survive...

      you know use that shared body heat angle.. Chicks love the prepared rescue type... oh and don't shave for a day or so to look rugged... they dig that too...

      --
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    2. Re:How cold does it get in the UK during winter? by Easy2RememberNick · · Score: 2, Informative

      I wouldn't wait until it got that cold to start worrying about my pipes.
      Newer homes have plastic piping instead of copper. I'd say copper would freeze quicker since it is a better conductor than plastic. Also, pipes could be in uninsulated or not very well insulated parts of a home such as the basement where cold air will pool first.
      I'd rather be safe than sorry and take action as soon as possible, turn the taps on at about 5C; the hot and cold.

  5. its AC! by Dr.Knackerator · · Score: 5, Informative

    so sticking batteries in series to 250v is not going to be a good move.

    stick em in parrallel and hook up a 240V inverter.

    32ah is a bit on the weedy side, around 110ah is standard and easy to find. over in the uk they tend to be called leisure batteries. dont use normal car batteries they are not designed to be run down - you will damage them

  6. Gas - Electricity by Gulthek · · Score: 5, Informative

    If you have gas then you can get a natural gas electrical generator. Connected to the gas line, when power goes out some models will automatically ignite and provide power to the house, some require a manual ignition.

  7. Cut the Fat by Nehi+the+Ganchark · · Score: 5, Informative

    Another approach you could take is to take steps to make your household more energy efficient -- upgrade your insulation, get energy star rated appliances, change to flourescents -- all of those things we should have learned in school and keep learning about in the adverts that come with our energy bills.

    You could look into alternative energy sources, but since cost is a factor, I won't go into details, except to say the up-front costs can be prohibitive.

    In all honesty, a generator IS your best option if you want to keep running in a blackout. You may be able to poke around and find a used one for 1/3 the cost of the new article.

    If that's still not an option, build a fire pit and stock up on wood...

  8. This is the UK we're talking about. by reality-bytes · · Score: 2, Informative

    The majority of houses in the UK do not have cellars. The majority of those that did pre-1939 have since been bombed flat.

    As for the second component of your comment, isn't that stating the obvious?

    Personally I'd go for photovoltaic supply as I've nearly succeeded in getting a Mini-ITX based server operating 24/7 on solar power via a bank of 6v FLT batteries.

    For heating, being as we face no natural-gas outages just now, I'd recommend by-productive heating from your cooking sources after their normal use. The laws of thermodynamics can be useful when heating a house by this method ;)

    --
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  9. Re:Need a generator? by stratjakt · · Score: 5, Informative

    Better yet, one of the hybrid gas/electrics, those things basically have what amounts to a mega-super-duper alternator, and you can plug right into the vehicles.

    I just got back from Epcot, where GM had a display about their gas/electric hybrid pickups and how they were used during the Florida hurricane's as mobile power generation stations. Apparently you can plug right into one of them, and they'll give you 120 VAC @20 amps, which is not too shabby. (No doubt the UK model serves up 240VAC)

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  10. Re:I suggest... by Anonymous Coward · · Score: 5, Informative
    The other thing you need to consider when designing your system: what power factor will you be dealing with?

    You see, most UPS systems are rated in "volt amps". If you have a purely resistive load, that's the power drawn. However, as soon as you throw any inductors or capacitors into the circuit, the equation no longer holds. This is where the power factor comes into the equation.

    You're talking about 4 amps at 250 V, over a period of 8 hours. That's 1000 watts for eight hours, or 8 kilowatt hours. However, this doesn't cater for the power factor -- if your house has a power factor of 0.8, for example, batteries capable of providing that current for that period of time will run your house for about six and a half hours. So you'll need to bring up the batteries to 10 kilowatt hours to compensate -- either that, or (if it's an inductive load) buy a whopping great big bank of capacitors to bring the power factor back up to a reasonable level.

    Industrial sites have to deal with this; the power company doesn't like sites that draw excessive current compared with their power usage, and will bill them big time if their power factor is too low. Most residential sites aren't a concern in this regard; their usage is too low for the power company to worry.

    If you've specced it out based upon the current draw (ie: sticking a current meter in series with the circuit), you've automatically compensated for the power factor. If you've done the maths based upon the power rating of the devices, though, you need to consider this stuff. Any competent electrician should be able to help you out here.

  11. Re:Car batteries by Alien54 · · Score: 4, Informative

    See also this detailed article on what kinds of batteries might do the job. good practicle info.

    --
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  12. Re:Our gas supply by Somegeek · · Score: 2, Informative

    You can get gas detectors (like a smoke detector but about $50) that will warn you of a gas leak. I have one in case I have a problem with the propane in my house. You might want to look into that as a backup. Death is supposed to suck.

    --
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  13. AC, DC, and voltages by Frank+T.+Lofaro+Jr. · · Score: 4, Informative

    Agreed about AC and DC, but here is one thing to keep in mind.

    If you run an incandesent bulb off DC it will work just fine, and probably last a VERY long time compared to how long it "should" last.

    I thought the UK ran at 240 volts, not 250. I thought South Africa was the only country that ran 250. I though most of Europe was 220 and Europe and the UK were going to unify their standards at 230. Anyone care to comment? BTW, Japan runs at 100 (the lowest, 250 is the highest) and I think Trinidad runs 110 (the USA does NOT, see below).

    Of course the USA used to be 110 volts, but is now 120 volts, but so many Americans still don't know that. It actually causes problems with old tube radios.

    --
    Just because it CAN be done, doesn't mean it should!
    1. Re:AC, DC, and voltages by Kiryat+Malachi · · Score: 2, Informative

      The line voltage isn't usually standardized to a particular voltage, rather to a range; for instance, in the US anything between 107 and 127V is considered "acceptable".

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    2. Re:AC, DC, and voltages by Anonymous Coward · · Score: 1, Informative
      Part of your confusion is how to measure AC and what kind of waveform it has. Peak to peak, the AC is more than 250v or whatever. The standard is RMS (root-mean-square), but that involves some calculations. Many old voltmeters measured average voltage, even when they claimed RMS.

      You are confused about the USA's standard voltages. You will see it referred to as 110VAC or 120VAC. Some compromise it as 115VAC. RMS is 117.something, but only a perfectionist says that. Ditto for 220VAC and 440VAC standards.

      Another factor is that the voltage fluctuates. When power generation is matched with the load, things are OK. Then, at 6:00AM, everbody wakes up and starts using electricity at once. Things can sag. When everyone leaves for work, generation can exceed demand and things go up a little. Electric motors are great spikes generators.

      Sidenote: The power coming into US homes is 220VAC (240VAC or whatever.) It is center tapped to get two 110VAC circuits. (US outlets have a neutral terminal and a hot terminal.) If your ground (earth for you British types) is bad, you can get a 80VAC circuit and a 140VAC circuit (or something like that.) Then half of your lights are dim and the other half burn out.

      Many inverters generate a "modified sine wave," which is a marketing term name for a "modified square wave." (A true sine wave is expensive and/or inefficient.) Be careful about using them with computer equipment, especially laser printers.

      On the plus side, improvements in power supply technology means many consumer electronics will accept a wide range of voltages. (Look on the back of your computer monitor.)

    3. Re:AC, DC, and voltages by lga · · Score: 2, Informative

      Officially the UK now runs at 230 volts to be harmonised with Europe. Half the time, however, it hasn't changed from the 240 volts we have been using for the last 60 years (Before that it was 250 volts)

      Across Europe the official standard now is 230 volts -6% +10%

      This range therefore includes the whole range of all European countries including 220 volts, 230 volts and 240 volts. The standards are deliberately slack so that we can all say we have harmonised voltages but actually keep our original one. How stupid are these politicians???

  14. Power and heating solutions by mhollis · · Score: 4, Informative

    You live in the UK, which tends to not have enough sun to make photovoltaic worthwhile. Either you need a positively huge array (and the one in the picture on the website you link to looks like it fairly covers all available space on the roof) or you need lots of sun and Britain just doesn't have that.

    Your best (but polluting) source of electricity is a honda generator. You can buy them all over and I'd imagine a DIY outlet will have a few models to choose from. One member here mentions that he did quite well after a hurricane with one. Do not ever run one indoors. They create carbon monoxide so their exhaust needs to be away from the house so that it cannot seep in through a window, vent or other entrance.

    You will need a UPS with a generator if you are running a computer, but you don't need one for equipment that may be shut off and restarted, like fans, washers, dryers, refrigerators, etc. You need enough battery life to be able to survive a power outage until you can get the generator running. So if your computer needs to run all of the time, make sure your battery will last long enough for you to wake up, put on clothes and go tend to the generator.

    Insulation and sealing are the best non-polluting way to increase heat -- and you will save money on heating fuel all winter, so it pays for itself.

    The more insulation you have in your walls and on the roof, the better you are. Be sure there is an air pocket that runs up your eaves on your roof so that you don't get mold on your rafters and shingles and you're all set. You want to add to your "R-Value" in such a way so that you can keep enough home heat inside to keep warm in any full-day power outage.

    The homes I've visited in England have tended to be fairly drafty as compared to US homes. So look at your doors and windows and make sure they seal well when you close them. Windows ought to be double-pane windows, which hold in heat four times better than single-pane.

    I don't necessarily recommend that you keep up the electricity lifestyle during a power outage. Turn off your computer, unless you need it for work. Use hurricane lanterns and "Coleman" white gas lanters with mantles to light up your home (they'll also add heat but not as efficiently, perhaps, as a real heater). Run up your heater on your generator until it is quite warm inside and then shut it off until things cool down just under bearable temperatures. Don't open any windows to moderate the heat and keep things sealed up as best you can. Don't use the television, save to get information about the power emergency (a radio is usually better anyway for up-to-the-moment information anyway). Run your generator sparingly.

    And talk to your local MP and ask why your area is so ill-served with electricity. Ask if his district is not one of second-class citizenry if your power goes out as often as is predicted. Gather your friends and neighbors to help him think more clearly (if he sees you as a voting bloc, he'll think clearly) about the need to introduce a change in the system.

    --
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  15. Get a thermopile and Millivolt gas valve by deeptrace · · Score: 5, Informative

    You can run a gas furnace off of the heat generated from the pilot light using a thermopile and a millivolt controller gas valve. I have heated my house this way in the middle of winter over a 3 day ice storm blackout.

    It must be a hot water system. Just open all of the zone valves and eventually the whole system will heat up to the furnace temperature via convection in the pipes. The furnace will cycle between its low and high temperature, even with no power except the thermopile.

    This is a standard type of system in the US. Not sure about the UK.

    See http://hearth.com/what/gas/howgasworks.html for info on millivolt gas systems.

    1. Re:Get a thermopile and Millivolt gas valve by intellicharge · · Score: 2, Informative
      Actually, you don't even need to change your gas valve. Find out the control voltage for your gas valve (its printed on the valve - likely 24 volts), and then build yourself a small battery back to make roughly the same voltage. A few 9-volt batteries should do.

      When the power's off and you want heat, open up your furnace, find the small transformer that powers your gas valve/ thermostat, disconnect the wires on the LOW VOLTAGE side and connect them to the battery pack.

      When the thermostat switches on, the gas valve will open (powered by the battery pack) and the furnace will start. Since gas valves in most furnaces generally draw very little current, even a few 9-volt batteries should be sufficient to keep it operating for a long time.

      Note however, that this ASSUMES your system is a hot water boiler setup. If you've got a forced-air system, you're going to need a UPS to power the blower!

  16. Re:furnace won't work with UPS, don't bother tryin by gl4ss · · Score: 2, Informative

    mod up.

    backup heating doesn't have to be the furnace... unless you got some very important stuff there in which case you should have a generator anyways.

    --
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  17. Watch the battery doesn't explode by shostiru · · Score: 4, Informative
    Seriously. We've done this at work (both satellite batteries and replacements), and had one go kaboom when H2 gas caught a spark. The top of the battery dented the ceiling, and we had to throw baking soda all over everything to neutralize the sulfuric acid. If anyone had been in the area at the time they wouldn't been in a world of hurt.

    A co-worker had seen the exact same thing happen in his last job.

    I'm not familiar with what "VRLA" means, but unless the battery is sealed gel-type and rated for deep discharge and repeated cycling, I'd wouldn't use it.

  18. Power supply interruptions are NOT likley! by kragwad · · Score: 5, Informative
    "However, the UK press have recently been warning that power supply interruptions are likely this winter "

    Get your facts right. I don't know what coverage you're reading (the tabloid papers I suspect) but there is no power supply crisis forcast for this winter.

    What has been commented on is our increasing reliance on imported power from the continent, and coupled with the decommissiong of several major nuclear power plants over the next decade if we don't act now there could be problems in the future. I don't think UPS'ing your heating system is necessary just yet :)

    "But the government said the outlook for power supplies this winter was good and accused the union of "scaremongering""

    Source: http://news.bbc.co.uk/1/hi/business/3751810.stm

  19. Re:Central heating for 8 hours? by PepperGrunties · · Score: 2, Informative

    One drawback to a generator is the amount of fuel that it will use. I bought one just before Frances (I live near where it made landfall), and it will consume 5 gallons in 12 hours at half power or 2600W. That really sucks when all of the gas stations are closed because they have no power or gas and you end up siphoning gas from the lawn mower, girlfriend's truck, etc. Does that happen with your typical winter storm?

    Also consider building a shelter for the generator - we lost some food because I couldn't run the generator until the rain stopped (12 freaking hours later...)

    If you decide to wire it directly to your breaker panel, do it right. There are transfer switches made for this application that will prevent killing linemen who aren't expecting the lines to be hot, as well as protecting all of your shit from catching on fire. Your insurance company will not pay for anything and you can also end up with some legal problems.

    The first thing I did with the generator? Made coffee of course.

  20. Here's a cheap and effective way to do it! by intellicharge · · Score: 3, Informative
    If you don't want to shell out the money for a commercially built generator, you can likely put together your own system for about $50.00 CDN using some scrap car parts and an old lawnmower.

    That's probably less than it would cost you to add a SINGLE additional battery to your system.

    Here's how: Find yourself an old "horizontal" style lawnmower engine (anything over 2HP will do) and a car alternator - the bigger the better. Put a pully on each, string a V-belt between them and bolt them down to a thick piece of plywood or better, some sort of metal frame. Using the wire from a set of old booster-cables, hook the output from the alternator (which should be outside, of course) through the nearest convenient window (or drill a hole in the wall) and across your UPS battery (making sure it is the CORRECT POLARITY). When the power goes out for more than 20 minutes, go outside and start up the engine for practically unlimited runtime.

    Even with a small car alternator, this rig will easily give you 12 volts at fifty amps. If you use a larger alternator, like the kind you would find on a truck, you can get 12 volts at up to a HUNDRED amps (= 1,200 watts).

    I once put a system like this together for fun for under $50.00 CDN, ($30.00 for a beat-up old engine in the local bargain-finder and $20.00 for an alternator from the local scrapyard.) This is significantly less expensive than buying even a single extra battery, which would cost about $80.00. The thing would run for HOURS before needing refueling, and if I wanted longer runtime I could have just added a bigger gas tank.

    Now, before you pack up your wrenches and head down to the local scrapyard, there is something you need to check: Does your UPS use a single large 12-volt battery, or does it use two smaller 12-volt batteries in SERIES for a total of 24-volts? If your system has two 12-volt batteries in series, you're going to need a 24-volt alternator. Where do you get a 24 volt alternator? Well, most Land Rover vehicles have 24-volt alternators, as would practically any kind of emergency vehicle, most military vehicles, and many large trucks. So, if you need a 24-volt alternator and can't find a Land Rover at your local wreckers, head to an INDUSTRIAL vehicle scrapyard.

    For the load you initially described, (250 volts @ 4 amps = 1,000 watts at continuous use) you would need a sustained power INPUT of about 1,200 watts. Note however, that in reality you will probably NOT need 1,000 watts continuous output as your furnace blower will be cycling on and off as will the other loads in your house. The UPS's battery will cover the extra load when everything IS running and recharge from the alternator when it ISN'T. This means you can likely get by with a smaller alternator.

    Overall, the solution I have described is ugly, noisy, and isn't likely to last through more than 100 hours of use. But it's also cheap, light (compared to a battery), easy to hook into the UPS, quite reliable, and works great if you only need a few hours of additional electrical power. If you're mechanically inclined, this is the cheapest and most effective solution I can think of.

    If you're really keen on the whole batteries/UPS/alternator modding-it-to-run-on-practically-any-source-of-pow er thing or just want even more reasons why trying to run it off solar power would be a terrible idea (at least where you live), I did a really interesting writeup on this for an anti-landmine technology competition a few years back. We made the whole reference design that we came up with effectively "open-source", so feel free to use it as you please. You can have a look at that here: http://www.intellicharge.ca/Downloads/Downloads.ht m The server has pretty serious bandwidth so it should be relatively /. resistant, but please don't rack up our hosting bill by downloading the full 1200dpi 114 MEG "print resolution" version unless you have good

  21. clarification by zogger · · Score: 3, Informative

    coleman gas lanterns or stoves or heaters that run on liquid coleman fuel or unleaded gasoline "white gas" are not recommended for indoor use. You'll kill yourself with CO buildup as they are sucking O2 out of the air. They will even tell you that on the box. The propane fired ones are a lot cleaner and safer to burn indoors, and even then you should have some windows cracked. You can get adapters for around 10$ that will let you attach them to a 20 lb refillable tank instead of the expensive 1lb throw aways they come with.

  22. Re:I suggest by Anonymous Coward · · Score: 1, Informative

    Home Depot (at least locally) sells natural gas powered generators that can replace your
    utility feed in the case of a blackout. As I
    recall, these were $2-4K US when I last looked... and would power the whole house indefinitely (but not as cheap as a standard utility...)

  23. VRLA = Valve Regulated Lead Acid by SuperBanana · · Score: 5, Informative
    I'm not familiar with what "VRLA" means, but unless the battery is sealed gel-type and rated for deep discharge and repeated cycling, I'd wouldn't use it.

    VRLA is Valve Regulated Lead Acid...VRLA is better than a sealed lead acid precisely because it will NOT explode- it will vent if charged too fast.

    VRLA is a teensy bit different from a standard gel cell in terms of charge profile, but they're close enough that it shouldn't matter much; I think the float voltage is typically lower. HOWEVER, you DO need to make sure you match specifications ( and not just "12v", get the specs sheet and look at the charge, float, etc voltages), and be aware that VRLAs are not particularly fond of heat; adding a tiny fan to the UPS enclosure would probably be a swell idea anyway as the buggers tend to run hot.

    The REALLY thorough will check the charge current from the UPS. UPS makers are under pressure to get the battery charged back up quickly, and they may push the limits of the battery's charge current. It's generally C/20 where C = A/Hr capacity; ie a 20Ahr battery should not be charged faster than 1A continuous (a brief peak charge might be OK, and if so, will be specified in current and duration). Charging too fast will cause gassing, overheating- and past a certain point, like many other batteries, lead acid batteries of any type can go into thermal runaway, which is not pretty.

    Adding in extra batteries into a UPS not designed for expansion will be trouble, on the charging side of the equation. If you've ever had a completely dead car battery and tried to charge it with a charger, you know what I'm talking about- the voltage drop is so great, the battery practically acts like a short and will cause the charger to overload. The same thing could happen with a UPS. A good sign is if there are battery expansion packs available for your UPS; use that as a guide for sizing.

    Oh, and by the way, you may want to consider adjusting your UPS to use the proper float voltage (not for the faint of heart, but possible on some UPS's without soldering), and again, installing a low-speed fan to move some air through the thing and keep everything cool. Many UPS vendors coughAPCcough set their float voltages too high and thus cook the batteries, and the elevated temperatures don't help either; that all makes for a nice revenue stream, as they charge a fortune for replacement packs(which are almost always made up of standard-size batteries, and thus available much more cheaply if you're the enterprising type). Properly maintained lead-acid batteries should last almost a decade- yet most UPS batteries die within a matter of 2-3 years. It's pathetic, considering how much lead is in them and how most people probably don't dispose of the UPS's or the batteries properly.

  24. Re:Car batteries by tylernt · · Score: 3, Informative

    "Dont put car batteries inside your home."

    At least explain why. Wet cell batteries vent (explosive) hydrogen when charging. That's why when you jumpstart a car you make the final connection to ground (earth) away from the battery. Too much hydrogen floating around the battery that a stray spark could ignite.

    Sealed gel batteries, which to not vent, are fine indoors. That's what most UPSes use.

    --
    DRM 'manages access' in the same way that a prison 'manages freedom'
  25. 250v 4 amps - 8Hrs...NO WAY on Batts by liquidzero4 · · Score: 2, Informative

    I'm surprised at how many people suggested the use of batteries and an inverter. The ammount of batteries that you need to provide 8hours of 250v at 4amp would occupy an entire garage. It would be a magnitude cheaper to just buy a gas/diesel generator.

  26. Re:furnace won't work with UPS, don't bother tryin by jlipkin · · Score: 2, Informative

    For God's sake, be careful if you use propane or any other type of heater that is not intended for indoor use. Burning propane generates carbon monoxide, which is deadly and odorless, so make sure that the heater you use is properly vented. New York City just passed a law requiring all residences to have carbon monoxide detectors, following the deaths of three women from co poisoning due to a faulty flue. A search of a newspaper database for propane heater carbon monoxie poisoning turned up 327 articles. Remember that in 1994, tennis star Vitas Gerulaitis died from a faulty heater.

  27. Re:furnace won't work with UPS, don't bother tryin by Fortress · · Score: 2, Informative

    get a propane space heater and a 20lb tank

    Don't do this. Catalytic propane space heaters are meant to be used in open, well-ventilated areas, like outdoors. Used in enclosed spaces, a dangerous level of CO2 can build, which can be potentially lethal. This is especially dangerous in an outage situation, where you're likely to huddle in a smaller, well insulated room and close the doors.

    Your best bet for an emergency heat source is a fireplace. Wood is good, but propane is simpler to operate, easier to install, and lower maintenace. It's safer than a space heater because it vents exhaust gases outside and the tank (usually larger than 20lb) is stored outside your home. Some models have a fan to use convective heating, making them more efficient. This fan is usually small and lower power, suitable for a reasonably sized UPS.

    It may cost a little more, but you also gain the aesthetic benefits of having a fireplace to use anytime, whereas the space heater is often an ugly looking contraption.

  28. US voltages by SIGBUS · · Score: 4, Informative

    Actually, typical residential service in the US is 240V split-phase; the distribution transformer is center-tapped, and the center tap is grounded to serve as the neutral. Phase-to-neutral is 120, phase-to-phase is 240. Heavy-draw appliances, such as large air conditioners, electric ovens, dryers, etc. are usually run on 240.

    Another system uses two of three phases on a 208V three-phase supply; phase-to-neutral is still 120. This is normally only found in apartments and commercial buildings.

    --
    Oh, no! You have walked into the slavering fangs of a lurking grue!
  29. Generator or catalytic heater by redsilo · · Score: 2, Informative

    Finally something on slashdot that I know something about. We went through a major ice storm here(Oklahoma) about 3 years ago. If heat is what you are concerned with get a gas catalytic heater in the 20k to 30k btu range. We had one on hand still in the box and hooked it up and lit it about the time the juice went off. We expected to keep a couple of rooms warm but were pleasantly surprised to find that it kept the whole house toasty for the 2 weeks we were with out utility electricity. Make sure you figure a way to hook it up to your gas service beforehand. We used an airhose tee'd into the line going to the furnace. It won't pass anyone's code but if you get in this kind of shape the authorities will have their hands full with other things. The heater is pretty clean burning but there is no flue so you need to go outside once in awhile just to make sure you change some air. We did eventually borrow a generator from family living outside the blackout zone. Neighbors bought generators by the hundreds. Most got 5KW models. They were able to run part of the house at a time - freezer and refrigerator and some lights or furnace and some lights when that was a priority. 10KW should let you live quite comfortably. The generator we borrowed ran off the PTO of a tractor and was 13 KW. We didn't run the furnace but kept using the catalytic heater. That way we could shut off the generator part of the time and still keep warm. The generator was an older model that had brushes and the lights flickered some but some of the more modern brushless ones flickered too. The only appliance that seemed to take exception to it was the microwave oven. When we tried to use it it sounded like it would come off the shelf so it stayed parked for the duration. Real electronics mostly run on rectified DC internally so the flicker gets filtered out. Had no trouble whatsoever with any of those things. People warned that months down the road troubles could arise but we have seen nothing that seems related to the outage. The heater we had was around $150US and the 5KW generators were $500 to $600. I don't think I would consider trying to do what you suggest with batteries. Both heater and generator will cost almost nothing in maintenance if you never use them but batteries will go bad no matter what. You know your situation best. There was at least on fatality from CO from a generator during the time we were blacked out, so that is something to be aware of. Some of the generators developed carburator icing problems when run for hours on end. They really weren't made for quite that kind of service but there were few if any outright failures. redsilo

  30. Oz is 240v too by DABANSHEE · · Score: 2, Informative

    But it's extremly rare to find anything made for any voltage between 220v & 250 that doesn't work or cause problems.

    Really other than things made for the US & other weird places, everthing made to run on mains for the last 50 years is to designed to run on any voltage between 220v & 250v wihtout a hiccup.

  31. Re:Oops.. by Technician · · Score: 4, Informative

    You're talking about 4 amps at 250 V, over a period of 8 hours. That's 1000 watts for eight hours, or 8 kilowatt hours. However, this doesn't cater for the power factor -- if your house has a power factor of 0.8, for example, batteries capable of providing that current for that period of time will run your house for about six and a half hours. So you'll need to bring up the batteries to 10 kilowatt hours to compensate -- either that, or (if it's an inductive load) buy a whopping great big bank of capacitors to bring the power factor back up to a reasonable level.

    Umm you got it backwards.. Lets go to the facts..

    Starting with some glossary terms..

    Volts = Electrical pressure
    Amps = Electrical current
    Watts = Power
    VoltAmps = Volts * Amps
    Vars = Volts Amps Reactive.
    Power Factor = Percent of Volt Amps that are Power scaled 0-1.

    What's it mean?
    If you drop a Capacitor on an AC line, it will draw current but not get hot unless it's not designed for the voltage, current, or polarity.

    The current is said to be reactive. All of the current measured in VA is not Watts. The power Factor is zero. Volts * amps * power factor = watts. Most inverters don't like a highly reactive load. This may dammage it.

    A light bulb gets hot. It is not an inductor or capacitor.. It has a power factor of 1. Volts * amps * power factor = Watts.

    A furnace motor may have a power factor of 0.8. If it drew 4 amps at 250 volts it's VA = 4*250 or 1000VA. The actual power draw in watts is 80% of tthe VA. Remember power = Volts * Amps * Power Factor or 250 * 4 * 0.8 = 800 Watts.

    So in the above example in the parant, the load draws 800 watts. If it draws it for 8 hours, that's 6.4 KWH not 10 KWH.

    Remember that inverters don't like reactive loads. The inverter may take the reactive power and dump it as heat depending on the design. That's 200 watts of reactive power. You also need to scale for conversion consumption. The inverter uses power. It is not a lossless process.

    If you run large reactive loads, save your inverter by looking into doing some power factor correction.

    With a reactive load such as a transformer or motor, the current lags the voltage. In a capacitive load such as a noise filter, current leads the voltage. It is possible to correct reactive load problems with lamp ballasts, motors and transformers by adding capacitors to the line. You want a capacitor that has the same VAR rating as the load you are trying to correct. In the above example, we have a reactive component of 200 watts. (800 true watts subtracted from the 1000 VA leaves the reactive component of 200 watts reactive) Adding 200 watts capacitive reactance will cancel out the inductive reactance load. This will reduce the load on the inverter. Now it sees a 800 VA load, not a 1000 VA load. Now the inverter sees a power factor corrected to 1. The motor still draws 1000 VA but now gets the 200 VA reactive component from the capacitor, not the inverter.

    I hope I didn't loose too many in the dry discussion of what a VAR is.

    Anyway, this is the reason on some power poles, you may see a bank of capacitors. It is used to correct power factor and reduce the amprage load on a substation.

    --
    The truth shall set you free!
  32. Re:Central heating for 8 hours? by Yotsuya · · Score: 2, Informative

    Poster said he had gas heating, but it's electrically-fired, so he does need electricity to run it... but he's not heating with electricity.

    --
    Claude Angers
  33. Your car provides everything you need. by Myself · · Score: 3, Informative

    Your car is a self-contained habitation module. Given a supply of dead dinosaurs, it'll produce plenty of heat and electricity. Here's how to get them out of the car and into your house. I haven't actually set this up yet but I've been considering it for a long time. Give a think to this plan:

    The electricity is pretty simple. Your stock alternator produces 14 volts DC at somewhere between 50 and 100 amps. After derating for alternator heating, and inverter losses, figure about 500 watts of useful continuous power, with momentary surge capacity of at least 2kW. Inverters that produce more than 100 watts or so should be wired straight in.

    For the heat, you'll need a way to circulate the engine's coolant into the house and back. Pick up a "radiator flush" kit at the auto store. It's a set of tee fittings that install inline with the radiator hoses, and have threads for garden hoses to screw on. Pick up a radiator from the junkyard, and a bunch of hose that can handle the temperature and pressure involved. Plumb your new radiator in parallel with the existing one.

    After filling the whole mess with coolant, doublecheck all your hoseclamps and start 'er up. As the engine heats up, the thermostat will open and both radiators should get warm. If you need to divert more flow to the external one, try pinching or adding a valve to one of the hoses. Put a small fan on your in-house radiator and voila!

    Now the only problem is that Murphy's law guarantees a power failure will happen when your tank is almost empty. Diesel keeps well, but gasoline turns to varnish after a few months in storage, so if you're going to keep a few gallons in a spare can, change it out regularly.

    (Please note: Make damn sure all your hoses and fittings can handle the temperatures and pressures involved. Check the coolant level after the bubbles work out. Keep an eye on engine temp if you choose to restrict the hose, and pay special attention if the engine's radiator fan comes on, which probably indicates inadequate coolant flow. Provide adequate airflow over the inverter's heatsink. Don't touch wiring with your hands covered in coolant. I'm not responsible if you blow yourself up.)

  34. Re:I suggest by jabuzz · · Score: 2, Informative

    Except the problem is that due to the insane policies of the last Consevative goverment we now use large amounts of natural gas to generate electricity in the United Kingdom. Shear utter madness really.

    The result is that if there is a cold snap that lasts more than two or three days there will be insufficent gas to provide for both electricity generation and domestic gas, and something is going to have to give. The only reason it has not happened before is that we have had a series of mild winters since the mid 1980's. The likely outcome is that domestic gas will be cut not electricity generation however.

  35. Used diesel power generator by pppjurac · · Score: 3, Informative

    The cheapest solution is to go around, find and buy used diesel power generator.
    Put it into a garage or cellar, connect exhaust pipes to outside, and finally get an electrician to connect it to house grid.
    Ok - they are big and noisy when started, but I've seen such solution and it works better than anything on led batteries, which tend to go down in really cold weather.

  36. Re:Need a generator? by StCredZero · · Score: 2, Informative

    Get a hyperefficient Whispergen Stirling generator. It would both heat your home and provide electric power by burning natural gas. In fact, if your meter is wired correctly, at times you would be selling power back to the power companies. You can think of it as augmenting your furnace heat with a 2nd device and getting electricity (in the form of your own off-grid generator) for free.