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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?"
Use a normal UPS to bridge the first few minutes in which you can comfortable start a generator.
21x twelve voltage batteries rated at 30Ah hooked up in series :)
-Foxxz
Oh, and drink whiskey. Lots and lots of whiskey. It makes good antifreeze for the blood :)
A fine is a tax you pay for doing wrong and a tax is a fine you pay for doing all right.
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
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.
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...
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.)
Only in a Slashdot fantasy can a Slackware install turn into several hours of sex . . . . .
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)
I don't need no instructions to know how to rock!!!!
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.
See also this detailed article on what kinds of batteries might do the job. good practicle info.
"It is a greater offense to steal men's labor, than their clothes"
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!
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.
Gods don't kill people, people with gods kill people.
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.
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.
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
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"
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
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
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.
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.
Please help metamoderate.
"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'
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!
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!
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.)
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.