Use the car as a temporary generator during black out ?

That would probably work. But here is the secret - in any generator the driving engine is rarely the most expensive part.

I'll bet you could find a power plant/generator pair where the power plant is shot for cheap.

Reply to
Tony P.
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Getting the generator is the easy part. Getting it connected to your house in a safe manner can be much harder and potentially more expensive.

Most furnaces are hard-wired to the breaker/fuse panel - there is no cord you can unplug and plug into the generator. Making a "suicide" adapter with a plug on each end is not a good way ;-)

=========================

There are also non-electric ways to heat, light and cook.

A 22,000 BTU kerosene heater can heat 800 to 1000 sq ft on 3 to 4 of gallons of kerosene per day.

The heater is about $120, kerosene is about $1.75/gallon.

A windup/solar am/fm radio (FreePlay) is about $70.

Camp stoves (Coleman) are under $100 and propane cylinders for a week's cooking might be $10.

================

I'm not an off-grid person, I just happen to be prepared for the most likely local problems.

I bought a kerosene heater in 1999 used it for the first time in January 2000 (during an ice storm - 36 hours without power is the longest so far).

I also have a older Coleman stove and lantern (left over from camping with the kids) that use liquid "stove fuel" (basically low octane unleaded gasoline) and my wife has several (mostly decorative) oil lamps - but they always have a little fuel in them. Cooking on a liquid fuel stove is something of an art, but I make great omelets ;-)

Oh yes, the home network and DSL have over an hour of backup from a small UPS. There's also a car charger for the laptop. I have been known to use the laptop by the light of an oil lamp ;-)

More about me:

formatting link
source code:
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for the Palm with NS Basic source code:
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for Pablo graphics tablet and JamCam cameras:
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at@at mindspring dot.dot com. Fix the obvious to reply by email.

Reply to
the Wiz

It's not a completely silly question but you may conclude that this isn't the best approach either.

The gadget that converts 12-ish V d.c. into 120V a.c. is called a "power inverter." Punching that term into your favorite search engine should yield plenty of websites about them. People use 'em to run

*small* 120V appliances in their car or sailboat or wherever. Doing this is pretty inefficient, so the inverter sucks a lot of input current and gets nice and hot.

Small ones (few hundred watts steady-state, a bit more than that peak) are ubiquitously available for as little as $30, but those are best thought of as a way to let the kids play video games in the back seat, or perhaps for you to run handheld power tools at a jobsite.

Bigger ones can provide as much as a few kW steady state, but we're now talking about prices that start well into three figures and run into the four-digit range, especially if you want gourmet 120V comparable to what the power company delivers, rather than "close enough for government work" stuff.

The big ones also drain a battery in a big hurry, and are really happier with a jumper-cable-style or (robustly) hardwired connection than with the cigarette lighter outlet. The usual recommendation is that you keep your car running while using them and/or employ a separate, deep-cycle (marine-type) battery.

Your proposed application would need one of the huskier ones -- a residential furnace often has a surprisingly substantial motor, 3/4 or even 1 hp; and motors usually aren't too happy with either undervoltage or trashy waveforms. Some advise allowing as much as 3x the steady-state current draw at startup, so check the peak as well as the steady-state specs of the inverter.

You might well decide that either there's a cheaper way to get AC in a power outage or there's a better emergency way to keep the place warm...

Cheers,

--Joe

PS. Also, educate yourself on how to properly hook up and use a generator or other alternative AC source so you don't throw it into the teeth of an overload... or (eeek!) energize a line that somebody assumed to be dead. (Yeah, we all know what they say about "assume," but accidents happen somehow...)

Reply to
Ad absurdum per aspera

And somewhere around the time of 02/18/2004 13:53, the world stopped and listened as JW contributed the following to humanity:

What you have asked is not a stupid question, but alot of people have thought along the same lines that you have. Yes, and no. It depends on how much electrical power the furnace needs in order to start and run the blower. If your alternator/battery can supply the power, then great. Otherwise, you may want to invest in a real generator.

Reply to
Daniel Rudy

andy snipped-for-privacy@hp.com (Andy Hill) wrote in news: snipped-for-privacy@4ax.com:

You'll want to check that again.

Reply to
Bert Hyman

According to Bert Hyman :

Indeed.

Most of the forced air furnaces I've seen use 1/4 or 1/3HP blower motors, occasionally 1/2HP.

Even a very poorly efficient 1/2HP shouldn't be more than about 7 or perhaps 8A. A gas generator should be at least double that to drive the blower, and an inverter, probably triple.

Reply to
Chris Lewis

Sometimes when one pulls numbers out of one's *ss, they stink a bit. OK, overstating the case a for a residential furnace. Still strikes me as a marginal idea, at best.

Reply to
Andy Hill

andy snipped-for-privacy@hp.com (Andy Hill) wrote in news: snipped-for-privacy@4ax.com:

For a ->true emergency, it might be OK. But, an inverter with enough oomph to handle the motor starting loads would still be a big purchase. If you're serious about this, spend the bucks and get a real generator and a real transfer switch.

All this has a certain immediate interest to me since I was awakened at 4AM today by the shriek of my CO detector as it died from a power outage. Power's back on now (I called home and the answering machine picked up), but next time, who knows?

Reply to
Bert Hyman

Reply to
Art Todesco

I'd guess that the full-load or startup amperage on the motor could be that high, but I doubt many furnace blowers would take that much current once they were running..

Reply to
Robert Hancock

I wonder if one of those hybrid cars could be modified to run an inverter off its battery pack.

Reply to
R

According to Robert Hancock :

The usual plate ratings on motors are "worst case full load" (delivering full rated power under worst case manufacturing tolerance and supply voltage).

An efficiently matched motor and blower will be pulling "full load" (not necessarily "worst case", but close) amps all the time. This goes for pumps and compressors too.

Startup surge is 2-3 times that (and not listed on the plate).

In other words, a 10A blower motor _will_ pull close to 10A continuously.

20-30A startup surge.
Reply to
Chris Lewis

When there was a huge ice storm that knocked out the grid in Quebec and Ontario a few years back I mused about the same problem, how to get the furnace running without power and avoid the freeze damage to my home, any home.

This is a thought experiment. I have a natural gas central heating system. The thermostat and gas valve system works off a small 24Vac transformer. The fan motor is 1/2hp 115Vac. Its not too hard to jury rig a stationary exercise bicycle to turn the furnace blower fan and get the air circulation going. If I hook up a 12 Vdc car battery to a small 115Vac inverter thence to the 24V transformer can I get the furnace going and the house heated in an emergency? Can the furnace valve system work off 24Vdc (two car batteries)? The power draw on the battery to run the 24Vac parts is minimal so it shouldn't be necessary to use the car to recharge the battery often.

Reply to
KLM

Consider permanently replacing the blower motor with a 24Vdc unit and a transformer/rectifier for ordinary use. A sturdy bank of car batteries can power your heating plant often enough to keep a house from freezing for several days. A small inverter (400 watts is less than $40 at Sams Club) can power the control system.

OTOH it doesn't take a very large generator to run a furnace. Natural_gas/propane fired is advised.

Reply to
Bill Vajk

That's interesting. My oil-burner furnace is on a 15 amp circuit breaker. The largest draw seems to be greatest when the oil pump fires up, not when the blower starts up. I don't think the typical furnace blower motors are even close to 10A running.

Reply to
James C. Reeves

--------- The problem will be "how long can you drive the fan effectively" 2 minutes?

5 minutes? What condition are you in? A nominal figure for a human is (was? ) about 1/7 HP continuous. Estimated air flow less than 10% of normal.

-- Don Kelly snipped-for-privacy@peeshaw.ca remove the urine to answer

Reply to
Don Kelly

The AC output of automotive inverters should be good enough for that. The usual automotive inverter output is what they call a "modified sine wave", which is more like a "modified square wave". The RMS value of the output is 120 VAC or reasonably close. The waveform goes like 3/8 cycle positive, 1/8 cycle zero, 3/8 cycle negative, 1/8 cycle zero. The RMS voltage of the 60 Hz (or fundamental frequency) component alone will be a little short of 120 VAC (or tal RMS voltage), and lamps that use ballasts may run a little dim. Motors will be not quite full blast and may give noisier vibrations from the harmonics but will basically work, and should not have trouble unless they barely work with true sine 60 Hz full 120 VAC. I imagine a motor will heat up a little more with the different waveform with "slightly wrong" RMS voltage of fundamental frequency compinent alone, although this should only be a big deal if the design or condition of the motor and/or the equipment using it is already marginal. DISCLAIMER - NO WARRANTY BY ME, especially for monetary amounts in excess of fees that I get from you for making this post. :)

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

"Don Kelly" wrote in news:FMb_b.579043$JQ1.480055@pd7tw1no:

And who is going to stay up all night to ride the bicycle periodically to keep the furnace working?

I suggest a more practical thought experiment would be to power the furnace blower from the same 115vac inverter that runs the thermostat and gas valve, keeping the 12vdc battery charged running the car engine.

Oh, and if you're enchanted with pedalling a bicycle to save energy, hook an alternator to it and charge the battery. And don't forget the body heat you'll generate pedalling... that'll warm the house too. Or at least it'll warm you....

Reply to
Jim Land

  1. The exercise is less to keep the house toasty. It is more important to keep it just above freezing so that the water pipes, toilet tank, etc. don't burst. Then there are the house plants and things I haven't thought of that will be damaged by freezing. Room temps. of 5 to 10 deg above freezing should do.

I can always keep warm with soup and hot meals made on the propane BBQ and the camper stove. I don't have trouble keeping awake at odd hours.

  1. My house is quite well insulated and the furnace, even at minus
20deg C outside, doesn't require the furnace to be run continuously. If the problem is that bad that I need to stay up and pedal every 20 minutes or so, so be it. Power out should not last more than a day or two. If more days I would already have more than enough time to drain the water pipes and take care of the other freeze sensitive items. Consider the alternative that freeze damage may run into thousands of dollars, not getting enough sleep for a few days is a cheap price to pay.

  1. The furnace blower is quite easy to turn by hand. I am in good shape and can keep on the bicycle for hours at a leisurely pace. I don't need to pedal that fast. All I need to do is to keep the furnace air moving so that the thermocouple sensor interlock remains cool enough to keep the gas supply going.

  2. In my thought solution the parts and set up required are minimal. A small inverter costs under and the car battery I already have. I cannot hook the furnace to the car directly without having to run at least 100 feet of heavy gauge cable (re. arguments made by others) and I can't justify keeping one around for an unlikely emergency.
Reply to
Klm

Hmmm. That's an interesting idea. Who are the quality names in NG and/or propane-fired gensets?

Reply to
Andy Hill

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