How to heat the house during a power outage

I am looking for an inexpensive way to heat my house during a power outage.  I have a gas-fired furnace that heats steam for my radiators.  

I have an idea I want to try on people with more experience in such things.  I will get a small generator, or DC-to-AC inverter running off my car, and hook it up to my heating system.  

All I have to do is to get an electrician to put a switch next to the junction box that feeds household AC power to my heating system.  During a power outage, I will shut off the household AC power and connect a feed from the generator or the inverter.  (I would not run the car continually if using an inverter.  Just long enough to heat up the house.)    

The furnace does not consume much power.  There is a small electrical black box on the flue [I think it is for venting products of combustion] and the low water level sensor that run from the household AC power.  The thermostat feeds off its own battery, so it would be on during a power outage. 

If this sounds like a reasonable idea, do you know of a good electrician who could install the switch for me?  If it is not a good idea, please tell me why.

All comments most welcome!  Thank you.

There were a lot of long, detailed threads about generators and other approaches to dealing with power outages during and after Sandy. You might see if you can dig them up if you don't get many responses here.

Yes, get a generator transfer switch attached to your electrical panel. A simple one lets you connect a single circuit to something like you describe... an extension cord from an inverter.

You can also invest another $200-300 on a simple battery operated system to power that transfer switch without running your car. Get a marine battery and a battery charger to keep inside. I was able to keep my gas boiler running like that for several hours.  The advantage is you don't need to leave your car running.

I had a generator interlock installed at our NJ house, but the idea of leaving the generator running outside all night just to keep the heat on isn't appealing. I'd like to try something different for this house.

Can you make it through the night on just one battery? I've got to assume the boiler only runs an hour or two total any given night. I suppose I could just tough it out for an hour while things heat back up, but I'd rather not.  

During Sandy we used a small gasoline powered generator hooked into our boiler.  We did not run it over night, and were mostly toasty warm in our beds.  Getting out of bed in the morning was the problem.  It was cold, but we started up the generator first thing and it wasn't long before the radiators were hot.  

I think a separate battery to run the heat would only work in shorter power outages.  You would need a way to recharge it, which would mean a generator in a situation like Sandy, when we didn't have electricity for over a week.

your boiler ties into your wiring at a junction box.  Convert the junction box to a standard receptacle and add a standard plug to the line from your boiler.  Leave it plugged in to the receptacle unless there is a power outage, at which point you can unplug the boiler and plug it in to your inverter or generator, or your neighbor s house if they still have power.

If you warm up the house during the day, you can usually get through the sleeping hours OK with an extra blanket or two.  Those of us with setback thermostats do this intentionally most of the time.

Sleeping is fine, I'm worried about getting up and going outside and starting the generator just long enough to warm the house before I have to turn it off again and go to work. 

Thank you all for your comments.  I have a better plan now as a result of your input.

Any recommendations for an electrician who could retrofit the junction box to a standard receptacle and add a standard plug to the line from my boiler?

Your help is much appreciated. 

We purchased a generator. We have gas heat, but needed electricity for the thermostat to send the call for heat down to the boiler and for the boiler to turn on. Going nine days without heat during Sandy was difficult, but not impossible. More difficult was having to throw out an entire fridge and freezers worth of food, and as someone dependent on a CPAP, sleeping without it was torture. I slept sitting up right, and every night I had dreams that someone was strangling me. That was more than enough, and even though my sleep apnea has improved somewhat recently, I still need the machine and never want to be in that position again if I can help it. 

Also, during sandy we had an old style water heater with a pilot light, so we had hot water the whole time. Our new water heater is gas but is piezoelectric instead of having a pilot light, so without electricity we wouldn't even have that small luxury.

spontaneous said:

We purchased a generator. We have gas heat, but needed electricity for the thermostat to send the call for heat down to the boiler and for the boiler to turn on. ...

During a power outage, it is sufficient to replace the AC power source feeding the furnace.  

The thermostat usually operates at 24 V ac power, and the source of this control power comes from a control transformer mounted on the furnace body. The line voltage feeding the furnace (to operate the fan blower motor) is transformed down to a safer level of 24 volts, and the power goes up to the thermostat. When the room temperature falls below the set-point, the contacts close completing the circuit to the gas valve allowing it to open, the main burner to ignite, and begin the heating cycle.
http://www.electrical-online.com/thermostat-wiring-explained/

So this isn't code, no electrician will do this.  I did it myself during Sandy then changed it back.

You'll need a more "correct" solution with a transfer switch to be code compliant

mbb said:

Thank you all for your comments.  I have a better plan now as a result of your input.

Any recommendations for an electrician who could retrofit the junction box to a standard receptacle and add a standard plug to the line from my boiler?

Your help is much appreciated. 

Thank you Peteglider.  It is important to know that.

Then are there any recommendations for an electrician who could install a transfer switch between the household AC and the emergency power source (generator or inverter) for the line to my boiler?

peteglider said:

So this isn't code, no electrician will do this.  I did it myself during Sandy then changed it back.

You'll need a more "correct" solution with a transfer switch to be code compliant

mbb said:

Thank you all for your comments.  I have a better plan now as a result of your input.

Any recommendations for an electrician who could retrofit the junction box to a standard receptacle and add a standard plug to the line from my boiler?

Your help is much appreciated. 

mbb said:

Thank you Peteglider.  It is important to know that.

Then are there any recommendations for an electrician who could install a transfer switch between the household AC and the emergency power source (generator or inverter) for the line to my boiler?

peteglider said:

So this isn't code, no electrician will do this.  I did it myself during Sandy then changed it back.

You'll need a more "correct" solution with a transfer switch to be code compliant

mbb said:

Thank you all for your comments.  I have a better plan now as a result of your input.

Any recommendations for an electrician who could retrofit the junction box to a standard receptacle and add a standard plug to the line from my boiler?

Your help is much appreciated. 

Any good electrician should be able to do this.  Brian Stromko did mine. He is my go to electrician (and my neighbor.)

Thank you sac.

There is a small transfer switch made just for furnaces. Any electrician can install one. You then have to supply either a generator or a battery and inverter. Generators have to run outside so you don't kill everyone with carbon monoxide. Therefore, you have to run an extension cord from outside to inside. Also, the generator should probably not be out in the rain or snow unless it is weather proof. If you are going through the trouble and spending a bit more money is not a problem, I would have the electrician install a 6 or 9 circuit generator sub panel with an outdoor plug for the generator and buy a Generac portable propane generator that runs on barbeque propane tanks. That way, you can backup your fridge/freezer and heating system and have lights too!

If by "furnace" you're referring to a steam boiler, then you don't need a generator. You only need a power inverter to plug into your cigarette lighter to keep it going.