furnace with power out

[Terry]

I have a 3 year old hot water furnace. Natural gas fires a boiler and the water is circulated around the house with a small motor with pump. We are having more and more power outages here and winter has started.

So here is the question. Is the following a problem. What I would like to do is get a small generator. When the local 120 V power goes out, I'd like to disconnect the furnace AC from the house power and plug it into the generator. I figure a 2 Kw generator ought to do it. Of course the generator would be kept outside so I don't gas myself and family.

Is there a problem with this?

Terry

[John]

Should work fine provided you have a positive way to disconnect from the mains everything you are powering from the generator.

[John McGaw]

The typical circulator pump and boiler control electrics may consume even less power than you think. Mine in Alaska, using a Grundfos pump, ran easily on the smallest portable Honda generator. I know of people who ran theirs from inverters and truck batteries in a pinch. Otherwise, no problem at all as long as you have an absolutely positive disconnect mechanism -- I simply added a cord and plug to my boiler so that unplugging it from the dead wall socket and plugging it into the extension cord to the generator made backfeeding impossible.

[Stormin Mormonn]

I think you've got a good idea. The challenge will be to keep enough gasoline on hand to be useful. But, what the heck. If it gets you through several days, that's better than you had before.

I've used my little 2200 watt generator more than once for people. Furnaces are supposed to have a disconnect box. You pull it apart, and take an old appliance cord off a junk washing machine or microwave or whatever. Wire it to the furnace wires with wirenuts, and plug into the extension cord you ran in from the generator.

[George Elkins]

How long are the power outages? It may be possible to run a small circulation pump, boiler controls, etc. on a UPS for quite a while, but I haven't investigated the details. An electrician may be able to wire a UPS into the circuit. This might be less costly than a generator and has the advantage of requiring no manual intervention.

[m Ransley]

Boiler circulator- pumps typically take 150 to 400 watts for large residences ,boilers 100 to maybe 500 watt. Check your load first . You can do what you suggest but in generators you get what you pay for. Cheap unregulated voltage units can swing 45 volts or more from no load to full load. And HZ swings to. Many motors wont start unless

60Hz is there. Electronics can be ruined also. Cheap units are really for outdoors work, saws etc. Honda is expensive but the electronics are superior to ALL other small units. And the motors are tops. A 300 $ 6 circut transfer kit from Generac at Lowes is the way to go, its a complete system. Transfer panels make generator use safe . Dont let the generator run out of gas that can damage the Capacitators on your boiler motor , if it has any , and other motors, Fridge etc.

[m Ransley]

The problem with a Ups is it has to be big enough to handle surges of

400% of load for the motors, The cost then puts it in the range of a quality generator , Which will run as long as you have gas and be more flexible.

[Joseph Meehan]

Good plan, but that generator should be able to handle the frig, TV and a number of lights as well.

[CBHvac]

And electrocute the man working on the line outside the house since you were too stupid to flip the main and isolate the home from the main grid.

Man..you scare me.

[Terry]

Ok, the replies sound supportive. I can get into the disconnect box at the furnace to wire in. Also, there is a switch to cut off from the main above the furnace already. I don't need to power much more that the furnace. I don't mind sleeping in the dark or using candles, oil lamps for moderate light. The fridge can take care of itself as long as I keep my hands off the door. I have an outdoor gas grill if I need to cook a meal or two (wife wants only electric stoves -- bummer). So dealing with the furnace was my main concern.

Thanks for all that replied.

[Joseph Meehan]

You need to use a switch designed for this use. It needs to provide

100% lockout from the main power supply or 100% lockout of the backup power supply so there is no way you, or anyone else, can have both on at the same time.

I don't know if there is anything available designed for a single point application like yours. Most seem to be for whole house supplies.

Note: this is a real safety issue all the way around and in many if not all areas is required. This part of the process is important enough, and easy enough to screw up, that I suggest hiring a professional to do the hookup.

[Art Todesco]

[Tom Horne]

If he converts his heating plant electric supply to cord and plug supplied he does not need a switch. A plug cannot be in two different receptacles at the same time so the positive transfer function is taken care of. It may be a technical violation of the NEC to cord and plug supply a heating plant but it does not create any real hazard.

-- Tom H

[m Ransley]

Tom that would work on the furnace. Spending that much on a good generator though thinking ahead for lights and other things is a good idea. but he will get by and get heat.

[HT8687 c/o General Delivery]

If you reread the entire thread you will see that what is being talked about is replacing the disconnect switch with a receptacle and wiring the heating plant to a cord and plug. That provides an absolute disconnect between the homes wiring and the heating plant. The cord cap cannot be plugged into two places at once so there is no risk of back feed.

The reason so many of these discussions generate more heat then light is that so many of us are prepared to assume the worst about another posters intent.

-- Tom H

[Joseph Meehan]

While reading the original message, I would say your interpretation is the most likely, but I don't believe it is all that clear. Given the possible consequences of an error, I believe the advice given was warranted.

[Tekkie]

HT8687 c/o General Delivery posted for all of us....

And knowledge and workmanship and information given and lack of research on previously posted questions.

We are usually rewarded in our skepticism...