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Gas furnace on generator question

5K views 17 replies 11 participants last post by  beenthere 
#1 ·
Ok folks, need some input here. I've hooked my gas furnace up to be able to run off my generator by following Rick's DIY on YouTube (sorry first post so I can't post links). The basic setup is using an appliance extension cord to power the furnace with a single plug outlet so that the furnace can be unplugged and plugged into generator. Also, my furnace is on a dedicated circuit.

On my setup, I have an emergency shutoff switch that is fed by a box in the ceiling directly above the furnace (attic above, romex cable exposed). I installed the outlet below the switch and thinking I might be wrong. In the event of a power outage, how would the thermostat receive power? Would having power go to the furnace from the generator also provide power to thermostat? Also, would it be wise to turn off the breaker? I don't want to risk having the generator running and the power come back on. Should I have put the outlet above the shutoff switch?

I also considered installing a Reliance Furnace Transfer Switch but have the same concerns. Where would this be installed in line? Above shutoff switch, below? Or would I knockout a hole in the box the shutoff switch is on and feed it into that and tie everything together inside that box? I can add pictures in necessary.
 
#2 ·
Every modern HVAC system I have ever seen has the transformer located inside the blower cage. Supply AC to the furnace powers the transformer which uses the thermostat wire to power the thermostat.
 
#4 ·
Ayuh,.... Not that I would advocate breakin' codes of any sort, any where, any time,....
In a life or death situation,...

You plumb in the generator, between the switch, 'n the furnace,....
In the event we're talkin' 'bout, you'd turn the switch Off, to break the connection to the grid,....
Then plug in yer generator,....

Before ya ever try this,....
Flip the Main Breaker at yer electrical entrance, for safeties sake,....
Even though the switch at the furnace is Off,....
When a generator is hooked to a house, the Main, absolutely has to be Off,...
 
#6 ·
as long as it does not have a mechanical governor/speed control like your basic Honda/Coleman. If it has a electronic speed control or converts the power and they guarantee the frequency/hz/hertz and voltage are stable then it may be safe. If the voltage or hz drops then your board will get damaged.
 
#12 · (Edited)
I have a Yamaha inverter generator hooked up to a transfer switch connected to essential circuits including the one for my modern high efficiency gas furnace. These generators control voltage and frequency electronically so they do not vary with engine speed. And because of this many of them are designed to run at slower speeds than conventional generators so they are quieter and easier on the engine. On this generator my furnace runs as normal.
 
#13 ·
Ok folks, need some input here. I've hooked my gas furnace up to be able to run off my generator by following Rick's DIY on YouTube (sorry first post so I can't post links). The basic setup is using an appliance extension cord to power the furnace with a single plug outlet so that the furnace can be unplugged and plugged into generator. Also, my furnace is on a dedicated circuit.

On my setup, I have an emergency shutoff switch that is fed by a box in the ceiling directly above the furnace (attic above, romex cable exposed). I installed the outlet below the switch and thinking I might be wrong. In the event of a power outage, how would the thermostat receive power? Would having power go to the furnace from the generator also provide power to thermostat? Also, would it be wise to turn off the breaker? I don't want to risk having the generator running and the power come back on. Should I have put the outlet above the shutoff switch?

I also considered installing a Reliance Furnace Transfer Switch but have the same concerns. Where would this be installed in line? Above shutoff switch, below? Or would I knockout a hole in the box the shutoff switch is on and feed it into that and tie everything together inside that box? I can add pictures in necessary.
Is the furnace install in the attic , your transformer is probably hard wire out side the furnace and not getting power to step down to 24 volts for your thermostat. The generator need to get power to your thermostat first than plug your blower.
 
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