Forum Discussion
Huntindog
Mar 16, 2014Explorer
Gdetrailer wrote:The furnace uses 12 volts. The method of AC grounding has no effect on it.
A couple of things..
Contractor gens like the Coleman typically supply 240/120V. This is accomplished by having two separate 120V "windings" in the gen head.
The windings are wired in series to provide 240V and the 120V is tapped using the center point of the series wiring.
Typically on this setup the AVR (automatic voltage regulator) is connected to only ONE of the two windings.
When heavily loading only one side of the 120V windings which does not have AVR it will cause a voltage sag. To fix that sag you need to add a load to the opposite 120V winding (outlet)and the voltage will on both 120V windings will be corrected for the load.
You also only get HALF the rated wattage on the 120V outlets with the typical contractor gens. The Champion on the other hand should have a switch which combines both 120V windings properly to give you all the rated wattage on the 120V only outlets (you lose the 240V when the 120V only mode is enabled).
Additionally modern furnaces tend to have a rather picky control board and depending on the type of fan motor your furnace has it may or may not run correctly.
If fan is a variable speed fan, it may not like the waveform, frequency or voltage variations which happen with a generator.
The control boards also will do a system check when power is applied, part of this check is to verify that the neutral (white) and ground (green or bare) are "bonded" together. If no bond is detected (IE open between the two) the board will lockout and prevent the furnace from operating..
The reason I mention this is some generators do not connect the neutral to the ground and some do..
If you connect the gen through your breaker box the neutral and ground are bonded in the box and the furnace control board should be happy..
BUT please, do not "back feed" your breaker box, it is dangerous to you and your family AND the power company linesman.
By "back feeding" I am talking about not using a proper TRANSFER SWITCH or the proper interlock which forces the main panel breaker into the off position when powering the panel via a generator..
Back feeding via a double male cable which is often called a "dead mans cord" is also a bad idea..
DON'T DO IT, there IS a reason that you can not buy power cords with a male end on both ends.
Power cords are designed with a male end to plug into a outlet and the female end there is no exposed electrical connection that you can touch..
Install the PROPER generator INLET connector (a generator inlet connector prevents you from making contact with any live or hot pins) with the proper transfer and be safe..
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