Snow

[hufnagel]

Yea I already have the main panel set up with an interlock to backfeed. The question I can't seem to get a good answer on is if I put a separate power source, I know I'll have to lift both hot legs, but what about the neutral. I can't guarantee or enforce that both generators are in phase, and I sure as hell don't want shenanigans going on over the neutrals because of it. Then there's the control signal wire(s) between the condenser and the blower. Really don't want to let the magic smoke out of anything.

[RevolverRob]

Yea I already have the main panel set up with an interlock to backfeed. The question I can't seem to get a good answer on is if I put a separate power source, I know I'll have to lift both hot legs, but what about the neutral. I can't guarantee or enforce that both generators are in phase, and I sure as hell don't want shenanigans going on over the neutrals because of it. Then there's the control signal wire(s) between the condenser and the blower. Really don't want to let the magic smoke out of anything.

(note: ASSuming you don't have a heatpump here)

The signal wires between condenser and inside blower are low voltage (~12v) and most furnances (anything newer than 20 years) will have at least one, if not two fuses in parallel on the circuit board that will pop from too much input voltage. If you're on single phase power and the furnace and condenser are on separate circuits (like they are supposed to be according to code). Then you should be fine. Assuming single-phase power again, your furnace needs probably 20amps max to run. You can plug it into an extension cord and let it run constantly, without concern.

Remember that the A/C system is basically just a radiator on both ends. In the house, it's an evaporator system, where warm moist arm is blown across a radiator that is super cold (via the refrigerant). The refrigerant functions, basically like a heat sink, evaporation occurs, simultaneously the refrigerant heats up. Refrigerant gets to the evaporator via low pressure suction and high pressure return. The "compressor" inside of the condensing unit functions basically as a one way pump basically always sucking coolant back to it. The hot refrigerant enters the condenser, which is an actual, factual, air cooled radiator. Heat is dissipated, and cold refrigerant is returned back to the evaporator.

Because of the way the system functions, the condenser does all of the heavy lifting. The furnace in the house provides only the fan portion of this (the supply and return air). If the blower isn't running, the condenser doesn't really care (in the short term), it just will never cool off in the house. In the long term, running sans a blower will cause the system to freeze up (refrigerant is so effective if some heat isn't introduced to the system it will begin to ice). In practice this takes hours not minutes to occur. If there is no power to the furnace to activate the blower, the thermostat can still run the condenser, without any ill effect (and vice versa for that matter).

ETA: Oof, realized I was conceptualizing it as one generator running the A/C only and the other running the house. If you're running two generators into the main panel, then I'm outside my lane. If you want to run the entire HVAC system on one generator, just isolate the circuit the furnace is on and tie it back to your sub-panel. You could, alternatively run a separate circuit from your sub-panel to the furnace and junction it in. One side will be hot on normal power and dead on the sub-panel, and flipped when you shut it off in your main breaker box and energized via the sub-panel. The neutral issue, I wouldn't worry too much about. If you've got a good neutral ground at the A/C condenser you'll be fine. About 50% of the furnaces I've seen over the years were two-wired without a "neutral". That said, I'm not that good with electrics, so you know you might want to consult an electrician.

Hope that answers the question. My grandfather and father were both primarily HVAC contractors with a combined experience of 110 years. Family biz was general contracting/HVAC contracting until my father "retired" four years ago.

[Trigger]

Well....... the sidewalks here aren't that wide😁 I do three houses every snow and two of them live on a road that gets plowed. I'm too old for that shit plus my helper has gone off to college. And if I get a plow I'd have to get a truck. It doesn't matter what you talk about on this forum. It always cost money and it's never cheap.

Truth. PF signature quote material right there.

[Hambo]

I was looking at houses in Florida earlier. There is no snow outside currently (the 3" or so we had melted earlier in the week). But that won't stop me from dreaming about moving someplace where 3" of snow is "a lot".

Three inches of snow in Florida isn't "a lot", it's the end of the fucking world. As it is the iguanas lock up when it gets below fifty degrees.

[hufnagel]

@RevolverRob no I'd be isolating the condenser from the main panel, and essentially running it on it's own dedicated generator at that point. Interesting idea of isolating the furnace and condenser to their own generator as a pair, but as you noted the furnace is 120v and the condenser is 240v, and I'm worried the imbalance might piss the generator off enough, not to mention that a near 9000W generator is already maxing out to kick over the condenser (I know that running load is different than starting load.)

[11B10]

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Note the corner of the tool box sticking out of the snow. Same one as in above picture. Was all hard packed drifted snow. The floor is about 8 inches below where the snow stops in the lower pic, its a step over threshold. It was about 3 feet deep when I opened the door after the wind stopped. Pic was after I kicked and shoveled it out some so the dog could get out. I. Am. Sick. Of. It. I hate snow.

Attachment 33097

The rest of us have no right to complain!

[hufnagel]

The rest of us have no right to complain!

But we'll do it anyways. Because 'MURICA!

[Shotgun]

Calling for maybe 20" here. Not gonna be a lot of fun since the county doesn't do our gravel roads within the subdivision and not much of the land is level.

Just wondering how many of us here are waiting on a big ol' pile of snow this weekend?

Hope the power stays on. (The joys of well water, septic tanks and propane furnaces.)

Stay safe Brother Blues! We had snow in Dallas once; it even stuck to the roof tops. Shut the city down for a week.

https://www.youtube.com/watch?v=mN7LW0Y00kE

And, since it seems you will have a little extra time in the house (if you still have power), maybe you can explain to me how to attach a youtube video so that the vid shows up rather than me just attaching a link.

[11B10]

But we'll do it anyways. Because 'MURICA!

huf, you're so right. BTW, I am the king of thread drift and I would like to say that I've always loved the stuff at the bottom of your profile. Your "life philosophy," as it were.

[hufnagel]

huf, you're so right. BTW, I am the king of thread drift and I would like to say that I've always loved the stuff at the bottom of your profile. Your "life philosophy," as it were.