I just run 120v extension cords from my EV during power outages (it has 2 15A capable outlets). I added a manual transfer switch to my furnace so it can be plugged into an extension cord, and I can power my furnace, blower, refrigerator and freezer, wifi and internet for a couple of days.

I really wanted to set up an automatic transfer switch for the whole house from my car in v2h mode, but I found it impossible to spend any amount of money and be confident that the system would actually work with my current EV (the wallbox quasar _sounds_ promising but I couldn't find any reports that it actually _works_)

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DenisM a day ago | parent [-]

Is that the transfer switch just for the furnace or the whole house? I was staring at my furnace yesterday, trying to figure out what to do if power stops and temperature drops below freezing. Doing the whole house transfer switch is too much, esp given o don’t have a 30amp power source, but it never occurred to me to do just the furnace.

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Johnny555 a day ago | parent | next [-]

I had a transfer switch installed just for the furnace.

https://www.reliancecontrols.com/products/reliance-controls-...

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turtlebits a day ago | parent | prev | next [-]

Hacky way is to install a plug on your furnace that you can connect directly to a generator or power station. Takes maybe 5$ in parts and is DIYable.

Lots of tutorials on YouTube.

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caymanjim 18 hours ago | parent | next [-]

Don't do this. Install a transfer switch. A simple plug and another power source feeds power back into the grid. It's absolutely against code. If you remember to flip the furnace breaker off before you do this, then it's not going to backfeed, but this isn't something you should rely on remembering to do. It doesn't cost much more to do it right.

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turtlebits 4 hours ago | parent | next [-]

It's not against code in all locations. You're essentially adding a power cord to your furnace and turning it's existing panel connection into an outlet.

Eg, in North Dakota

"If manufacturer instructions allow the use of not more than six feet of flexible appliance cord, it shall be permitted on permanently installed one hundred twenty volt twenty amp or less fuel-fired furnaces in residential dwellings."

https://www.law.cornell.edu/regulations/north-dakota/N-D-A-C...

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jefftk 12 hours ago | parent | prev [-]

I think they're proposing switching your furnace from hard wired to plugged, so you have the option to power it either from an outlet (grid) or solar/generator/etc. This can't backfeed the grid, and is very safe.

It looks like when it's against code it's "by default": if an appliance is not explicitly listed as acceptable for a plug it has to be hard wired. ND and OK have passed state level amendments allowing it, some places have done this locally, and in many places building inspectors allow it with their discretion.

	▲	caymanjim an hour ago \| parent [-]
		Yeah, maybe I misread. Switching it manually via a plug such that it could only ever be powered that way is fine (well, "fine" insofar as it alleviates my concern). I thought the suggestion was to add the new plug in addition to the permanently-wired solution. On a beast of a HVAC system, a simple 15A wall plug isn't going to cut it for powering the whole thing, but if the furnace runs off e.g. natural gas and you just want to power the blower off a 15A plug, that solves the problem of switching power sources.

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jerkstate a day ago | parent | prev | next [-]

Sounds not-up-to-code and potentially dangerous

	▲	caymanjim 18 hours ago \| parent [-]
		Because it is both.

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DenisM a day ago | parent | prev [-]

Makes sense. My mind went into a less safe direction, I’m glad I asked before following it.

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a day ago | parent | prev | next [-]

[deleted]

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quickthrowman a day ago | parent | prev [-]

Here’s how you’d set up just your furnace to allow a generator to power it in a permanent way.

For the transfer switch, you can use either a single-pole double throw motor rated switch for a 120V like a Leviton 1285, or a double-pole double throw motor rated switch like a Leviton 1288 for 240V. It must be motor rated.

You’ll also need a power inlet and a cord that connects between your generator and the inlet. Please buy a premade cable and the proper inlet, do not hack together a cord with two male ends aka a suicide cable that you plug into a standard outlet. Example of a safe setup: https://www.vevor.com/power-outlet-box-c_12116/vevor-30-amp-...

Wire the generator inlet to one side of the switch and connect the other side of switch to the utility fed circuit.

Label the switch positions so you don’t forget.

When the power goes out, flip your switch to the generator side, connect your generator to the inlet and turn it on. When the power comes back, flip the switch back to utility and turn off the generator. The center position of the switch is off and it’s impossible to backfeed the utility under normal conditions.