Unsuccessful...Running Furnace off of Generator

Good Afternoon Gentlemen, a few months ago we had a power outage that lasted several days. We decided to setup our house to run the essential items off of a portable generator. All seemed to be well until we tried to fire up the furnace and we received the error code b6: Blower over/under voltage or over temperature trip. While on generator power, I used a multi-meter to check the voltage and it read 126 volts. I flipped back over to power company power and the furnace fired right up. I checked the power company power voltage with a multi meter and it read 124 volts. Is there something I could install before the furnace that would clean up the power to allow the furnace to run? We just installed an identical setup in my parents house the previous weekend and everything worked fine. The only difference is his furnace is about 20 years older and has a lot less electronics.

As a side note, during the power outage a few months ago I tried running my furnace off of a yamaha inverter generator and was only able to get the furnace to run one time. I kept getting an improper grounding fault code. My parents furnace had no issues whatsoever running off a pair of honda inverter generators.

As always, Thanks for your input.

Try turning on some lights and maybe an electric heater to load the generator and drop the voltage.

Does your generator produce a sign wave or sawtooth wave? Electronic circuits don't run well with a sawtooth wave. Check with the generator manufacturer on that.
Is the generator connection properly grounded?
I would also ask the furnace company about this. I run my 90+ furnace off my generator with no problem.
I connect my generator to my service panel with a 220V input so I can run anything I want as long as I don't exced the max generator load. . Are you running 220 or just 110?

Dave

A uninteruptable power supply will isolate the generator from the furnace providing clean power to it from a generator. It might be easier/ cheaper to get a different Generator. Jim

We used to run our gas furnace off a little Coleman 2500 powermate, a cheap little generator, but it was a 25 year old furnace, probably not as fussy as yours. I like Ozlander's suggestion, but I would use an induction motor for load, it might smooth out the sine wave. The place I retired from used to leave some large motors idle all day, they said it smoothed out the power, they were 5,000 hp synchronous motors, starting them used more power than idling for a long time.

I was thinking of that too.
Has to be an UPS with a true sine wave or some types of modified sine wave .
We have tried to operate some systems at work from UPS systems with varying degrees of success .

Newer electronics don't like cheap Gen power.

As mentioned try a UPS and see if that helps,
Or invest in a better Gen Set.
Providing everything is wired correctly.

I just replaced my HVAC Unit couple three years ago.
All kinds of electronics.

My older 30KW Cummins/Onan runs it just fine

Good Luck
Tom

It might be a grounding issue. Mine wouldn't work until I connected the neutral and ground in the furnace cord cap.

Power is probably not clean enough.I had that problem with larger generators. Changed the regulator to an updated version. Problem was solved. Power from small units is not always the best.

Yup, bet that will do it.

All he’s talked about is 120. I wonder if he’s trying to run the furnace on 120 instead of 240?

-Scott

This is a very common complaint that has basically only shown up since the advent of the small portable inverter generators.

The fix is very simple.

Your furnace needs to see the neutral power lead and the ground lead from the generator connected together.

With all of the Honda EU series of generators and most of the Yamaha inverter generators, the ground lead from the generator is "floating", not connected to the neutral.

Your furnace needs to see those two leads connected together.

Apparently you are attempting to run your furnace on an extension cord instead of using a transfer switch, that is fine. All you need to do is make up a plug that has the neutral connected to the ground pin, plug that plug into an unused outlet on your generator and your furnace will run fine.

There are many places on the internet that show this and even some YouTube videos that address this problem.

My furnace will not run on my Honda EU2000 unless I bond the neutral to the ground lead.

Actually grounding the generator to a ground rod will make no difference and will not fix your problem.

Do you have the generator manual? Some generators have a provision for adjusting the no load voltage and also the frequency. With a good digital multimeter you should make sure that the voltage is within the range specified on your furnace nameplate, and also that the frequency is 60 hertz.

Another thought, when we ran our furnace on the generator I would start the fan first, on manual, then turn up the thermostat for the burner to kick in.

When we installed a new HVAC unit about 8 years ago I asked about generators since I had heard of this issue. I?ve got a 19kw diesel generator that runs the whole farm, so it?s a fairly stable source of electricity. The installer told me that running the unit on generator power of any kind would void the warranty. Something about it being hard on the variable speed DC blower motor.

I?m not sure how they would know although I guess a burned up blower motor after a snow storm when the whole area had been without power would be a tip off.

Anyway, glad I never used it. About a year ago that fan motor quit. It was $1500 but was covered under some sort of serial number bulletin. Glad it wasn?t on my conscience. Our heat pump furnace only runs as a backup anyway as I heat with wood. That air conditioning is a different story, though!

At work, when we want [u:7ff293db83]really [/u:7ff293db83]clean A/C, we use A/C to power a battery charger, hook that to a big hunk of batteries, then power an inverter from the D/C batteries.

So, go get ten, twelve-volt batteries and wire them to a charger, wire them in series, no, wait, parallel...wait, never mind.

Don't know where you would find an isolation transformer. I would think it would clean up the generator's power.

We have had an issue with the electronics also. MUST have the proper
ground to work even on power company electric.