Goodman Furnace on Generator

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Old 04-06-20, 05:50 AM
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Goodman Furnace on Generator

I have a Goodman 2-stage furnace (GMEC960803BNAB, 80k BTU, 8A) and a Honda Generator (EU 2200i) that I purchased as an emergency power source after several power outages in 2019.

The generator will run everything I plug into it....except the furnace. The furnace will throw fault code 9: ground fault or reversed polarity. I have consulted Honda "technical" service, which was a giant waste of time. My father and I (retired electrical engineer) have been unable to resolve the issue.

Does anyone have any thoughts on what the issue might be?

Thanks!
 
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Old 04-06-20, 06:56 AM
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Over the years I have come up against similar problems where a furnace would work on house power but not emergency generator power. Checking on a generator blog that I would go to often introduced me to "dirty sine waves" and their effects. The site I will attach goes to the matter with less reading and with your electrical backgrounds I hope it helps. BTW, your furnace does have an ECM motor.

https://dam-assets.fluke.com/s3fs-pu...12_ENG_A_W.PDF
 
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Old 04-06-20, 07:17 AM
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Thanks fastback, I will take a look. My generator is an inverter, so I would be surprised if the sine waves were the issue.
 
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Old 04-06-20, 07:58 AM
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Is the ground and neutral bonded in the generator or elsewhere? The furnace uses the chassis ground for the flame sensor. Normally ground and neutral are bonded at the main panel.
 
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Old 04-06-20, 08:08 AM
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Yes, Honda refers to it as a floating neutral. In line between the generator and the furnace I tried bonding the ground and neutral at a receptacle and then taking the generator ground to the house grounding rod - no luck.
 
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Old 04-06-20, 10:25 AM
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If your generator is GFI protected..... then you cannot connect or bond the ground to neutral or the GFI will trip.
 
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Old 04-06-20, 11:57 AM
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The Honda EU2200i is not GFI protected.
 
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Old 04-06-20, 12:24 PM
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I struggled with this during an extended blackout with a water heater. After hours of troubleshooting, I found out the water heater would work IF the furnace wasn't connected. Turns out one of the molded extension cords I was using had a reversed hot/neutral which I never realized and was causing the ground issue.
 
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Old 04-07-20, 04:15 AM
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Thanks Zorfdt, I will try another extension cord just to rule it out. The extension cord has been in use for many years, but will be good to rule it out.
 
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Old 04-07-20, 12:13 PM
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Do you have a multi-meter? If so, with everything turned off measure the resistance between neutral and ground at the furnace. Should be close to zero.
 
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Old 04-08-20, 04:20 AM
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Thanks Astuff, all is well with the wiring.
 
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Old 04-08-20, 04:26 AM
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I decided to email Honda customer service and received a quick response:

From the information you have provided about your EU2200i not operating your Goodman Home Furnace..

Honda has had other customers with similar concerns that their generators will not power their appliances and furnaces.

Our engineers have informed us that the generator is not compatible to power up every piece of equipment. They have seen this occur especially with furnaces and our inverter style generators. The cause is the igniter in the furnace is not compatible with the inverter in the generator and one cannot read the other. Thus the reverse polarity in some cases will be seen.

This does not mean there is a problem with either the furnace or the generator but together they will not operate and are not compatible.


This is, of course, very disappointing. I have no other use for this generator other than for cold weather emergencies/power outages, so I essentially have a $1100 paper weight. Good thing I paid double what the other brands cost just for the Honda reliability.
 
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