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Old 01-18-2007, 12:58 PM   #1
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Freedom 90 furnance not running reliably from generator

I have an American Standard Freedom 90 furnace and we just had an extended power outage and it looks like we have more coming.

I have a 7000w portable (gas) generator that I've used and at first things seemed OK. I was able to run our well pump, hot water heater, a few lights and the furnace without any problem, but then at one point the furnace would not come back on. The status light remained lit (not flashing but steady on), and the burner and fan motor were not on.

I tried different combinations from none to all circuits on and still the furnace wouldn't come up. The odd thing is that when main power was restored the furnace came back on and has been running fine for the past 24 hours.

I'm wondering if anyone can tell me more about that status light (the installer's guide and owner's manual say nothing), and also if anyone might have some thoughts on the problem of running it from the generator.

I've heard different theories about the quality of power from the generator, but I'm not sure if I have any options for conditioning or filtering the power from the generator to try to resolve it, or perhaps if there is some way to bypass the electronics of the furnace and get the burner lit and fan motor running from the generator.

I appreciate any and all thoughts and suggestions!



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Old 01-18-2007, 04:40 PM   #2
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Hi jrielsky

The problem with running a newer furnace off of a generator is dirty voltage. Alot of times you can eleviate this problem by driving a ground rod and grounding the generator. The new furnaces have to have correct polarity all the time to work properly.

Good luck


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Old 01-18-2007, 05:36 PM   #3
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thanks... also may try longer reset

Thanks, will give it a try. Also spoke to a American Standard tech and they claim the latest equipment is very picky on voltage +/- 5% and if its outside of that you'll get a controller error and the furnace won't start.

He also suggested that when attempting to restart it after a controller error that 3-4 minutes is worth waiting to make sure the controller is reset. Not sure how the controller holds its state without power but I'll try anything to increase the odds that the furnace will work and give us heat during an outage.
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Old 01-19-2007, 11:03 PM   #4
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I have also been looking into, as well as posting here in hvac and electrical, using a generator to power our gas furnace during an electrical outage.

Besides learning about safe ways to connect my generator to the furnace, I have also learned about the relationship between the electricity produced by the generator and the electrical requirements of a gas furnace.

Rusty is correct, and I have learned in the past to trust his inputs, that different generators produce different voltage (and voltage types) and that the generator should be properly grounded. In the past I have been running "spaghetti lines" from the generator to each appliance I wish to power up. I also have the generator grounded to the same stiff copper wire that runs from the grounding rod for my service panel and my copper water pipes. Just want to make sure that any stray voltage finds it way back to Earth somehow.

I am also starting to learn more about sine waves produced by the generator along with the rpm's required to maintain a constant voltage output the the gas furnace likes. There is much to left still to learn. Bottom line is that there is more to this than just hooking up the ole gas furnace to the genny and starting it up...a lot more. Sometime we are lucky and the heat comes on or other times the gas furnace goes on tilt or worse yet has a melt down of sorts.

Where I think I am going with all this is that I am considering keeping the generator isolated from the house electrical system and setting up a secondary system in the house that is power only by the generator when needed. Kinda like a seperate panel where the amount of electricity being used is monitored, with a few breakers and lines running to...for example, a single red colored outlet for the fridge, freezer, microwave, a couple lights and a couple places where space heating can be used in a few rooms. Maybe even a few places to use a few other items along with a small television and dvd player. Will have to sit down and do the math to see what my generator can handle safely.

So far, this is where my research is leading me too. Maybe I am over thinking this...but then again, I want to keep my family and others safe too.

Thanks for listening... Casey
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Old 01-21-2007, 06:54 AM   #5
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the furnace id going to be picky because everything has to be just right or the IFC thinks there is a problem and will not allow the furnace to fire. would be best to run a space heater off of your generaor because it will run, if you have an old furnace, you are good to go as its just your typical fan motor and blah blah blah.
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Old 01-21-2007, 09:36 PM   #6
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most water heaters have from 4500 to 5000 watt elements if your well pump was to start at the same time as the water heater was on you would more than likely overload the gen set. try turning off the power to the pump. furnace and water heater then power the furnace back up and see what happens.
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Old 02-12-2008, 01:48 PM   #7
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I have a Lennox furnace that is 5 years old and I went through something very similar during a recent power outage. What I found out is it has nothing to do with the ground. My house was rewired 3 years ago and I kept the panel ground hooked up, grounded the generator to the same ground wire outside that came off the panel and the furnace would not fire. Unless you have a higher end generator with a built in conditioner it will not run some of these new style furnaces. I am going to wire up an electrical outlet off of my transfer switch and set a 15 amp line conditioner in line and wire another electrical outlet to the side of my furnace in line with the on off switch and plug and extension cord to the line conditioner in the next outage. If you have a good enough quality conditioner that will regulate the voltage iregularity and the poor wave sign off the generator. Every furnace is different so it all depends on the tolerance of the electronics in the unit you have. Unfortunatley, after talking to tech support, I found out that mine has virtually no tolerance so I am stuck.



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