Stupid lennox overhead heater

edwin dirnbeck · Feb 6, 2014

I have a LENNOX 125,000 btu overhead gas heater in my workshop.I only use it on the weekends,the rest of the time I turn it OFF.If it gets colder than about 30 F,the small SAFETY blower that evacuats the flue pipe is wimpy and takes too long to come up to speed and it times out.So I must stand there and restart it 3 or 4 times. Finnally after 3or 4 times I guess the oil in the bearings heats up enough and to motor comes up to speed .Afer the initial cold start the unit works fine.This unit is about 12 years old and it has allways done this .Years ago I put a 60 watt bulb under the motor and it will now work down to 20 F.I dont know why I put up with this this long ,but now I am going to fix it.About 5 years ago THE ELECTRONIC BOARD went out and I bought the new and redesigned board for about 180$.I am afraid to put a a stonger SAFETY BLOWER motor on it because ther might be some thing on the board that might burn up.ANY ADVISE WILL BE APPRECIATED.My old school lennox heater had a pilot light no boards and worked fine for 30 years until a storm knocked the buiding down.Thank you Edwin

jlevie · Feb 6, 2014

If the board controls the motor directly and simply turns the blower on and off, the board can control a relay that will operate a larger motor. You would just have to determine what is being supplied to the motor (voltage and whether it is AC or DC).

Chip Chester · Feb 6, 2014

^^^ is easy, to be sure.
If you have a good supplier available, ask what other, larger units your replacement board is spec'd for, and then pick a replacement fan from one of those larger units. If it's busy at the parts counter, though, just use the relay.

Chip

JRIowa · Feb 6, 2014

Sounds like the evac motor has been bad from the start. That's what I'd replace first. Never seen one that was temp sensitive that much.
JR

eKretz · Feb 6, 2014

Probably sticky. Just like a fan you use to cool you off in the summertime, the bearings (which are often sleeve bearings) collect dirt and gunk in the lube and they get sticky over time and have a hard time spinning up. Cold weather of course makes it even thicker and stickier. Clean that bearing out and relube it or swap to a new blower motor. If it did this from new then get a stronger one.

moonlight machine · Feb 6, 2014

My house had a new Lennox pulse furnace in it when I bought it. The POS has never made it through 1 winter in the 10 I have lived here without a failure of one sort or another. Why don't you leave it on, just turn it back to 40* or so?

edwin dirnbeck · Feb 6, 2014

moonlight machine said:
My house had a new Lennox pulse furnace in it when I bought it. The POS has never made it through 1 winter in the 10 I have lived here without a failure of one sort or another. Why don't you leave it on, just turn it back to 40* or so?

The lowest that the thermostat goes is 50F.I only use the workshop on weekends .Sometime I skip a weekend, so that means that I might be maintining the empty shop at 50 F for 9 days wilst the outside temp is 20F .This is wasteful and I want to avoid this .Edwin

plumberpieco · Feb 6, 2014

If you find that you still have problems after changing the draft inducer I'd look at the safety pressure switch.

Ohio_Ford_Farm · Feb 6, 2014

edwin dirnbeck said:
The lowest that the thermostat goes is 50F.I only use the workshop on weekends .Sometime I skip a weekend, so that means that I might be maintining the empty shop at 50 F for 9 days wilst the outside temp is 20F .This is wasteful and I want to avoid this .Edwin

You might find its cheaper in the long run to not let the temp get so cold. Your heating more then just the air in the shop. you have to heat everything inside. tools, machines, ect. I use to heat just on the weekend. I found it took a couple hours of heating to get everything close to temp. I would spend time waiting for the shop to warm up vs walking in and only having to raise the temp 10 Deg. or so and being pretty much workable inside as soon as I walked in.

edwin dirnbeck · Feb 6, 2014

plumberpieco said:
If you find that you still have problems after changing the draft inducer I'd look at the safety pressure switch.

I am sure it is not the pressure switch.I can hear the motor slooowly trying to start .The colder it is the sloooower it starts. Edwin

paul39 · Feb 6, 2014

edwin dirnbeck said:
I am sure it is not the pressure switch.I can hear the motor slooowly trying to start .The colder it is the sloooower it starts. Edwin

Get a big hair dryer from a junk store and give that motor a warm up before starting. I have picked up any number of box fans and electric heaters with fans off the curb on trash day. With a clean and lube, made them run for years.

I'm also retired and have more time than money. If it were reversed, I'd just buy a new one.

Paul

CalG · Feb 6, 2014

Ohio_Ford_Farm said:
You might find its cheaper in the long run to not let the temp get so cold. Your heating more then just the air in the shop. you have to heat everything inside. tools, machines, ect. I use to heat just on the weekend. I found it took a couple hours of heating to get everything close to temp. I would spend time waiting for the shop to warm up vs walking in and only having to raise the temp 10 Deg. or so and being pretty much workable inside as soon as I walked in.

I have NEVER found it cheaper to maintain an elevated temperature over any period of time.

It's a math thing, BTUs in vs BTUs out. I'm paying for the ones going in, the outgoing BTUs are taken without reimbursement.

How do you do your figures?

jlevie · Feb 6, 2014

The economics don't favor heating for 5 days of the week if you only use the shop on a weekend. But, there are other considerations. If heavy with equipment there is a lot of metal that has to be heated up after soaking down to 20-30F, or below, before it becomes comfortable to work, and that takes time. It doesn't get that cold where I am, but temps in that range aren't unknown. Before I started using some heat in the shop it could take 3-4 hours to bring the shop to workable temperatures from a 20-30F soak. Unless I turned the heat on the night before that was a sizable chunk out of my "play time". I found a simple thermostat that could be set back to 50F and leave there during the week. It takes a lot less time to bring the shop up to 65 and doesn't cost that much. I noticed after doing that that I had less problem with things wanting to rust.

mjk · Feb 6, 2014

wire the fan to allow it to run independant of the board with an external power cord and a dbl through dbl pole switch.
Once it has warmed up throw the switch back to board controlled.

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Stupid lennox overhead heater

edwin dirnbeck

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moonlight machine

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edwin dirnbeck

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edwin dirnbeck

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