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Old 01-21-2011, 10:31 PM   #1
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Lennox furnace misbehaving


OK.... kindof an emergency situation...

I have a high-efficiency Lennox AC/Heat pump and furnace (furnace is ECB31 with a variable speed handler)... The unit was not meant to cure all my heating needs, but since I am currently working on in-floor radiant heat setup, it has to suffice. It was installed about a year ago.
It has been running all winter without any problem. Yesterday we had a REALLY cold day with a low of about 4 degrees (I am in the midwest). I noticed this morning when I woke up it was colder than usual... It's usually 68 in the AM, but it was only 60 or so. I figured the furnace had met its match and just couldn't put out enough heat, since it was running all night.
I get home from work today, and it's 55 in the house. The furnace is going non-stop. The air coming out of the vents is cool (not cold or warm). It's also warmed up to 17 or so outside, which is not really much colder than it's been the past few weeks, and its certainly been colder with the furnace providing adequate heat.
I tripped the breakers to try to reset the system. I let it cool down for 30 min and then restarted. Nothing seemed to help. The furnace breakers did not trip.

Is there anything I can do short of calling a repairman in the middle of the night or sleep in a ski outfit?

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Old 01-21-2011, 10:59 PM   #2
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Lennox furnace misbehaving


Have you checked the air filters and fan speed?
Is the blower wheel clean?

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Old 01-21-2011, 11:02 PM   #3
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Lennox furnace misbehaving


Check to see if the limits have tripped on the back up electric heater.
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Old 01-21-2011, 11:22 PM   #4
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Quote:
Originally Posted by Artco View Post
Check to see if the limits have tripped on the back up electric heater.

checking all of the above.... Limits.. you mean for the furnace over the heat pump? That happens at 30 degrees...
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Old 01-21-2011, 11:39 PM   #5
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Lennox furnace misbehaving


Quote:
Originally Posted by Artco View Post
Have you checked the air filters and fan speed?
Is the blower wheel clean?

Everything is clean. I know there are those funny-looking connectors that attach to the coils that can break... There are three of them... they look to be in good shape...
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Old 01-22-2011, 08:08 AM   #6
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Lennox furnace misbehaving


The only way to check is getting your hands in there with live circuits and testing componets with a meter. Not a task the average home owner wants to try since 240 volts fused at 60 amps will hurt you bad.
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Old 01-22-2011, 09:47 AM   #7
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Lennox furnace misbehaving


Now you need a professional who can check to see if the heating elements are not broke or loose.
Like Marty says the electric supply is high voltage and can kill!!!

If your thermostat has a switch and says emergency heat, put the switch in that position and see if the heat comes on.
Heat pumps are NG below 30 degrees outside temp.
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Old 01-22-2011, 12:56 PM   #8
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Quote:
Originally Posted by Artco View Post
Now you need a professional who can check to see if the heating elements are not broke or loose.
Like Marty says the electric supply is high voltage and can kill!!!

If your thermostat has a switch and says emergency heat, put the switch in that position and see if the heat comes on.
Heat pumps are NG below 30 degrees outside temp.

Yeah... thanks everyone. I thought about testing the elements, but I have to stick my hands past lots of live wires... I did it quickly to see if I could feel any heat... then my senses got the better of me. I called the installer this AM, and he will come out as soon as he can. The temp in the house is now down to 48 degrees upstairs and 38 downstairs (!!).
I did try to set the emergency heat last night- it is the same as the auxillary heat, I believe, although I have both settings on my thermostat. Bottom line is that nothing different happened. I shut down the system and went to bed. Luckily I have a heated mattress pad. I slept great, actually.
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Old 01-22-2011, 11:50 PM   #9
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Lennox furnace misbehaving


update:

I had my A/C guy come out and try to fix it. Looks like only one of the three heating elements is getting current with a call for auxillary heat. All three have voltage across them. He could not figure it out after 2-3 hrs of playing with it, and said it would have to wait until Monday, when the Lennox service people will be available. There is a delay going from the first to all elements kicking in for efficiency issues, but it seems like the latter 2 just don't ever turn on.

The air handler is the CBX32mv-036 and the furnace heating part is the ECB-29... Does ANYONE know what the problem could be? Looks like it's going to be a cold weekend after all...
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Old 01-23-2011, 07:30 AM   #10
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Lennox furnace misbehaving


That board needs to be configured so it knows how many heat banks to operate. The instructions on how to do that are in your installation manual. I might have a set in the van, will look once it's light out.

Did your guy have 120V or 240V going to the elements? If 240 then the elements are burnt out. If 120 then it's probably a configuration issue.

Last edited by Marty S.; 01-23-2011 at 07:36 AM.
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Old 01-23-2011, 08:52 AM   #11
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Lennox furnace misbehaving


Quote:
Originally Posted by Marty S. View Post
That board needs to be configured so it knows how many heat banks to operate. The instructions on how to do that are in your installation manual. I might have a set in the van, will look once it's light out.

Did your guy have 120V or 240V going to the elements? If 240 then the elements are burnt out. If 120 then it's probably a configuration issue.

I will call him and find out- I didn't see the volt readings.
By configuring the board, you mean the low-voltage wiring, right? Not that circuit board with 4 jumpers on it...

Thanks!!!!
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Old 01-23-2011, 09:17 AM   #12
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I might be thinking of the wrong unit and don't have a manual at home. Pictures would be helpful.
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Old 01-23-2011, 10:07 AM   #13
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Do you have Davenet access? If not I do and can get stuff for you. Blower is 1st elec ht section 2nd
http://tech.lennoxintl.com/PDFs/0206f.pdf

http://tech.lennoxintl.com/PDFs/9727a.pdf
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Last edited by yuri; 01-23-2011 at 10:10 AM.
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Old 01-23-2011, 10:47 AM   #14
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Lennox furnace misbehaving


Update....
I spent some time reading the installation manual.... I have a 2-stage thermostat (which I imply to mean 2 heat types- 1.heat pump and 2. electric). The manual states that if you have a 2-stage thermostat, then a jumper between W2 and R should be pulled, and the 2nd stage heat lead should go into W2. I opened the furnace and saw that the electric heat was wired to W1, and the jumper was still in place. So basically it was wired like a 1-stage thermostat. I changed the wiring... could this have been the problem? I don't feel comfortable checking the vols and amps with the power on....
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Old 01-23-2011, 11:04 AM   #15
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Wait for Marty or one of the other Pros, I don't do heat pumps and attic airhandlers but he knows a lot about them.

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