Help! Furnace keeps turning off - we're getting cold


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Old 01-06-05, 04:47 PM
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Help! Furnace keeps turning off - we're getting cold

Nightime temps (outside) have been getting down in the teens. I have the thermostat set to 68 degees at night. Every morning when I get up, it's usually between 62 and 64 degees in the house. I turn the switch on the thermostat off and then on again and the furnace kicks on. It runs for awhile and blows warm air into the house but then it shuts off. I have to go flip the switch again to get it to run again, which it will for a short time and turns off again. It runs maybe 15 or 20 minutes at a time and the temp may rise 1 or 2 degrees before shutting off again. I'm constantly flipping the switch and it seems I can never get the house heated up. I have been told it might be a high limit switch? Or, it could be a flame sensor??? The furnace is only a year and a half old - it's made by Armstrong. Any help or advice would be so appreciated. Money is tight.
 
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Old 01-06-05, 07:38 PM
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Check your Warranty papers, You may still be covred. if so, call the installing dealer to take care of the problem.

Something is locking out on your, and you may hve some flashing light on the control board telling you what's wrong.
 
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Old 01-06-05, 09:23 PM
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the warranty is 1 year parts & labor and 5 years parts - the company that installed it is apparently out of business. We called another place and they said they would order a high limit switch (?) for us. All other places said they would have to come out and look at it and we'd have to pay them to come out. They said if it's under warranty we wouldn't have to pay for the parts but still for the labor. My dad came over and looked at the blinking lights and said it indicated it was overheating and shutting itself off and that it could be a faulty switch, if that makes sense. Last winter we didn't have any problems and up until it got reallly cold it was working fine. It is definitely something that has to do with the colder temps. We first thought it might be the thermostat and so we purchased a new one and installed it but that didn't make any difference.
Are there any adjustments on the furnace that could help? Should we just order the high limit switch and see if that fixes the problem? I'm wondering what else it could be. We just put in new filters in December.
 
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Old 01-08-05, 04:31 PM
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I think you should make sure the air filter is clean and is the correct one. Not one of those charcoal ones that restrict flow. I would have suspected flame sensor before high limit but you have to rely on the flash code. If the house is cold, there is no reason that the furnace should get to high limit that quickly if there is sufficient airflow.

Ken
 
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Old 01-09-05, 05:00 PM
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Some times the error code is 4 flashes which indicates the rollout or limit switch is open (which causes the furnace to shut off). Other times the error code alternates between 4 flashes and 6 flashes which indicates that the lockout is due to the limit switch. We have put in new filters, even tried running it with no filters. We also bought a new limit switch and put that in and that didn't help at all. My husband went under the house and in the attic and checked all the duct work to make sure there are no problems there and he found nothing wrong. We are at a loss. Apparently something is causing the system to overheat which causes the limit switch to open and shut off the furnace. After some times passes, it starts up again and runs for awhile and then shuts off again. It never heats the house up to the set temperature. During the night it does a miserable job and I'm lucky if it's 64 when I get up. It's supposed to get cold here next week (around zero, or maybe even below) and I'm worried. Does anyone have any suggestions on what else could be causing it to overheat and open the limit switch???? Any ideas or help?
 
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Old 01-09-05, 05:23 PM
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Is there a strong airflow from the ducts? It sounds like a system would act if the blower motor was operating in reverse. The flow must be that poor to overheat the heat exchanger. Did it work well prior to this problem? If so, what could have changed since it worked properly?

Ken
 
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Old 01-09-05, 06:07 PM
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The airflow is average I guess. We have lived here a year and a half and the furnace was new when we moved in. It worked fine last winter. I wouldn't say that the airflow is really strong, but it is adequate. Absolutely nothing has changed since last winter. That's really part of what is so baffling about the whole thing.
When the gas shuts off, the blower also eventually shuts off (i.e. it doesn't keep blowing). Don't know if that helps in trying to figure out what's wrong.
 
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Old 01-09-05, 06:52 PM
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Check to make sure your returns are not blocked with dresser, desk or some thing.

Just for a test, remove the blower door, and tape the safty switch down.. Turn on the system and see if it's works fine the whole time.

Air should be sucking into the blower area.

Is the A/C as new as the furnace or older? The A-Coil for the A/C maybe plugged up if it's old.
 
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Old 01-09-05, 08:26 PM
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okay, we went out and taped down the switch thing so it would blow with the cover/door off and I think we *may* have (hopefully) figured out what the problem is! There is kind of like insulation stuff that's about a half inch thick that lines the inside of the compartment all the way around. It appears as though it was all glued on at one time, as there is sticky residue all over the metal. However, it is all loose now on the sides (the back piece is still well adhered) and when the blower started up it acted like a vacuum and sucked these two pieces of insulation right onto the sides of it! It seems like this would *severely* limit the airflow! So, we pulled out the side pieces (they were all covered with dirt and dust, too) and we are now running the furnace without them - so far it seems to be working. If this solves the problem, I guess we will vacuum off the pieces and put them back in with lots of adhesive (anyone know if there is a special type of glue we should use?).
I am so hopeful that this was the problem and that it will now work. Thank you so much for your help, Jay! We were getting so frustrated - a furnace this new just shouldn't malfunction like this (6 months after the labor warranty ran out...). I'll keep you updated. Thanks again!
 
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Old 01-10-05, 07:36 AM
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The true test - was the house warm this morning when I woke up? Yes, it was! Thank you so much, Jay and Ken, for all your suggestions. We are warm once again, and just in time for the cold spell that's on its way.
 
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Old 01-10-05, 07:57 AM
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Unless the furnace is located in an unheated space, I would leave the insulation off. I do believe that you found the problem and it could have been a tough one considering the door switch issue. If you need to replace the insulation, you should look for some good spray adhesive and coat both pieces well and reapply them.

Ken
 
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Old 01-10-05, 08:27 AM
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The furnace is in the garage.
 
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Old 01-10-05, 09:08 AM
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There is not much heat to be wasted from that area of the furnace. The supply ducts are much warmer and would cause more losses if they were not insulated. You can be the judge but it is much more important to have the furnace work consistently well, than to have the insulation cause you problems.

Ken
 
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Old 01-10-05, 11:24 AM
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Wink

You can get the fiberglass duct board used for duct and cut and fit this to the out side of the return and plenum out there in the garage.


ED
 
 

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