Very tough problem

[Albert Detorre]

My parents have been having a problem with their furnace. The furnace seems to run fine most of the time. However, on random occassions, the furnace begins to start up and get ready but it doesn't ignite and let out heat. So my parents flip the switch off and on to restart the furnace, then it ussually starts up and lets out the heat. This ussually happens at night at least two times a day.

They have called numerous HVAC experts and the gas company to look at the problem and no one has been able to fix it. All the repair people seem to be baffled. The electronic ignition, hot surface module, and thermostat have all been replaced. The gas company has checked to make sure there is no leak. The burners have also been cleaned to make sure no dirt is blocking the furnace from igniting.

The model of the furnace is a ComfortMaker. It is about 20 years old. If you have any recommendations, please let me know. They are considering buying a new furnace and have spent 500 bucks so far in repairs.

Thanks very much for your opinions!
Al

[jking2]

I recently had a similar problem with my Carrier furnace. It would go through the purge cycle and the hot surface igniter would glow. Then the gas would come on for about half a second before everything shut down. The problem was solved by replacing the thermostat. Apparently the defective thermostat was drawing too much current, so the control circuit became overloaded when the gas valve kicked in.

Jim King

[David P. Valley]

http://www.nachi.org/forum/f20/furnace-kicking-13163/

[Charley L. Bottger]

Originally Posted by jking2

I recently had a similar problem with my Carrier furnace. It would go through the purge cycle and the hot surface igniter would glow. Then the gas would come on for about half a second before everything shut down. The problem was solved by replacing the thermostat. Apparently the defective thermostat was drawing too much current, so the control circuit became overloaded when the gas valve kicked in.

Jim King

Jim I might agree that you had a thermostat problem but thermostats do not in most cases draw current they are simply a switch in one leg of the power unless it is a set back stat then it would have a load.

Any time a furnace cycles off on start up or shortly after you can bet your life that a operating or safety device is the reason someone just needs to have the knowledge to find which one is the guilty party. There are to many part changers in the HVAC field and not enough troubleshooters

[jkormos]

Well if it is 20 years old, $500.00 so far to fix, and if the other recomended fixes do not fix anything I would think about getting a new one at this point, why keep throwingmore $$ at it. Also see if the company that did the work will give you some kind of credit on a new system for consideration for the work done that didn't fix the problem.

[Charley L. Bottger]

Originally Posted by jkormos

Well if it is 20 years old, $500.00 so far to fix, and if the other recomended fixes do not fix anything I would think about getting a new one at this point, why keep throwingmore $$ at it. Also see if the company that did the work will give you some kind of credit on a new system for consideration for the work done that didn't fix the problem.

Joe; I guess I don't think like other folks when I pay someone to repair something and its not repaired I will call them every hour until they get sick of me and remind them that I have already paid them once and the same problem exists. Either give my money back or repair the problem. Oh Joe the word FIX is what we country folks do to cats and dogs!!!!! I like the word repair.
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[bbenjamin]

It sounds like from what I have read that your t-stat or your furnance could be wired incorrectly or your t-stat is not programed correctly for your furnace. Since the ignition has been changed that is ruled out, but I would start with the t-stat.

[David A. Andersen]

Don't pay if it's not fixed.

If there is too much voltage drop, an HVAC tech SHOULD have the tools and knowhow to determine this.

As Charlie posted, your getting close to a good down payment for a new unit with that repair bill.