heater doesn't always run

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  #1  
Old 12-11-02, 06:53 AM
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heater doesn't always run

My folks (an older couple) are moving to a new home. The new home has 2 furnaces (one for bedrooms and one for living area). Since they have not moved in yet, they are keeping the thermostat low (around 55). The furnace for the living area cycles on-off according to the thermostat. The furnace for the bedrooms does not seem to work properly.

The thermostat is a simple round mercury type and I can clearly see that it is in the "on" position. When I check the furnace, the draft blower (???) is running but the burner is not on nor is the main blower. Sometimes, if you turn down the thermostat and then back up, it will kick on properly. When we were there last weekend, they had the temperature up to 70 and all was well.

It seems like something intermittant. It also seems to reset to a functioning mode if the furnace is turned off and then back on.

Where do I look and what to look for.

Sorry, but I forgot to get the make/model when I was last there but I can if those specifics are needed.
 
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  #2  
Old 12-11-02, 12:13 PM
rclhvac
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Sounds like the furnace is locking out on fault error.
Check for led flashing on main board or on gas valve.
Each manfacture is slightly different M# & S# will help
 
  #3  
Old 12-12-02, 08:10 AM
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more info on model

The make/model is Comfortmaker CGUA100A016 (manuf. 1984).

I don't see any lights or LEDs to check.
 
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Old 12-12-02, 05:42 PM
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that model

probably did not have fault coding as it was a "first generation" at that time high efficiency furnace. the draft inducer motor should run approximately 30 seconds before ignition device (hot surface or spark) then gas valve opens. flame is sensed by sensor, valve held open. if the high limit is opening due to high temp (dirty filter or coil) the inducer would run, but so should the blower.
 
  #5  
Old 12-13-02, 06:06 AM
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soooo....

Sorry, but as a simple DIY homeowner, I am not getting much direction from your reply. Should I be looking at the ignition device, a sensor or something else? How do I check it or should I just replace a suspect part?
 
  #6  
Old 12-13-02, 01:13 PM
george7197
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there may be several things that can be causing your intermintent lock out problom. It can be a high limit switch over heating due to several reasons, plugged coil or filter. flame rollout switch opening due to a bad heat x-changer or bad blower, auxillary limit opening if you have a downflow. Dirty flamerod/ sensor. there can possibly be a short somewhere in the system. It can be 20 different things. Whatever wrong it sound like it's locking out. turning off or the temp. down + up resets the board on the the furnace till the next occurence. My best recomendation to you would be to not waste your time/money changing parts but to call someone who knows what they are doing.
 
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