central heat not loghting


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Old 10-15-03, 10:29 PM
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central heat not lighting

Heil split system between 5 and 8 years old. Furnace in the attic. Has no ignition. Fan comes on and blows through the registers when stat turned to on in the heat position, nothing in the auto position. Exhaust fan comes on in the auto position. Suggestions? Tried crossing the red and white wires at the stat. Blower and the exhaust fan comes on ( I think ).

I forgot, the gas is on at the meter. I intend to check the exhast vent tomorrow. While I am at it, should this furnace have a filter of its on along with the one at the return? I clean it once a month. Hoping some cleaning may fix this problem. Wasp in orifice or something like that.
 
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Old 10-16-03, 05:46 AM
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1st off with the red and white jumped the furnace should fire. If the blower and combustion fan is coming on and that's it either the prover switch is not closing or you're not getting ignition "pilot". "Most common" Is this a 90+ furnace with pvc flu pipe or 80% with metal flu pipe?

What type pilot do you have? Hot surface or spark?

Blocked flu would cause the prover not to make.

If the a/c blows through the same ducts as the heat then yes the filter in the return is the right one.
 
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Old 10-16-03, 06:34 AM
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I will get some #'s off this thing and post sometime today. I have worked on many things, central units not being one of them, so I am a little green on this. When I checked the wires at the stat ( red and white), shouldn't I get 24 volts? No voltage there made me think maybe the transformer was bad.

Is this a 90+ furnace with pvc flu pipe or 80% with metal flu pipe? Metal, I think.

What type pilot do you have? Hot surface or spark?

Not sure. Seems like I used to hear a click when it came on. Not a permanent flame, I do know that.

Thanks. I will try to confirm these answers later today.
 
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Old 10-16-03, 11:22 AM
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You should be getting 24v at the T-stat R and W.

When you said your exhaust fan came on, then you are getting power.

When the small fan comes on, the pressure switch should make, then will tell the ignitor to light up the Pilot w/ spark, or HSI (Hot Surface Ignitor) After one of the two lights up, the main burner should take off.


So I would check the venting like Matt said, if all clear, then take your meter and you read 24 volt at the switch, then you swich maybe plugged or vent issue.. Remove the small hose, and blow it itmake sure there nothing in it.
 
 

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