proper furnace venting


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Old 07-08-13, 07:42 PM
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proper furnace venting

I bought a house and the furnace vent looks rigged. I had trouble with the pilot lite going out this past winter. I climbed on the roof now, and the pipe going into the vent cap is rusted and what looks like a wind break that is wrapped around the venting on the vent cap is rusted and flappin in the breeze. I'm going to replace what is broken or rusted. The furnace is a Hamilton, model gd075-3 rev s . The vent pipe coming out of the furnace is 4". It goes up into the attic does a slight bend then they have put in an adapter to 6", then it does another bend, then out thru the roof. My question is, is this correct ? Should it be all the same size as what is coming out of the furnace ? Should it be double walled ? Cause it's not. How far up from the roof opening should it extend. I have a low pitched roof. Opening in roof is roughly 2 feet from the crown of the roof, no valleys, straight roof. Thank you !
 
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Old 07-08-13, 08:36 PM
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pictures will help. It should be B (double wall) vent. It does not have to stay the same size, but it would be better if it was if there is no other appliance (IE water heater) common vented with the furnace. The vent should extend above the peak of the roof.
 
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Old 07-09-13, 05:00 AM
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I'm wondering if the pilot lite kept going out because they have 6" diameter single wall going thru the roof and the fact that the cap was falling apart ? Is this possible ? If I do decide to make it all one size, 4" which is what comes out of furnace, (no other appliances hooked in with it), how will I fix the roof flashing to go from the 6" hole, to a 4" hole ? No camera, sorry.
 
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Old 07-09-13, 05:33 AM
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A roofer would be required and or a different flashing.
 
 

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