Oil Furnace Blowback Fumes in Basement


Old 12-23-07, 05:11 PM
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Oil Furnace Blowback Fumes in Basement

My 1936 oil-fired furnace has a 26' just-off-horizontal vent run around the perimeter of the basement (including a Y joint where the vent from the water heater joins it and a 90 degree corner) before meeting the chimney flue (another 90 degree turn) . It is a 9" galvanized pipe.
The vent also passes through a wall that has a special insulated pipe.
Every time the furnace turns on there is exhaust odor in my basement shop. I'm guessing the fumes aren't moving smoothly around the corners on the long run and this causes the blowback. The furnace is the original. Why it was not placed near the chimeny is a mystery to me.
Are there any effective solutions for stopping the blowback or setting up another vent that has a blower that turns on for a few minutes each time the furnace fires up? There is a one-way intake flap vent. Does the blowback come through there somehow ( I haven't seen it move during furnace fire-up)? I spend a lot of time with a window open to thin the Monoxide fumes but the heat loss is uncomfortable.
Any insights on this greatly appreciated.
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Old 12-25-07, 08:22 AM
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Although my furnace in my previous home was near the chimney, I had slight blowback also. I discovered that soot had built up in my chimney at the joint where the pipe entered. It made what should have been an 8-10 inch opening only 3-4 inches in diameter.
I know this sounds simple but make sure all the piping and the chimney are clear of soot, debris, etc. I would assume even though you have that long length of piping, if clear and clean the fumes should still flow out and up the opening.
I hope you find the problem, soon.
Old 12-25-07, 11:09 AM
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Good Advice

Ofairlane offers a good suggestion. In addition I think having the furnace cleaned, tuned, & generally checked out would be a good idea, especially with it being as old as it is.
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