New furnace puts out a strange smell


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Old 12-13-10, 03:36 PM
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Question New furnace puts out a strange smell

We had our furnace replaced with a new high efficiency one. When the blower comes on we get a blast of Arctic air from outside. (It draws it's air supply from outside and exhausts outside too.) After the heat runs for a few minutes there is a faint oder of some kind, sort of like gas, but no rotten egg smell.
The heating and air conditioner guy was just here. He says he doesn't smell anything. Then he said that sometimes the heat exchangers are soaked in oil before installation. That possible it was that burning off that we smell. The heat has been running for over 2 months, if it was the heat exchanger wouldn't that have burned off by now??
The smell has a faint gas oder. Technician checked all the pipe connections and no gas leaks.
This is a Goodman; model GMH950703BX This is probably a dumb question, but can the the exhaust get sucked back in???
 
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Old 12-14-10, 02:21 PM
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You are a little confused.....the air from outside goes directly into the combustion chamber....so you really cant get an artic blast of air from outside.It is true that the heat exchangers can smell when first starting up,not likely to smell after 2 months with the furnace running. not likely that the exhaust is getting "sucked back in?"
 
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Old 12-14-10, 03:48 PM
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I presume you have two PVC pipes going outdoors, one sucking in fresh air to burn and the other venting the burned gasses out.

If those pipes are improperly installed, you can have combustion gasses sucked back in, but they wont have oxygen for the gas to burn. That can cause soot, carbon monoxide and other off odors called aldehydes.

You should check the combustion gasses being vented outdoors. Do they contain the odors you are noticing? Is there any evidence of black soot in the pipe venting out the combustion gasses?

Did the contractor use a gas detector to inspect for leaks or soap out the fittings?
 
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Old 12-14-10, 05:59 PM
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I don't know where the air goes when it comes in; but I can sure as hell tell you what comes out of the heat vents when the furnace kicks on. If I'm sitting and working at my computer, it's enough to make me get up and move. Tech said all of the "New" furnaces do that.

As to the vent pipes. Yes, they are PVC. They have a box sort thing over them. Keeps thee critters from getting in there. I can probably stick a finger up there and get it inside of the exhaust pipe. Yeah we checked all of the pipes right from the meter all the way to the furnace. No leaks.
The box over the intake and exhaust is factory approved. In fact it came with the furnace.
I didn't hire some handy man out of work to install this thing. It was install by a very reputable company. The smell is not all the time. In fact I didn't smell it at all today. That's why I didn't buy into the theory that it was the heat exchanger burning off oil or paint.
 
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Old 12-14-10, 06:18 PM
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Ummmm. By the way ---- is this odor a kerosene like smell?


Freshly painted walls and other things can release chemicals into the air which cause odd odors when drawn into the burners as combustion air or drawn past the hot heat exchanger.

Is anything like that a possibility?


And what means did the repairman use to check for gas leaks?
 
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Old 12-15-10, 07:11 AM
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"but I can sure as hell tell you what comes out of the heat vents when the furnace kicks on. If I'm sitting and working at my computer, it's enough to make me get up and move. Tech said all of the "New" furnaces do that."
I don't think you should expect hot air to immediately come out of your supply vents when it first kicks on; all the air in the ductwork and the ductwork itself need to be heated until you will feel warm air.
 
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Old 12-15-10, 07:53 AM
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A new furnace will indeed put a smell as it burns off the preservative oil sprayed on at the factory...for maybe 30 minutes.

I'm thinking you have a dead animal in your ductwork. Do you have any flexible ducts? In a crawlspace? Have you inspected the ductwork to be certain there are no holes where a mouse or something could have entered?
 
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Old 12-15-10, 03:12 PM
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No nothing dead. I know that smell too. Had a mouse get into the old intake pipe. Don't know how he got up that high When they pulled the old furnace out I mopped the spot with bleach, then washed that down, with some soapy water. I sucked that up with my wet vac.

When it came time to do the vents, I did them myself. I have a wood shop in the basement and I used the suction hose from my dust collector. It's 10 X the suction you would get from a shopvac with a 2" hose. I made sure all vent pipe are clean inside and out. Even dust on the top of the vent pipe can cause a certain smell. My dust collection system is a little on the overkill side but I don't like breathing sawdust.

The Tech may have done something I didn't see him doing because I haven't had the smell since. I went over into my shop to get a spot light, he may have done some adjustments I didn't see him do.

If the smell comes back, I'll post again but until then, I'm hoping the problem is solved.

That blast of cold air doesn't happen anymore either.
 
 

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