toast/burning smell coming from idle gas furnace


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Old 03-20-08, 07:29 PM
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toast/burning smell coming from idle gas furnace

Our 20 year old furnace was just diagnosed to be releasing high amounts of CO in our basement, so we turned the heat off and are getting estimates on a new furnace.

Spring is beginning, so we can deal with out the heat, but there is a toast-like burning smell coming out of the heater now. The only thing running is the pilot light. We didn't get this smell at all while the unit was running.

What could be causing this smell? Thanks!
 
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Old 03-20-08, 07:43 PM
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Originally Posted by tedpwatson View Post
Our 20 year old furnace was just diagnosed to be releasing high amounts of CO in our basement, so we turned the heat off and are getting estimates on a new furnace.
Did the tech that condemned your furnace used a digital CO-tester to measure the concentration levels of CO in your basement?

"High amonunts" !!!! Goodness gracious!!!
You would all be dead in that house if that were an accurate statement!
How many PPM was the concentration of CO in your basement, as per that techinician? Did he/she tell you?

If I were in your shoes I'd get at the nearest hardware store a plug-in type CO monitor and see if it beeps.
 
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Old 03-20-08, 07:53 PM
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It was 33ppm. I have CO monitors in the house and they never went off, until i placed one directly on the unit.

Anyway, I was just curious about the smell since the unit isn't running.
 
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Old 03-20-08, 08:06 PM
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OSHA recommends a maximum allowable concentration of 50ppm for a worker's continuous exposure over an "8-hr period"
(this is the organization in charge of protecting workers)

EPA has a stricter standard. 9PPM for an 8-hr period, 35 for a 1-hr period.

It's very unlikely that your furnace will be running non-stop. They cycle, so unless it is firing around-the-clock, you wont see the 33 ppm spewed around the basement, and even less so if you have the proper draft up the chimney.

All furnaces produce some CO as part of their combustion. How much would be normal for your furnace is hard to tell without the specs of the unit. So long you have a negative draft (a draft going up the chimney), you're not in danger. If you have a basement that is airtight, you ARE at risk. But so will you with a new furnace if it draws air from the basement that is airtight. Do you have a finished basement?

Hard to tell what the smell might be. You'll need to get close to the furnace and peek inside, by the pilot and the burners, to see if there's something that fell there. The smell is certainly not normal.
 
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Old 03-21-08, 09:59 AM
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Why not shut off the gas valve to the furnace so the pilot isn't running? This will stop CO2 production.
 
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Old 03-21-08, 10:18 AM
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Originally Posted by tedpwatson View Post
Our 20 year old furnace was just diagnosed to be releasing high amounts of CO in our basement, so we turned the heat off and are getting estimates on a new furnace.

Spring is beginning, so we can deal with out the heat, but there is a toast-like burning smell coming out of the heater now. The only thing running is the pilot light. We didn't get this smell at all while the unit was running.

What could be causing this smell? Thanks!
Seems to me the ticket should spell out the problem. 33ppm could be a dirty pilot. Unless you want a new furnace I would lean toward another opinion or repair. I'm assumig the read was in the flue gas. Not in the room.
 
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Old 03-21-08, 11:39 AM
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Originally Posted by mbk3 View Post
Seems to me the ticket should spell out the problem. 33ppm could be a dirty pilot. Unless you want a new furnace I would lean toward another opinion or repair. I'm assumig the read was in the flue gas. Not in the room.
As much fun as furnace shopping is... I'm going to get a second opinion.

Thanks.
 
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Old 03-21-08, 08:41 PM
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Since the pilot is on, you may be smelling "odorant". The smell of gas is not natural. The smell comes from "odorant" added by the gas company. Sometimes, after very cold temperatures, with a rapid warm-up period the addition of the odorant will be out of regulation. The excess can cause a smell even with a good flue system. Get a second opinion. Most HVAC pros make their living honestly. Some do it the other way.

In Janruary I had this smell in my home from my gas logs. I could also smell it slightly in the basement. When I enquired to the gas company they wanted to come immediatly for an inspection. Since I was at work their solution was to turn off my gas. I convinced them that there was not a leak. I couldn't get them to admit, however, the possibility of excess odorant. A friend of mine who happens to be a former gas company employee told me that this is a common problem in winter. Being retired, he is free to speak.
 
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Old 03-22-08, 06:52 AM
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I was on older nuclear submarines. The original atmosphere control equipment was designed to keep CO below 50 ppm. They found that as it approaches that level, there start to be issues with headaches, and probably the medical effects were determined to be not so nice! So after several years, the equipment was improved to maintain a spec of 25 ppm max. Much mo' better!
 
 

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