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Old 01-04-2012, 01:11 AM   #1
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Unburned Gas Smell.


Hey Everyone, I have a ComfortMaker RPJ forced air furnace. About 1 month ago we woke up to cold air and nothing else. I opened her up and did some trouble shooting with the help of this site and found out my ignitor was no good. It really wasn't. It was cracked and when I took it out the wiring fell off. No problem, I went down to our local hardware store and purchased another one. The one I had was a ceramic coated one and the one I purchased is more of a metal wand. I installed it and while I had the burner box openend I went ahead and cleaned out a bunch of charred pieces that were sitting in the bottom of the each of the burner bays. After that the furnace starts right up and heats up. The problem is the smell. When the furnace first starts up and the air starts to blow I get this very strange smell, at first I thought it was unburned gas but it actually smells alot like the the char/soot that I cleaned out. It only smells like that for the first 30 seconds, as soon as the hot air starts to come out the smell goes away. I have taken everything apart and re-cleaned everything. New filters. We have carbon monoxide detectors in the house and the garage and they are not sensing anything so I don't think we have a leak. I also checked for leaks with a water /soap solution. Is this normal for a new ignitor? could I have purchased the wrong ignitor and therefor its not getting hot enough to light up right away? Everything seems to be working great except for the weird smell at start up. Any ideas?

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Old 01-04-2012, 05:34 AM   #2
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Unburned Gas Smell.


Something is not right. Could be you have a small crack in the heat exchanger. CO detectors don't go off at low levels.

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Old 01-04-2012, 06:16 AM   #3
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Unburned Gas Smell.


could be a getting larger crack in the heat exchanger or popped rivets which hold it together. those exchangers have quite a few failures like that.
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Old 01-04-2012, 10:04 AM   #4
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Unburned Gas Smell.


After reading a few of the posts here that was kind of the conclusion I was coming to also. By why did this start after I switched the ignitor? Did it have something to do with the fact that the heater was on all night with no flame? Also I have never had an HVAC guy out to our place any thoughts on average rate to have them come out and confirm that the exchange is cracked?
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Old 01-04-2012, 10:30 AM   #5
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Unburned Gas Smell.


Quote:
Originally Posted by cessna1466u View Post
Also I have never had an HVAC guy out to our place any thoughts on average rate to have them come out and confirm that the exchange is cracked?
Figure on a couple hundred VERY WELL SPENT dollars.
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Old 01-04-2012, 10:40 AM   #6
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Unburned Gas Smell.


Really. A couple hundred to come out and sniff and inspect, or to change the heat echanger? What are my concerns if it is not repaired right away.
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Old 01-04-2012, 10:48 AM   #7
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Unburned Gas Smell.


Carbon monoxide ,sickness or death.
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Old 01-04-2012, 10:50 AM   #8
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Unburned Gas Smell.


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Carbon monoxide ,sickness or death.
Oh, just that? Thanks alot guys for all the great replies. I really appreciate the help. Any thoughts thought on why I only smell it when it starts and not all the time. I would think if there was a hole in the exchanger the smell would be there all the time.
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Old 01-04-2012, 10:57 AM   #9
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Unburned Gas Smell.


The visit itself and the diagnosis will probably run you less than $100, the actual figure a function of who you call and where you live.

I'm in no position to give you an estimate on the cost of repair.

On another note, you might ask them to check while they are there and see if you put in the right igniter. I used to have to change the ceramic one on my old Carrier in our old house damn near once a year, like clockwork, in the fall and I always bought an exact replacement. If what you put in looks markedly different than what you took out there is a fair to middling chance that you bought the wrong part, IMHO.

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Old 01-04-2012, 11:03 AM   #10
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Unburned Gas Smell.


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On another note, you might ask them to check while they are there and see if you put in the right igniter. I used to have to change the ceramic one on my old Carrier in our old house damn near once a year, like clockwork, in the fall and I always bought an exact replacement. If what you put in looks markedly different than what you took out there is a fair to middling chance that you bought the wrong part, IMHO.
Thanks, this was my initial thought. Im sorry about all the questions, I just like knowing the answer as to why something is broken. If I installed the wrong ignitor what would that cause? Does it take to long to heat up enough and that leaves unburned gas in the chamber that ignites as soon as the ignitor is hot enough, thus sending out that awful smell? But if that is the case, isnt the chamber with the flames sealed and that smell should be getting into the air stream. I stand there and smell the sorroundings of the blower motor and furnace and don't smell the smell its only inside the house throught he vents.
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Old 01-04-2012, 07:26 PM   #11
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Unburned Gas Smell.


I have had some of them split VERY bad with large cracks and open up from several popped rivets. It gets worse and when they open up the fan pressurizes the chamber/ht exchanger and you get flames rolling out the front and tripping the rollout switch. By then it is unsafe to use. They have had a history of both of those problems. In their defence the new ones use a steel rivet instead of copper and hopefully the metal is better. The fumes/CO and smell can get into the house thru the cracks B4 the fan starts. May just be a co-incidence that it has gotten worse now and the igniter failed at this time which has nothing at all to do with the heat exchanger.
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Last edited by yuri; 01-04-2012 at 07:29 PM.
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Old 01-04-2012, 08:03 PM   #12
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Unburned Gas Smell.


Sounds like the wrong ignitor, should be open ceramic ignitor for that furnace. Can't see how all of a sudden the h/xchanger would be cracked. Check the burners when the main fan is on see if they are rolling out or really wavering around. Both sure indications that the heat exchanger is comprimised.
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Old 01-04-2012, 08:28 PM   #13
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Unburned Gas Smell.


Every, and I mean every,furnace heat exchanger I found sooted up had a big ol crack in it. Soot also takes the CO level in the flue gas from a few parts per million to a few thousand parts per million. Get it inspected ASAP. It doesn't cost that much and if a new furnace is required,and purchased from us, we wave the call/inspection fee. Many companies will have the same policy.

As for the ignitor the nitride upgrade you installed is fine. It didn't hurt the heat exchanger or cause the soot but those things might have caused the old ignitor to fail.
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Old 01-04-2012, 08:38 PM   #14
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Unburned Gas Smell.


cessna due yourself and your family a loving gesture get the unit serviced and have that exchanger checked....well worth it...
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Old 01-04-2012, 09:04 PM   #15
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Unburned Gas Smell.


"Every, and I mean every,furnace heat exchanger I found sooted up had a big ol crack in it."
Not true, check the older Bryant/Carrier furnaces the air adjustment on the burners is screwed right through the burner a natural trap for any lint etc... have seen plenty of furnaces plugged with soot because they are starved for air. Piece of crap design on the burners, but keeps us in business. LOL

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