The camper is 5 weeks old. Atwood model 7916-II furnace. I have run this furnace everyday for 5 weeks.There is a still burning smell that needs to be diagnosed.At day 10 I talked to Atwood service tech and he said of course the oil on the heat exchangers is burnt off. He said maybe there is an overburn condition which would point to a bad regulator on the furnace.So I bought a digital manometer to measure the water column. The water column is right at 10.5 inches which is what the Atwood tech said would be correct.They have no more ideas and suggest taking it to a dealer which is a fine idea. The dealer I bought it from is not being nice and I'm not going to put the story out to the public. I will take it into another dealer but they won't be able to look at it for about 4 weeks.The service people at Atwood don't really have any more ideas of what it could be or they won't tell me. The furnace has been apart and there are no foreign bodies in there. There is nothing in the cavity where it is installed that is touching the furnace and melting. The smell will occur when the furnace is sitting outside the cavity where it was installed.I have gone through multiple tanks of propane from different places so that rules out bad propane.What else could cause a smell that I can check?Thanks.

How was that 10.5" WC measured?Just with furnace running.......or did you have other gas appliances on also (stove top burners on high, water heater on...firing).WC should be measured with at minimum of 50% demand on regulator.Operating everyday for 5 weeks should have most definitely burnt off any mfg. oil residue and/or debris. Have you checked the burner orifice size........should be a #56 (lower numbered orifice would allow higher gas flow)

I did not measure with a demand on other appliances. If I check the burner orifice size, if it is located inside, will likely void the warranty. Atwood said if I take apart the furnace or change anything with it then the warranty will be void. Thank you for the information.

I would be curious as to exactly what type of smell your having. It could be a cracked heat exchanger? You would be getting a high concentration of carbon monoxide if that's the case. This shouldn't be very hard to diagnos. I am a retired HVAC business owner and have worked on several furnaces of this type. The basic design hasn't changed for several years. They are very simple. If I was the dealer I would just replace the unit and deal with the manufacturer myself, if that's what it would take to keep the customer. Good luck

It could be a cracked heat exchanger?X2... I'm also an HVAC man and this was my first thought when I read this. Vic

I do have my own store bought carbon monoxide detector plugged into the AC outlet. The alarm has not gone off and I just checked the peak reading in the unit's memory and it is zero. Thank you very much for the ideas and please keep them coming. I really appreciate it gentlemen.

Furnace help needed | Good Sam Community

kayco53
Explorer
Nov 05, 2013
If I remember right don't home type co testers start measuring at 60pm.
Checked our furnace with the type we use for confined space entry way more $$$ and more sensitive.Are you maybe getting a burned dust smell?
Our old Prowler had a unducted furnace.And that would happen on start up.If I was unsure I would not be sleeping in there with the furnace on.
jefffoxsr
Explorer
Nov 05, 2013
This furnace is a non ducted unit. It just has a direct output. I don't have a meter to measure the CFM but the output is quite strong.
Thank you very much.
Victory402
Explorer
Nov 05, 2013
Is the air speed coming out of the vents proper? If it's too slow it could cause the area around your heat exchanger baffle tube to over heat, thus causing anything (plastic, cabinetry) near by to over heat. A lot of furnace fan motors are capable of 2 speeds (high and low). The manufacturer of the motor does this to save money, thus one motor can work for two different furnaces. It's possible that your fan motor got wired to the lower speed instead of the higher one?? Make sure you have good air flow on the input side and output side. Clogged filter? To many output vents closed off? It would be nice to know the proper cfm
jefffoxsr
Explorer
Nov 05, 2013
I put the CO2 detector right in front of the register and ran the furnace for a while and there was NO CO2.

The air coming out of the furnace has had a strong burning smell for almost 6 weeks. Any more ideas?
Victory402
Explorer
Nov 04, 2013
Plug the detector into an extension cord and place it directly in front of the units output vent. To test the detector is easy, put it behind your exhaust pipe on your car in the same way.
jefffoxsr
Explorer
Nov 04, 2013
I do have my own store bought carbon monoxide detector plugged into the AC outlet. The alarm has not gone off and I just checked the peak reading in the unit's memory and it is zero.
Thank you very much for the ideas and please keep them coming. I really appreciate it gentlemen.
Victory402
Explorer
Nov 04, 2013
It could be a cracked heat exchanger?

X2... I'm also an HVAC man and this was my first thought when I read this.

Vic
bphusmc
Explorer
Nov 04, 2013
I would be curious as to exactly what type of smell your having. It could be a cracked heat exchanger? You would be getting a high concentration of carbon monoxide if that's the case. This shouldn't be very hard to diagnos. I am a retired HVAC business owner and have worked on several furnaces of this type. The basic design hasn't changed for several years. They are very simple. If I was the dealer I would just replace the unit and deal with the manufacturer myself, if that's what it would take to keep the customer. Good luck
jefffoxsr
Explorer
Nov 04, 2013
I did not measure with a demand on other appliances. If I check the burner orifice size, if it is located inside, will likely void the warranty. Atwood said if I take apart the furnace or change anything with it then the warranty will be void. Thank you for the information.
Old-Biscuit
Explorer III
Nov 04, 2013
How was that 10.5" WC measured?
Just with furnace running.......or did you have other gas appliances on also (stove top burners on high, water heater on...firing).
WC should be measured with at minimum of 50% demand on regulator.

Operating everyday for 5 weeks should have most definitely burnt off any mfg. oil residue and/or debris.

Have you checked the burner orifice size........should be a #56 (lower numbered orifice would allow higher gas flow)

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