Furnace change (problem?)

[ky-newbie]

Hi all,

I have a 2008 Keystone Springdale 249 FW, and the furnace operation has suddenly changed. It has a Duo-Therm thermostat which is turning the furnace off/on with no issues. The FW hasn't been moved since Sunday, and until yesterday, it seemed to work fine. I've been running the furnace for several weeks, as needed. I did refill a propane tank Saturday.

Here are the change details:

Today, I am getting a smell inside the FW that smells like exhaust. I've checked the outside ports, and they're clear. I can feel the exhaust coming out, with just as much volume as before. There is no wind to speak of.

The temperature coming out of the floor vents has dramatically increased. Previously, I could hold my hand over the vents without any problem. I just measured the air with a laser device, and it's 114 degrees. Holding my hand there for more than a few seconds is not possible.

Any ideas?

Thanks!

[time2roll]

My 2006 249 has an issue of not enough airflow and cycles the burner against the high limit switch. I am thinking yours could be similar except the limit switch has failed in the closed position causing excess temperature.

I thought for sure the tech would have tested the switch but you did not say.

I have recently added an additional vent for more warm airflow to the interior but have not been out yet to really test it.

[TXiceman]

Stop using the furnace until you can get ti checked. You can get a CO check kit from a number of places. leaving the doors and windows open, fire up the furnace and check for CO at the registers.

And as noted, an infra-red temperature sensor will not measure the air temperature.

Ken

[Paw_Paw_John]

Just thinking that you coul check into the Cheap Heat System and attach it to your gas unit. This will convert it to an electrical unit also. It's going on four years now that I have installed one in my 36 foot Mobile Suite, 2004 model. I love this upgrade and keep my camper plugged in all winter and the heater is set on 50 degrees all winter. This is the best upgrade I installed in my camper ever!!! PM me if you like to ask any question about this system. You can check it out at rvcomfortsystems.com, Good luck.

[Old-Biscuit]

Still suspicious........

Wasp nest 'could' block exhaust enough to increase heat transfer so that room air temp increased BUT.....
Increase room air temp enough that you couldn't hold your hand over register?
Block exhaust enough to cause an increase in heat transfer and NOT cause high limit temp switch to trip?

Still suspicious.....

Please make sure that CO Detector is functioning properly until 'smell' is completely gone and furnace is performing like it was prior to this incident.

[beemerphile1]

The wasp nest was probably the issue.

Late now but the correct way to test a heat exchanger is by placing a smoke bomb inside the combustion chamber and looking for smoke where it doesn't belong. Any smoke bomb like sold as a novelty will work.

[ky-newbie]

Hi,

An update:

I had a certified mobile tech come out and check the furnace. He took it completely out and we both looked over the heat exchanger. No problems found. He did a thorough cleaning of the unit while it was out.

He did find a wasp's nest in the exhaust port, and said that could have been the problem. When he reassembled the unit and we tried it, it gave a "dusty" smell, like the first time in the season. It was nothing like the exhaust smell. He said that it should go away shortly, but I still have about 60% of the smell today.

I suppose the wasp's nest could have been the issue. I figured they had all gone south for the winter. 😉

Thanks!

[darsben]

If you have the make and model number you can probably find the service manual at;

http://bryantrv.com/docs.html

[ky-newbie]

Thanks. I believe the exchanger is toast. 😉

I picked up a large ceramic heater today, and I believe it will do until I can afford the repairs.

[Old-Biscuit]

Can't measure air temp with a laser (infrared thermometer).
You are probably measuring duct or register temps.

Being unable to hold hand over air flow coming out of register and the smell of exhaust is indicative of a cracked heat exchanger.

Do not run furnace.....CO kills

Pull heat exchanger an inspect before using it again.

[darsben]

Tomorrow let it run for a while with the windows closed and see if the CO detector alarms. If you can move the CO detector put it in the heater air stream.

[ky-newbie]

Yes, I installed a new smoke/CO monitor when I bought the RV this summer. I think I'm going to turn the furnace off, and use space heaters tonight. Hopefully, it's not that exchanger!! :E

[darsben]

What jumps to my mind is cracked heat exchanger. Do you have a carbon monoxide detector?