New Cougar - Furnace wont heat above 60

[nebmike]

Just took delivery of a brand new Cougar 33SAB travel trailer. For some reason the furnace will not heat the inside of the unit to more than about 58-60 degrees... its been about 25 degrees overnight.

This is my third camper and I've always been able to heat to 70+ at temps well below 25 outside.

Fan seems to be pushing an appropriate amount of air, it just seems like the air coming out isn't as warm as I'm used to.

Also, it seems as though every few minutes it'll blow cooler air for a while and then go back to somewhat warmer.

Help? Really not wanting to wait weeks for a warranty appointment. 😕

Thanks in advance!

[Boon_Docker]

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[Boon_Docker]

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[nebmike]

myredracer wrote:

Can't find furnace specs for that model. What does whatever info you have say it should be? Never, ever trust what an RV dealer tells you.

I called Keystone and was told the 20k btu furnace is what this unit is supposed to have. Stupid, because they put a 30k in all of their 5th wheels... none of which have the square footage of this TT.

[myredracer]

nebmike wrote:
So I pulled the rear panel off the unit -- its an SF-20FQ... which pisses me off because I specifically asked two different people at the dealership and was told it had a 30,000 btu furnace. 😕

Anyway, this is a 37' long camper with 3 slides -- is this just simply not enough furnace for me?

Our TT is 29' (including the A-frame) with one slide. Has a 20K Btu furnace but have not checked the label. 20K Btu is borderline for our length in my opinion from what we have experienced.

Can't find furnace specs for that model. What does whatever info you have say it should be? Never, ever trust what an RV dealer tells you.

Many TTs have poor insulation, esp. in the ceiling where you can find voids and compressed insulation. I would hazard a guess that the quality of workmanship in the insulation is not the greatest. Could check by taking a skylight trim, speaker, etc. however not anything you do can do about it. Slideout floors aren't insulated and 3 of them will increase heat loss a bit.

[nebmike]

So I pulled the rear panel off the unit -- its an SF-20FQ... which pisses me off because I specifically asked two different people at the dealership and was told it had a 30,000 btu furnace. 😕

Anyway, this is a 37' long camper with 3 slides -- is this just simply not enough furnace for me?

[myredracer]

Our furnace would not heat up the interior in temps below 40F and would otherwise take a long time to heat the TT. Ran continuously all night in cold weather.

I pulled out a 4" duct that ran under the floor and came back up in the kitchen. This duct was partially collapsed and was uninsulated in the underbelly space and sat directly on top of the cold coroplast. I replaced the 2" duct to the bedroom with 4". Insulated the duct under the floor. Also sealed up ALL the gaps/holes through the floor. There was a 10x10" hole into the underbelly right next to the furnace which would have been sucking in cold air from outside.

Now it works like a charm and heats up quickly and keeps the interior comfortably warm. The first thing I noticed is how fast the air comes blasting out the vents now. The dealer said it was the sail switch and they replaced it but did nothing to help. Pics and detail on this thread. under-performing furnace Poor design and workmanship - plain and simple...

I would look at how your ducting is run and also if there are a lot of holes through the floor. Could possibly be a cause similar to what I found. The post above also suggests blocked ducting as a potential cause.

[dcg9381]

We supplement with electric heat as to reduce the propane load.
The most common issue with Keystones that are having heater problems is crappy venting. You (or your dealer, depending on how many weeks/months it'll take) need to drop the underbelly and inspect the furnace duct work. Often the ducts are not cut to length and end up kinking or with sharp bends.

One indication of poor duct work would be poor airflow out of the furnace in general.

My experience with propane furnaces is that they'll generally heat you out of the RV if setup properly.

[TakingThe5th]

It sounds a lot like a high limit switch to me too, but have you eliminated the possibility of a bad thermostat? Crank it up and see what happens.

Since we are also talking heat ducts, be aware that you might have a small (2 inch) hose going to the basement area. Not sure of that but my old 318SAB worked that way. Probably not your problem, but just for giggles check your basement area to see how toasty it is in there.

[spadoctor]

This trailer may use heat from the furnace to heat the underbelly tank area....if so there may not be enough BTU being sent into the living space.

[wasatchmtnatvr]

Your description your model series is SF. Probably an SF-35Q, my hunch. Pulling back panel that contains 3 discharge ducts will reveal a logo (sticker) of model number. Also limit switch with 2 wires attached is also right there. If your handy and can swing a wrench, just replace limit switch yourself. Also add an additional 4th 3" vent from the side not used and determine where you can route it to interior based on cabinetry, routing location. Cost is cheaper than gas to take rv into dealer, and your downtime that you don't have your rv. You will get the satisfaction of fixing it yourself. Also dealer probably won't be successful in resolving issue unless they add an additional vent anyway. There is no downside to additional vent as long as you have the real estate for routing the ducting and a discharge vent location.

[We_Cant_Wait]

You've had 3 other TT's with no problems, where they all Cougars too? If not it could well be that this TT is not insulated as well as the other 3 were.

[nebmike]

wasatchmtnatvr wrote:
Please post model number of furnace. This is important. Either furnace hitting high limit switch which cause an open circuit, which deletes power to circuit board, ceasing flame operation, and flame will shut off. When limit cools contacts close, causing power to circuit board, 24 seconds later, flame will re-appear. When this sequence occurs you feel cooler air than hot , but it will not be cool air. Cause, inadequate air flow usually caused by not enough heat discharge ducts for furnace to vent heat out, or breathe. If soft ducting you should have a minimum of 4 full size tubes coming off of furnace shell and registers fully open at discharge within interior. Virtually every furnace will work better if you can install an additional discharge warm air duct.

Its a Suburban, but I cant find a specific model number in any of my documentation or visually on the unit itself. Any tips on how to identify it? I think it might be an SF-30FQ, which the book says should have a minimum of three 4" ducts...

Its got three 4" ducts coming off the back and two smaller 2-2.5" ducts coming off of one side (with spots to add two more ducts on the other side). I even removed the floor vents so the air flow was totally unrestricted. The fan seems to be pushing a strong amount of air at all of the vents.

[wasatchmtnatvr]

Also if warm air is blowing toward interior t-stat it can trick t-stat to think its interior temp. is satisfied. Flame will shut off, now air blowing toward t-stat not as hot and t-stat recognizes slightly cooler interior air than setting and re engages. Flame re-establishes. Cycle repeats itself. Or if t-stat has an adjustable heat anticipator it should be set to .6 - .8. Old school bi-metal t- stats have this anticipator adjustment. Unsure about yours though.

[dougrainer]

What Model/BTU furnace? From your description, the Hi limit is kicking in and out. That means that either there is a restriction in one on the Furnace hoses or they did NOT run enough hoses to allow the furnace to run correctly. There is a specific amount of exhaust vent hoses to allow the furnace heat to run thru out the RV. Also, it is not unusual for the OEM to install a TOO Small BTU furnace. Your model should have at a minimum at 30k BTU furnace. Doug

[wasatchmtnatvr]

Please post model number of furnace. This is important. Either furnace hitting high limit switch temp. rating, which cause an open circuit, which deletes power to circuit board, ceasing flame operation, and flame will shut off. When limit switch cools, the contacts close, causing power to re-energize the circuit board, 24 seconds later, flame will re-appear. When this sequence occurs you feel cooler air than hot , but it will not be cool air. Cause, inadequate air flow usually caused by not enough heat discharge ducts for furnace to vent heat out, or breathe. If soft ducting you should have a minimum of 4 full size tubes coming off of furnace shell and registers fully open at discharge within interior. Virtually every furnace will work better if you can install an additional discharge warm air duct.