Jayco service dept unable to fix furnace short cycling

Doctor Chuck · 10-10-2022, 04:31 PM

2020 248RBSW. Furnace has never worked right. Bought Feb '21. Never used furnace till Sept '21. We live in AZ. Short cycled from the get go. !st time in shop, they cut an extra vent in the wooden box the furnace sits in under the jackknife sofa. They thought inadequate air flow. No help. Next time in, they said it worked fine at 1000' elevation. I explained we live at 7000' and it doesn't work. They tested some parameters per Dometic and sent data to them. They then decided the propane pressure was too low, so increased it to 11.5. We took it out to camp and it continually short cycled again. It's still under warranty. Any recommendations? It's a 3hr drive 1 way to the service center and they've had it twice w/o correcting the problem. It has the underbelly. We get good air flow out the heating duct in bedroom, but little through the ducts in main cabin. Duct issue? Since it's still under warranty, what should I do???

**Midnightmoon** · 10-10-2022, 04:44 PM

When you say short cycle, do you mean that the furnace sill start and then run for only a few seconds and then shut down? Does it ever blow hot air during this short cycling or does it never actually fire the burner and continue to blow cool air?

Grumpy · 10-10-2022, 04:47 PM

Unfortunately it's the nature of the beast. High altitude has always been an issue with RV appliances.

Right from the web:

Unfortunately, the RV industry is based in Elkhart, Indiana. Elevation above sea level: 748 feet. Closet mountains above 6,000 feet: 560 miles away, in distant Tennessee. The Rockies are even farther, more than 1,100 miles away.

Quite frankly, many RV components are not designed for operation at high altitudes. And most of the industry has turned a blind eye (and ear) to the complaints of travelers west of the Mississippi.

Doctor Chuck · 10-10-2022, 07:10 PM

It fires the burner for 2-80 seconds only and will blow warm air. It takes forever to heat up the inside of the trailer.

**Midnightmoon** · 10-10-2022, 07:43 PM

If this was happening at a lower elevation, it may point to a simple sail switch failure. But, I think that Grumpy nailed it with his post concerning altitude.

Doctor Chuck · 10-10-2022, 09:58 PM

I appreciate the thoughts re: altitude. My last trailer was a 2010 Gulfstream and the heater worked fine as high as 10,000 ft. So I don't get why this new one won't work.

OnTheGo · 10-11-2022, 02:21 AM

The dealer's service reps knowledge of individual products seems to be random based on their experience.

I would contact Dometic (again, myself) and see if they can offer any different suggestions. Ask them if there is a rep with high-altitude experience. It's their responsibility to make it work. If they can't, Jayco needs to know about it and supply you with a furnace that will work.

mokurt · 10-11-2022, 05:25 AM

I would remove the duct vents and take look inside.
Our trailer had debris left in them from mfg.

Also some of the taping was inadequate.

RVermont · 10-11-2022, 06:06 AM

Interesting that they raised the propane level. I was under the understanding that the problem with high altitudes is lack of oxygen and the standard low elevation setting of 10.5 in h2o propane provides too rich of a mixture to burn correctly. I had read an article that some people lower the pressure to 8-9 and had success. Not sure if that is true or not. Might be worth a call to some rv service companies. There is guy in Oregon that has a pretty good following on utube. My Rv works. He has a service that allows you to ask question online and he works with you to get a solution

Grumpy · 10-11-2022, 06:50 AM

Quote:

Originally Posted by Doctor Chuck

I appreciate the thoughts re: altitude. My last trailer was a 2010 Gulfstream and the heater worked fine as high as 10,000 ft. So I don't get why this new one won't work.

We have seen numerous posts here where people in Colorado have had issues with their furnace and even with their propane fridge.

Randy · 10-11-2022, 07:07 AM

Hi Doc- I feel your pain with the long drive to the dealer. I live at 7,000 feet, and camp and play up tp 9,000 feet. Over my lifetime I have owned maybe 7 rv's and none ever gave me heater grief because of elevation. I did have a sail switch fail on me a couple of years ago.

Randy · 10-11-2022, 07:12 AM

PS to my last post- That sail switch was dirty... after cleaning it, it tested fine, but still "short cycled" They are cheap so I replaced it anyway, and the heater has worked fine ever since

Cincinnati Kid · 10-11-2022, 07:41 AM

Yes, our sail switch tested fine when removed, but still didn't work. Replace it yourself, save the 6 hour drive. There are only about 4 things that tend to go wrong with them. You might as well get on youtube and learn to fix it, because you will be out of warranty and it will probably break again.

JohnWedell · 10-11-2022, 07:45 AM

I would have it removed and run it on a bench. If it runs with no problems then it has to be airflow. I had the same problem with a starcraft travel trailer. It ran fine on the bench but would never run inside Trailer I guess it was a poor engineering design in the duct work I wound up getting rid of it, couldn't deal with it anymore

us71na · 10-11-2022, 11:18 AM

If it tries to start but doesn't fire the burner, the sail switch is most likely at fault. If it turns on the burner and runs for a while, it is most likely the firebox over temp switch that is shutting it down. The most likely cause for over temp is inadequate airflow through the heat exchanger. Your duct work is the likely culprit. Check the cold air return, the filter could be clogged. If you are not getting good air flow out of the vents it is likely there is blockage in the vents. A good Borescope Inspection snake will let you see inside the duct work.

Parrott · 10-11-2022, 01:48 PM

The installation and ductwork on these campers and motor homes is sloppy at best. Bench test to totally eliminate installation.

Gary207 · 10-11-2022, 02:57 PM

Just for the heck of it check that the fan motor is running in the right direction and the blower was not put on backwards. No insulation inside the blower wheel. Make sure you have a path for the return air flow.

Doctor Chuck · 10-11-2022, 04:24 PM

It's been bench tested at least once and the service center claims it was fine. not sure what u meant by "Bench test to totally eliminate installation." Do u mind clarifying for me?

Doctor Chuck · 10-11-2022, 04:27 PM

Quote:

Originally Posted by Gary207

Just for the heck of it check that the fan motor is running in the right direction and the blower was not put on backwards. No insulation inside the blower wheel. Make sure you have a path for the return air flow.

the fan motor seems to be in correct direction. What do u mean by "Make sure you have a path for the return air flow." Sorry, I'm not versed in these furnaces.

Grumpy · 10-11-2022, 04:42 PM

Quote:

Originally Posted by Doctor Chuck

It's been bench tested at least once and the service center claims it was fine. not sure what u meant by "Bench test to totally eliminate installation." Do u mind clarifying for me?

If the duct work is blocked or obstructed they will short cycle because of inadequate air flow so they take it out and run it while on the service bench to see if it functions properly.

This is not to be critical since everybody is trying to help, but I think many have overlooked the fact that you stated your dealer said it worked fine at 1,000 feet which would eliminate the blockages, faulty sail switch etc. I'd bet the bank that it is truly an elevation issue.

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