Weird Heater Issue

[JoeWebPage]

We have a 2012 Durango 325RL, and overall have had no real issues. But this one is really annoying. We're still under warranty, so guess when this trip is over, it's back to the dealer.

Ok, this is a pretty weird thing, but hoping somebody has heard of it or something close.

Our heater works great ... most of the time. The issue was thermostat ... or so I thought. It's been cool where we are at, so have the thermostat set at 63 for night. The heater comes on when it needs to. Then ... maybe on the next start up or maybe a couple later, it doesn't run. The only way I can get it to start back up is to put the thermostat switch to off and then back to on. Then it operates "normal" ... sometimes. Always starts back up, but eventually it will fault.

I thought it was the thermostat, so bought a really nice digital one. Same thing. So, it's not the thermostat. When this first happened, I included it in the list of issues we had with the unit, but the dealer obviously couldn't find anything wrong (BTW, very few issues and dealer fixed all our list, which was pretty short). I think the only way this can be duplicated is to live in it where it's pretty cool or even cold.

So, anybody have any body have any ideas. I'm thinking either the control board for the heater or the heater itself. It's a Suburban.

[JoeWebPage]

Ok, that previous post didn't fix it.

At last, at last ... the heater has been fixed. The dealer tried all kinds of stuff to get it running and finally called Suburban and talked to them. He said their suggestions were really helpful ... leading him to believe the "hitemp" sensor was faulting because of restricted heat output.

The heat "hoses" that came from the heater and go to the camper's duct work had some pretty sharp bends in them and they "straightened" the hoses. They also connected an additional 2" hose that simply dumps into where the water heater is. Finally (we had a really nice long chat and on site explanation of everything) he noted that the sliding panel that's between the heater and the "garage" might be blocking the intake of air for the heater. He suggested leaving the panel slightly open. I think I will probably put some sort of vent device so as to stop any critter attacks (we don't currently have critter issues ... but you never know). Now I'm "Joe Happy Camper".

[JoeWebPage]

Ok, update. I got the camper back today. Haven't had a chance to test the heater yet, but am reserving a camping spot for next week.

Sounds like a lot of the suggestions sort of revolve around what they said they found. I had emailed Suburban and they said they wouldn't give any suggestions to the end user, that the dealer could contact them and they would suggest solutions.

They told me there were two issues. I'm going to believe they tested it, as the thermostat was set at 87 when I got it home! Anyway, they said the delivery of propane was not quite what it should be and that there was oil in the propane regulator (sounds like related issue). They replaced the regulator.

I will update after the camping trip next week.

[MarcusJ]

I have a 2000 Thor 26GT with a Suburban furnace, SF-25. After I took the trailer on a rather bumpy 10 mile gravel road in the wilderness, the furnace didn't ignite.
It was running fine when connected to AC power back at the RV park. But that weekend, it just blow cold air (did not try to ignite at all). It was 39 that night, needless to say there was plenty of cold air... Battery voltage was fine (~12.5V) , propane tanks full, new regulator too.

Back at the RV park, I plugged it in and it operated fine (~13.5V). I thought perhaps the sail switch or the blower motor was the issue. When AC power is on, the furnace fan would slightly speed up and then ignite fine. But on battery alone it would not cycle. There was plenty of air flow either way, so I didn't consider the blower motor failure. A month later and next trip when I arrived, even the generator to simulate AC power didn't work and it was 45 in the RV that night...

Taking out the furnace is a little hassle, and I found everything was pretty clean. I blew out some dust out of the fan cage/switch area anyway. Looking at the sail switch, there is a thin metal lever arm that extends from the switch into the chamber. Moving the lever arm, I noticed that it took excessive travel for it to engage, almost at the limit of travel. So I carefully re-bend the arm "straight" so that it took less travel for the switch to engage (click). It fired right up when I reinstalled the furnace both battery and AC power.

So my observations were that perhaps the blower motor is running slower than new, (doubtful because it blows plenty strong), or after 13 years and bouncing around on that road the sail switch level arm sagged to far to engage the switch, which when adjusted a little did make it work again. At least for now, until I order a new sail switch.

Tonight, off to the woods again, suppose to be around 55 tonight so...

[aruba5er]

I don't think hish pressure would kick it out as there is no high pressure switch in the furnace. However like mentioned above, overheat can and will shut you down.Like DAZED, mine got over hot and shut down. The manufactuer had only installed 2 outlets into the furnace and all the air had to exit those 2. I added 2 and redid one more giveing me 5 outlets. The noise went way down and the temp is around 120F. Never a problem again. I'd test temps before hauling my rig anywhere.

[DazedNConfused]

Puddles wrote:

DazedNConfused wrote:
There are a number of safety protocols on a propane furnace that, when tripped, will force the furnace into a "Lockout" mode. That lockout is designed to keep the furnace from firing up and protecting the trailer's occupants. I don't have it handy, but I've seen some flow charts that document the various safety devices...and how they all operate. One thing to check is the temperature coming out of the vents. I believe when the furnace detects a heated air temperature of 160 degrees or more, it will lock it out. This is what happened to mine. When I measrued the temperature at the vent closest to the furance it was a very high 178 degrees -- so that's obviusly over the 160 lockout temp...and what was causing my furnace to run for a cycle, stop, and then not start again until I pulled and reinserted the fuse -- which reset the lockout condition.

Have you taken the temp at the vents and at the return to see where your numbers are? Just another idea.

- DNC

Curious as to what caused the overheating problem?

Ya'know...I still don't know. I was about to go through the process of pulling the furnace and putting it on the bench to diagnose it...but it was a new camper...and figured i better let the warranty take care of it. I don't know how much time they spent diagnosing....but know they ordered a new furnace...and it's in the shop now getting replaced (along with a number of other items i let build up before making the 3-hour round trip to drop it off). I have heard, though, that even things like high propane pressure could cause this. If they solve the problem by full replacement, I won't know exactly what was wrong. But I will post if/when I find out.

[Monaco_Montclai]

Mine will try three times to lite, a normal thing for me.have to reset after that. Happy-camping

[Puddles]

DazedNConfused wrote:
There are a number of safety protocols on a propane furnace that, when tripped, will force the furnace into a "Lockout" mode. That lockout is designed to keep the furnace from firing up and protecting the trailer's occupants. I don't have it handy, but I've seen some flow charts that document the various safety devices...and how they all operate. One thing to check is the temperature coming out of the vents. I believe when the furnace detects a heated air temperature of 160 degrees or more, it will lock it out. This is what happened to mine. When I measrued the temperature at the vent closest to the furance it was a very high 178 degrees -- so that's obviusly over the 160 lockout temp...and what was causing my furnace to run for a cycle, stop, and then not start again until I pulled and reinserted the fuse -- which reset the lockout condition.

Have you taken the temp at the vents and at the return to see where your numbers are? Just another idea.

- DNC

Curious as to what caused the overheating problem?

[Puddles]

DazedNConfused wrote:
There are a number of safety protocols on a propane furnace that, when tripped, will force the furnace into a "Lockout" mode. That lockout is designed to keep the furnace from firing up and protecting the trailer's occupants. I don't have it handy, but I've seen some flow charts that document the various safety devices...and how they all operate. One thing to check is the temperature coming out of the vents. I believe when the furnace detects a heated air temperature of 160 degrees or more, it will lock it out. This is what happened to mine. When I measrued the temperature at the vent closest to the furance it was a very high 178 degrees -- so that's obviusly over the 160 lockout temp...and what was causing my furnace to run for a cycle, stop, and then not start again until I pulled and reinserted the fuse -- which reset the lockout condition.

Have you taken the temp at the vents and at the return to see where your numbers are? Just another idea.

Curious... what caused thew overheating?

- DNC

[DazedNConfused]

There are a number of safety protocols on a propane furnace that, when tripped, will force the furnace into a "Lockout" mode. That lockout is designed to keep the furnace from firing up and protecting the trailer's occupants. I don't have it handy, but I've seen some flow charts that document the various safety devices...and how they all operate. One thing to check is the temperature coming out of the vents. I believe when the furnace detects a heated air temperature of 160 degrees or more, it will lock it out. This is what happened to mine. When I measrued the temperature at the vent closest to the furance it was a very high 178 degrees -- so that's obviusly over the 160 lockout temp...and what was causing my furnace to run for a cycle, stop, and then not start again until I pulled and reinserted the fuse -- which reset the lockout condition.

Have you taken the temp at the vents and at the return to see where your numbers are? Just another idea.

- DNC

[enblethen]

I would go back and check connections. Look and tighten incoming 12 volt DC. Check the thermostat wires for connection tightness at the furnace.

[JoeWebPage]

enblethen wrote:
If the fan does not start up, it would not normally be sail switch issue.
It could be thermostat or wiring to furnace, time delay relay (depends whether relay is on circuit board or separate part)
2012 rig should have later model circuit board with time delay on board.
Make and model of furnace would be helpful.
Is the rig still under a warranty? If so try get them to fix it. Warranty of furnace can be separate from rig.

As posted in original post, unit is still under warranty. Checking the book on the heater shows it also has a 2 year warranty, same as the camper, so is also under warranty. I also mentioned that is a Suburban heater, but here is the model number SF30f.

Thanks all for replies, time to start checking all those items.

[Me_Again]

Check the 12V connections to the unit. Remove and re-seat all the cables that pull into the circuit card.

It also could be that they did not install enough ducking and it is doing an over temp shutdown. Make sure all your registers are open for max air flow. It might have extra blank outlets, if you can remove one of those that lets the heat come into the unit without damaging anything, that is a good air flow test. Seems the new units are very sensitive to air flow. Might just start with this.

Chris

[enblethen]

If the fan does not start up, it would not normally be sail switch issue.
It could be thermostat or wiring to furnace, time delay relay (depends whether relay is on circuit board or separate part)
2012 rig should have later model circuit board with time delay on board.
Make and model of furnace would be helpful.
Is the rig still under a warranty? If so try get them to fix it. Warranty of furnace can be separate from rig.

[JoeWebPage]

enblethen wrote:
The sail switch is a small switch with an arm sticking into the circulation portion of the furnace. It is activated by the fan during start up. The switch statys operated during furnace operation.
If the sail switch does not activate the igntion system will not operate.
It has a very small operator on the switch. A small spec or so of debris can prevent it from operating.

Thanks, I'll have to take a look at that. However, I never hear the fan start up at all, but I might have slept through that I suppose. At this point I'm willing to try anything that someone can come up with.