Heating issue

[ED R]

I have a 2018 montana 305rl just had it out this past weekend the heat could not keep up with the 29 degree temp the unit kept shutting off way below the set temperature is this normal or do I have a problem with the Furnance and if so any ideas of what it could be

[Cat320]

Assuming you are plugged in to shore power, get a couple of Lasko towers.

[jimcol]

The thermostat may be the issue. You might try increasing the set point a few degrees and see if the furnace runs longer.

[mlh]

Cut the thermostat up until you are comfortable.
We have the same issue at home. We have a mini split and the thermostat is in the inside unit. As the outside temperature varies we haft to adjust to keep the inside temperature at about 70 to 72.
Lynwood

[DutchmenSport]

No doubt your thermostat on the wall is absolutely NOT calibrated with the furnace, so just forget about the dial read out temperatures on the actual thermostat.

We set an independent thermometer (in door / out door) battery powered thermometer at the location we want to control the temperature and simply adjust the dial on the furnace thermostat until we get the temperature we want at that location.

We usually keep the main unit right at the furnace thermostat. I put a hook right beside the thermostat so it can hang there. And yes, the actual temperature at that location is off ... by a lot.

And here's another consideration ... no 2 spots in the camper are going to be the same temperature either. You could have a variance of 5 to 8 degrees (or more) between one end of the camper and the other. Why? Because our campers are simply not insulated that good, the run of the air ducts from the location of the furnace is different in every room, some rooms get a stronger force of air than others, and some spaces in the camper are much larger than others (causing the smaller spaces to heat up faster and hotter than every where else).

So, the best you can do is place the independent thermometer where you want the heat to maintain your comfort level and keep adjusting the furnace thermostat until you reach that point.

Many of us seppliment the furnace with electric heat. If you have a fire place with a heater, turn it on. Place a ceramic heater in the coldest spot in your camper to keep it comfortable. Run a fan to help circulate the air so warm air circulates to the cooler spots in the camper and evens the temperature out through out the entire camper.

But, long story short ... disregard the numbers on the furnace thermostat. They mean absolutely nothing. Do your own calibration..... the same is true if you have an RV oven too. The numbers on the dial mean nothing except which direction to turn the knob so the oven gets hotter or cooler.

And one more note: If you are using your camper and the outside temperature is near freezing or below, you can expect your furnace to run a lot ... almost non-stop. If you have a Air Conditioner with the Heat Pump feature, the heat pump will work only to about 40 - 45 degrees (outside) and then it blows nothing but cold air.

[Daryles]

We have found that our Dometic capacitive touch thermostat is off (high) by 4⁰F from actual room temperature.

[Bourbon County]

It's not likely this simple, but might be worth a look.

Is your thermostat located on the interior wall directly above the short counter section that most everyone uses as a coffee bar? If this is the case, the warm air rising from the coffee maker could be causing the stat to sense higher temperatures than the actual ambient in the trailer.

That's a bad place to locate a thermostat, but the alternatives are much worse. It should be located on an interior wall away from drafts and preferably in the return air path. Typically the risers on the stairs are slotted and used for the furnace return so in that sense, it's good. The fact that it's directly across from the exterior door is really bad; RV doors aren't really that air tight and every time it's opened you are exposing the stat to a blast of outdoor air temps.

Take a look and see if you are using a coffee maker or any heat producing appliance on that short counter section. Here's a hint: the coffee maker is much easier to move than the thermostat.

[jsb5717]

We have the same year and model as you. The furnace is capable of keeping the coach warm at those temps. As has been stated, it's likely the thermostat. We replaced our OEM thermostat several years ago with the MicroAir. The only time I notice that the system gets fooled into a false temp is when the sun is shining directly through the door window or the skylight onto the thermostat. Otherwise it holds temp well. We run our coffee maker by the stove so there's nothing else influencing the thermostat.

It should be a fairly simple test to jump the blue wires on the furnace, effectively bypassing the thermostat, to see if it still turns off. With the blue wires jumped it should run non-stop. So if it turns off then you know there's a faulty function on the furnace, not the thermostat. It's a place to start to try to identify the weak link.

FWIW, I've heard that running the electric fireplace can give the thermostat a false reading. However, we often run both in cold weather and haven't had that issue.

Also, FWIW, our furnace has failed 3 times since new. First failure was at about 2 years old. There are several things that can cause a furnace to fail and you either learn how furnaces work and how to fix them or you pay someone who can. I went the learning route. I've had to replace the propane regulator (not on the furnace but directly impacts function), Limit Switch, and Diffuser/Burner. I now keep in the trailer every possible replaceable part for the furnace so I don't get stuck somewhere and troubleshooting is easier...including a spare propane regulator.

One more thing. If you are handy, and haven't done so yet, it would be a good exercise to open up the furnace and tear it down. It's not nearly as complicated as it sounds and it's even easier since you have exterior access. You do have to disconnect the propane but that's not hard. I would inspect the parts...especially the burner assembly and igniter. The diffuser can rust over and cause problems with a clean burn. Anyway, that's what I would do. YMMV

[rcc now]

I think your unit is short on supply ducts coming off the furnace. Without enough supply ducts to move the air, the furnace will overheat and shut down. Look at your Suburban manual and I think you will find your unit has less than the minimum required which is three 4” round ducts. My unit only has one 4” and one 2” duct which is not enough and my furnace does the same thing that yours is doing. Keystone isn’t using enough ducts and over time the overheating will burn out the furnace.

[jsb5717]

Originally Posted by rcc now

I think your unit is short on supply ducts coming off the furnace. Without enough supply ducts to move the air, the furnace will overheat and shut down. Look at your Suburban manual and I think you will find your unit has less than the minimum required which is three 4” round ducts. My unit only has one 4” and one 2” duct which is not enough and my furnace does the same thing that yours is doing. Keystone isn’t using enough ducts and over time the overheating will burn out the furnace.

Perhaps a good thought but likely not the issue unless the OP has blocked some vents. The furnace is an Atwood and identical to ours in the same trailer. We don’t have an issue of too few ducts. The issue will be internal to the furnace itself or the thermostat

[Mikelff]

Originally Posted by ED R

I have a 2018 montana 305rl just had it out this past weekend the heat could not keep up with the 29 degree temp the unit kept shutting off way below the set temperature is this normal or do I have a problem with the Furnance and if so any ideas of what it could be

Like others have said, it’s most likely your thermostat. We supplement our furnace with a small electric heater in the master bedroom and the fireplace heater. You need the furnace to run to keep your pipes from freezing. You need to adjust your thermostat to run until you get to a comfortable Temperature. The temp setting on the thermostat will likely be much higher than the actual inside temp. Fortunately for me, it’s only about 3-6 degrees higher than actual inside temp.depending on how cold it is outside. It’s amazing how much heat the small electric heaters put out, and mine is very quiet . Keeps us cozy at about 73-74 degrees actual inside temp. I have an Atwood heater that works well and keeps us warm in freezing temps but sucks the propane. The electric heaters help mitigate the propane use. If you do much camping in freezing weather, there is an aftermarket electric furnace that attaches to the back of your propane furnace and puts out as much, if not more, heat than your propane furnace and uses the same ductwork. You can run both at the same time if need be. The electric portion can run as much as you need if hooked up to 50 amp pedestal. This will also keep the underbelly heated. It’s not a cheap add on but cheaper than burning all that propane. I have a friend that goes deer hunting and sometimes elk hunting and has the add on electric furnace. He said it was best money spent. Don’t know where he stays but he has pedestal 50 amp electric and runs that furnace almost 24/7. It’s covered in his camp fee. He said he carried 4, 30 gal tanks before he got the add on.2 in the rig and 2 in the truck bed, and would have to refill at least all 4 of those tanks during his 7-10 day stay.