Troubleshooting an RV Furnace

The heater in your RV is going to run off of LP and 12 volt power. Now, this one happens to be a Suburban. We see duo therm over the years, hydro flame. This one is located down in the lower section. There's not a lot of maintenance that's required on the furnace, but there is a few things that you can do to make it run more efficiently.

First of all, to understand how the operation works. This furnace is going to provide heat into a plenum. Now, some of them put a full, like an HVAC plenum on the inside, on the bottom of the flooring section, and we have vents in there that provide a nice radiant heat. Other ones will have, we call them elephant trunks or tubes that will run in and out of cabinetry. If I got insufficient heating inside, I've got low air flow coming out the vent, the first thing I want to check is to make sure that I didn't shove something in one of the cabinets and bend or kink that hose that's in there, that's fairly common to do as we try to put more and more stuff inside or it may be one of the tubes just couldn't let go, it doesn't have a good connection to the vent on the outside, I also want to make sure outside here that I don't have anything blocking this outside vent here, I need to make sure that I get exhaust coming out of it.

Now there's a spider that loves the smell of propane and you'll get into some of the southern states where that and mud daubers and variety of different insects will just completely cake these up. And then it's not going to run. We're not going to get exhausted out of it. We're not going to be able to put it on to the inside. I also need 10.5 volts of battery power to be able to spark this, a lot of people don't realize it, even though this runs off of LP, we still need battery power to make it run.

A couple things we can check then inside, we're going to just take this out. Now, some of them, this one actually had a screw down here, we took it out beforehand, it was a little tough to get at. This is an older model, we're talking in 92 and this has never been out, so we had a pretty good challenge getting that out of here. And, here you get, you could see the vent. It's easy for them to get inside here.

There is some rust in here, too. So, if we start getting some buildup in there, I would go in and blow it out. All right and since this one doesn't have a chicken beak like the other ones do, I'm just going to use a little bit of tape to hold this up in place, so here is our, inside of our furnace, we've got our exhaust right here. It's the rusty one coming up, we've got our intake here. This is our gas line coming in.

Now we need 10.5 volts to make sure that we, not only opened the gas valve, but we opened this sail switch here, which is a little click you can feel. And that's going to start our ignition process in here. Now behind here is an orifice. And if we're starting to get a furnace that lights with a little bit of a puff or a bang at the beginning, sometimes they start up and they go kind of woof, that means that we may have an orifice here that's getting a little bit plugged. We may have, our intake is plugged.

And so we're getting a mixture that's not quite right for here, so we're going to have to take this out. And to do that, you're going to have to disconnect the valves and pull the end-in out quite a bit. And that's probably something you're going to take to a dealership, a repair facility, but as far as what we can do here, first thing, let's take a look at how we clean this out here, so I'm just going to grab an air hose and always use your safety glasses. 'Cause this, especially on the older one like this, we're gonna see a lot of rust come out of here and I'm going to actually stand back a little bit from it too, so I'm going to go in and just. And then, I'm just going to give it a little of this.

Kind of clean that whole compartment out, so I don't have a lot of stuff that could get sucked in there when I'm running the furnace. So then if I have no operation at all, what I can do is grab my multi-meter here or you can actually use just a simple little test light. So the first thing I'm going to do is put this here. I'm going to pop this off and our ground comes into the middle here and first we're going to check for voltage coming in. And we see that we have 12.05.

Now this lead here is my thermostat. And right now my thermostat is off. So it tells me that I don't have anything coming in here. Now, an easier way to do this if you don't want to take all that off, I'm going to pop this back on here, I can take my test light and just go in and find a ground, which is right here, first thing I want to test to make sure, okay, I've got power, I don't exactly what it is. And then I'm going to go down to my thermostat and I'm going to test the thermostat and we can see right now, we have no power, but I've got Stevie inside and he's going to flip the thermostat on.

And we see we've got continuity there. So the basics of the furnace then is make sure you got 10.5 volts, make sure it's coming in to the system here and that your thermostat is correct. To have a little more sufficient heating on the inside of it, check your vents for any obstructions. I have seen times where even the vents, now we see our furnace has kicked on here, I see even the vents inside the plenum sometimes, we'll get debris, people put rugs over the top of them and so forth. So make sure they're wide open.

Make sure you got good air flow coming through there and you'll have a better heating system.