Furnace runs no heat.

[VWFridolin]

Hello All!! I have a 2006 Forrest River Surveyor 303. Having furnace issues. I have two full tanks of propane and the stove works fine. The thermostat will turn the heat on but it only blows cold air for serial minutes then shuts off. Not sure if I have a pilot light and where it would be to check it if so. We just bought camper to move into and got to get heat working. Any help would be appreciated. Thanks!!!

[D W]

Which make/model furnace do you have?

[boondocking]

How many times have you tried running it?
Sometimes it takes more than a few tries to purge the propane line if it hasn't been used in a while.

[VWFridolin]

Originally Posted by boondocking

How many times have you tried running it?
Sometimes it takes more than a few tries to purge the propane line if it hasn't been used in a while.

It has been sitting for many years. No idea how many. I bought it from a 94 yo man. Haven’t tried to start it but two times with no luck. So should I keep restarting it until hopefully the heat kicks in? Does it have a pilot light? I wasn’t sure what needed to be done. Thanks for all the advise.

[VWFridolin]

Originally Posted by D W

Which make/model furnace do you have?

Not sure truthfully I will look tmr and post you back. Thanks

[emm-dee]

I agree with boondocking post. Sometimes can take 5-6 attempts to get the furnace.

When you do get it to start putting out heat I recommend you leave the exterior door/s open. You're going to get a lot of stink...a big lot. Also, you might even get some smoke so be prepared for the smoke alarm to start its thing. Don't worry..it will clear up. Be patient.

[Nick Danger]

Do you hear a "clicking" at all? If so it means it's trying to light the burner. If not, you may have an issue with the igniter. I have turn my thermostat up higher than normal settling to get it to fire the first time of the season and then set it back to normal after its fired up.

[mickw]

Originally Posted by Nick Danger

Do you hear a "clicking" at all? If so it means it's trying to light the burner. If not, you may have an issue with the igniter. I have turn my thermostat up higher than normal settling to get it to fire the first time of the season and then set it back to normal after its fired up.

We bought our used 2304s Rockwood 4 years ago used. First time we used the heat nothing came out of the duct work, or very little heat. After removing the duct work and taking it outside, we dumped about half a bucket of mice condominium crap. The heat works now. We also put screen on the inside of the duct caps, to keep those little monsters out. Good Luck

[welfarecop]

Check the thermostat. We had the same problem. It was set on "high" which meant is was blowing outside (cold) air at the same time the heater was trying to work. We set it to "auto" and it worked fine

[Larry-NC]

Originally Posted by welfarecop

Check the thermostat. We had the same problem. It was set on "high" which meant is was blowing outside (cold) air at the same time the heater was trying to work. We set it to "auto" and it worked fine

This doesn't make sense. RV furnaces have two completely separated closed loops, each powered by a separate blower. There are two squirrel-cage blowers, one for each loop, mounted on opposite ends of a single motor.

One loop draws in outside air to the firebox and exhausts combustion products to the outside. The other loop draws inside air to the plenum (around the outside of the firebox), and then out through the vents inside the RV. There's never any outside air blown into the trailer. (The plenum around the firebox serves as a heat exchanger.)

When the fan is set on high (in some RVs), the fan blows continuously. That unheated interior air feels cold when it's blown on you, but it is NOT outside air. As you discovered, setting the fan on Auto causes it to only run when the furnace is operating.

[Flybob]

Two things to try. Need to do both.



1 Light a stove top burner and let it burn for a minute or so to purge lines.


2. Pull the fuse that protects the furnace lines. After a minute or so replace the fuse and try again. If the furnace attempted to light several times but failed, it may have gone into safe mode and will not light until it is reset. Removing the poser will reset it.

[Larry-NC]

Originally Posted by VWFridolin

Hello All!! I have a 2006 Forrest River Surveyor 303. Having furnace issues. I have two full tanks of propane and the stove works fine. The thermostat will turn the heat on but it only blows cold air for serial minutes then shuts off. Not sure if I have a pilot light and where it would be to check it if so. We just bought camper to move into and got to get heat working. Any help would be appreciated. Thanks!!!

To provide specific help, we REALLY need to know the furnace model. And it seems like you have not reported what you are hearing. Diagnosis of the furnace is best done by listening.

The Suburban SF-series furnaces have been widely used for decades (there's one in our 2002 Nash). They have Direct Spark Ignition (DSI), an electric spark ignites the fuel when needed. There is no pilot light. There are maintenance manuals in the Library (towards the top left of your screen).

Their lighting sequence goes like this:

1. When you call for heat (switch goes from Off to Heat and Thermostat is set higher than ambient temperature):
2. After about 10 seconds, blower motor begins to run. One blower circulates air in the trailer; the other purges the firebox.
3. The sail switch senses whether the blower is running fast enough for safe operation. If not, everything stops. The furnace won't attempt to light. To force another attempt by turning the thermostat switch to Off, then back to Heat.
4. If the sail switch senses that the blower is running, then after 15 seconds or so, you will hear a clunk (solenoid opens the propane valve allowing gas flow) and then a tick-tick-tick sound for about seven seconds (electric spark to ignite the gas). If the gas ignites, you will hear a whoomp sound and heat will be provided.
5. If ignition is not sensed in seven seconds, the firebox is purged again and ignition is re-attempted. Steps 2-4 are repeated twice more. After that, the furnace gives up and stops. You must turn the thermostat to Off and back to Heat to start another cycle.

[Larry-NC]

Originally Posted by Flybob

Two things to try. Need to do both.

If we're guessing, there are really three things;

Originally Posted by Flybob

2. Pull the fuse that protects the furnace lines. After a minute or so replace the fuse and try again. If the furnace attempted to light several times but failed, it may have gone into safe mode and will not light until it is reset. Removing the poser will reset it.

Poser? Probably meant fuse, right?

In my experience it is not necessary to remove the fuse. Simply turning the thermostat switch from Heat to Off and back to Heat is sufficient to reset the control board.

Originally Posted by Flybob

Two things to try. Need to do both.

The third thing is to check the outside vents and make sure they are not clogged. Mud daubers (the wasps that like to build those clay nests that look like organ pipes) love to build their nests in the furnace vents.

[5picker]

Lot of good guesses but that is all they are until we know for SURE what make/model furnace you have.

Some do have pilot lights (basic furnaces/no control board) some have DSI (direct spark ignition and control boards) and the troubleshooting steps for each are different.

Give us something to go on.

[jeff64]

On a 14 y.o. tt you could have a bum lp regulator too. Even though a stove burner lights the systems require 11.5 " W.C. that's <.5 psi. hard to measure without rigging up a manometer, which can be a PIA. New regulators are ballpark $50.

[emm-dee]

Originally Posted by jeff64

On a 14 y.o. tt you could have a bum lp regulator too. Even though a stove burner lights the systems require 11.5 " W.C. that's <.5 psi. hard to measure without rigging up a manometer, which can be a PIA. New regulators are ballpark $50.

Or, the supply could have been turned too fast. I’ve had that happen on my Blackstone and there’s enough flow to get a flame but only a little one. The spark ignition doesn’t work very well then so I light it with a handheld lighter.

Turning the supply off for about three minutes or so resets it to normal.

[Frierson]

I am not sure if anyone has mentioned this so far or not, if so I apologize.
In our Cherokee, there is a panel next to the door above the counter to check the Fresh Water, Grey Water and Black Water Tanks, at the bottom is a switch for "Heat" and a switch for "Pump". If you have this panel the Heat Switch may need to be turned on for your furnance to light. We have had our camper for 2-1/2 years, only used the furnace once. Good luck.

[VWFridolin]

I do have a Suburban SF-30F. The thermostat will click twice and blower comes on and it will run for a while air comes out but it’s cold never gets hot and then cuts off. My stove and water heater both light fine. Sorry for late reply had to work today. Thanks for any help!!! We will be moving into camper and I got to get heat working.

[MR.M]

Originally Posted by VWFridolin

I do have a Suburban SF-30F. The thermostat will click twice and blower comes on and it will run for a while air comes out but it’s cold never gets hot and then cuts off. My stove and water heater both light fine. Sorry for late reply had to work today. Thanks for any help!!! We will be moving into camper and I got to get heat working.

You need to be good with a meter . fans kicks on the shuts off first strp sail switch not making contact . need to check continuity while fan is running . if you have continuity through sail switch but still not ignition ie sparking click it could be high limit at the rear of heat exchanger. if you get continuity through sail switch when fan is running and hi limit has solid continuity and still no spark or smell of gas then control board . if you smell gas but not lighting flame then it could be control board , igniter . clogged exhaust from mud dubers etc .

[Larry-NC]

Originally Posted by VWFridolin

I do have a Suburban SF-30F. The thermostat will click twice and blower comes on and it will run for a while air comes out but it’s cold never gets hot and then cuts off. My stove and water heater both light fine. Sorry for late reply had to work today. Thanks for any help!!! We will be moving into camper and I got to get heat working.

Read Post #12 again.

It doesn't matter what the thermostat sounds like. Sit by the furnace (big return air grille) and answer these questions:
1) How long does the furnace blow before it quits?
2) Do you hear a clunk as the gas valve opens?
3) Do you hear a loud click-click-click or snap-snap-snap?