Furnace Help

Benny · 10-04-2020, 02:08 PM

I have an ‘03 E350 7.3l diesel and am trying to get my furnace working. Just had a new thermostat installed and the blower is working fine. It’s got the Suburban furnace but it does not ever blow warm air. FYI When I put on the Starcraft AC it blows cold.

I’ve followed the owners manual steps of propane turned off, turn thermostat to low and then 5 mins later, turn on propane and increase the temp on the thermostat but the air it blows never warms up.

Any suggestions? I’ve only owned the rig for 5 mo so it could be a very simple user error! TIA

REF · 10-05-2020, 04:53 AM

Never seen those directions you are following from the manual, I always had my propane valve open before setting the thermostat temp for heat. The heaters have their own control board and the initial startup goes through the sequence of spooling the blower to clear the combustion chamber of any unburned gasses before flowing gas and igniting. Your issue may simply be that there’s just no gas available during this initial startup process and the unit never fires, although I thought that it would continue to try until there is fuel available and ignites?
Do you hear the clicking? That would be the igniter, if not, you’ve got a problem there or with the built in valve on the heater, but I’d try opening your propane first and see if it fires up.
Here’s some more info....

https://www.rvtravel.com/troubleshoo...nace-problems/

arctictraveller · 10-06-2020, 11:40 PM

It’s common that it takes numerous start attempts due to air in the line from sitting. You can loosen the propane line at the furnace to bleed out the air, but do it in a well ventilated space and once you smell propane, tighten the fittings and let the fumes clear out for several minutes before trying to start it again.

Benny · 10-07-2020, 06:44 AM

Quote:

Originally Posted by REF

Never seen those directions you are following from the manual, I always had my propane valve open before setting the thermostat temp for heat. The heaters have their own control board and the initial startup goes through the sequence of spooling the blower to clear the combustion chamber of any unburned gasses before flowing gas and igniting. Your issue may simply be that there’s just no gas available during this initial startup process and the unit never fires, although I thought that it would continue to try until there is fuel available and ignites?
Do you hear the clicking? That would be the igniter, if not, you’ve got a problem there or with the built in valve on the heater, but I’d try opening your propane first and see if it fires up.
Here’s some more info....

https://www.rvtravel.com/troubleshoo...nace-problems/

Thanks for the feedback. I tried opening the valve first but still no heat. I did not hear any clicking.

Should I be doing anything with the switch that turns on the AC? Once that is on, I can adjust the blower speed to low med hi

REF · 10-07-2020, 08:13 AM

It might be that you need to bleed the line as Arctictraveller mentioned. You also mentioned a new thermostat was installed.....did the heater work before with the old thermostat? And who installed the new one? I would check the connections on the back.
And while your new thermostat might have hi/med/low blower controls, don’t think the suburban has a variable blower motor.
Also, keep in mind that you can’t use a typical home thermostat in an RV, you need one that is rated for a 12V system, and one that has a battery, which I believe would be used to send the signal for the igniter.
I upgraded to a digital thermostat that had batteries when I had the suburban and it worked great at holding the temps within a few degrees vs. the old mercury switch that had a much bigger temp swing. I think I was able to find it at my local hardware store.

Ben10281 · 10-07-2020, 08:50 AM

Here is the process that I normally follow with my Suburban heater.(NT-12SE)

1) Turn on propane at the tank
2) Switch Thermostat to "on"(I have the old analog mercury style thermostat)
3) Set temp on Thermostat
5) Suburban then starts the fan
6) When the fan is up to speed it activates a sail switch which in turn activates the igniter and also must activate the flow of propane
6) Rapid audible clicking is heard, this is the igniter sparking
7) Clicking stops once the propane burner tube has lit
8) Hot air starts emanating from the heater.

If you are not hearing the clicking(it is loud enough that I can hear it while standing just about anywhere in my van) then it is likely that your igniter is not sparking at all. If it is not sparking, then you will never light the propane and will never produce heat. There is a sight glass on the front of my heater that you can look through and see the spark of the igniter and, once lit, the actual blue flame coming from the propane burner tube. I would get down and watch through this site glass to see if you are seeing any sparks/flames once your fan kicks on.

arctictraveller · 10-07-2020, 04:19 PM

Scroll down to page 30 for a troubleshooting guide

https://manuals.heartlandowners.org/...11-05-2015.pdf

photographix · 10-11-2020, 12:00 PM

My Suburban furnace failed to start because the sail switch was having intermittent failures. It is typically the first thing to check, and the cheapest to replace.

racer_rr · 10-11-2020, 12:31 PM

Fuel + spark = fire.
My furnace problem was the pressure regulator at the tank was gunked up and not releasing sufficient propane for the furnace, especially at altitude.

lolo · 10-11-2020, 01:13 PM

I just went through the furnace problems on a 2004 12000 BTU Surburban furnace. It seems the two most likely problems are low voltage to the furnace and low gas pressure from the regulator. Low voltage to the fan may not turn the fan fast enough to engage the sail switch. Low gas pressure from the regulator may also cause the burner not to light. Follow the procedure listed in the troubleshooting section of the manual. https://manuals.heartlandowners.org/...11-05-2015.pdf

I eventually replaced the 12000 BTU core with a 15000 BTU core which fit into the same housing.