Furnace main burner doesn't light

[TRICUMBENT]

Sent: 3/24/2002

Shirley and I recently purchased a 1975 Winnebago Brave. It needs a little "fixin' and TLC." The space heater is my next project. The space heater is a Coleman, Model number 4023A, BTU rating of 17,250. I do not know whether this is the unit that came with the Brave.

I can light the pilot flame (from the 12V glow plug or with a match). The pilot will stay lit. The blower will come on (when the thermostat "demands" heat).

The problem is that the main burner does not light. The main valve, that supplies propane to the burner, is not activated.

Any suggestions would be greatly appreciated.

Jim

[Elandan2]

Sent: 3/25/2002

Hi Jim,

On my Winnie I found that there was a bad connection on the plug to the right of the gas valve.  I simply disconnected the plug (there is a locking tab) and cleaned the terminals.  After that the furnace operated fine.  Hope this helps.

Rick

[chip]

Sent: 3/26/2002

probably need a new limit switch. I'd also clean the rust out of the burner ports and throw in a new sail switch. try 800-258-3078. I'm not sure they will sell direct but they'll give you good info and tell you where to buy the parts.

[MSN Member]

From: TRICUMBENT   
Sent: 5/6/2002

I wanted to thank everyone who wrote to me. All of the advise was excellent. The heater is working fine now.

Troubling shooting the unit was a learning experience. I now have 20-20 hindsight! Since everyone was so helpful to me, I thought that I would pass on my learning experience to all of the folks on this list.

The following is the short version of troubleshooting this problem. If you need more information, contact me off line.

After getting the pilot light lit and with the thermostat demanding heat, I measured the voltage to the main gas valve solenoid coil. It was only 9.7 volts. The voltage at the coach battery measured 12.7 volts (a loss of three volts!)

Since I have a variable DC power supply, with built-in volt and amperage meters (I know, I have too many tools), I directly powered the heater unit from the DC power supply (I completely bypassed the coach power system). What I learned is that the unit must have a minimum of 10 volts to open the main gas solenoid and the unit drew about 6 amps when running. Once I delivered the threshold voltage to the unit, it worked just fine.

Since the thermostat was old and looking a bit corroded, I replaced it. Also, I only had one coach battery. After doing some research in the archives that this group so graciously makes available to everyone, I realized that I needed two coach batteries (now I know why the battery tray is so large - Daahh!).

Anyway, after installing the new thermostat and another coach battery (with both batteries fully charged), the heater works great. I will be ready for next winter.

Thanks again everyone. I hope that this will help someone out there with heater problems.

Jim