How Do I light My Gas Furnace?

RickO · 09-07-2010, 08:20 PM

We're in southern Minnesota for another few weeks and the nights are starting to get colder. Since we always do our darnedest to be OUT of cool weather, we're learning a few things about our coach. We're also limited to a 20 amp shore hook up at the present time so using the heat pump is out of the question.

The "rear furnace" which I always found to be a bit silly is actually really handy now. The thermostat is located behind the bulkhead door which can be closed to keep just the bedroom/bath warm all night with propane heat.

With the mornings being very cool, I wanted to use the "gas heat" feature on my basement Coleman True Air system. Setting the temp to desired setting and turning to "Gas Heat" results in the fan coming on for 30 seconds and then shutting off. My manual on this system is pathetic and says only to repeat these steps three times and then shut it down and get it serviced.

It sounds like it's just not lighting but I can't find any details on the process from here. Any ideas would be much appreciated.

Thanks,

Rick

Beabop · 09-07-2010, 09:00 PM

Suggest you call Winnebago tech support. They are very helpful.

ichn2go · 09-08-2010, 06:42 AM

First be sure the Propane is turned on at the tank. If it has been turned off, light one of the cook stove burners to start the flow of propane. If this doesn't work call Winnie..Good Luck

TXiceman · 09-08-2010, 07:30 AM

Turn on the valve at the tank and bleed the lines by lighting the stove burners. It may take 2, 3 or 4 attempts to get the furnace to light. The fan normally comes on first to clear the burner section of any trapped gas and then you should hear the igniter popping as it lights. If you can not hear the igniter, you may have a control board issue.

When it shuts down, the burner will shut off and then the fan will run for some time cooling the burner assembly

Ken

RickO · 09-08-2010, 07:59 AM

Thanks all. I've been using propane constantly for hot water, fridge, and the rear propane furnace I mentioned so the valve is turned on. The past couple of days have been so windy that I couldn't even listen for the igniters but today looks better so I'll check it out.

Thanks again....

rick

TXiceman · 09-08-2010, 06:43 PM

Also, some furnaces have another shut off valve at the furnace.

Ken

two-niner · 09-15-2010, 12:41 PM

Here I go again. The Mechanical Code requires a shutoff within three feet.
(arm's length)
Did you find one?

Kerry

RickO · 09-15-2010, 01:56 PM

Ok, I'm feeling a bit silly here because I should know this stuff but I've never had occassion to use the "gas heat" function on my Coleman heat pump before and I'm a bit perplexed.

I've located what I believe to be the gas furnace in a sealed section of my plumbing bay. The "hot" exhaust vent is there. When I turn the thermostat to "gas heat" I can feel cold air blowing out of this vent and I'm pretty sure I can hear the ignightor trying to light it over the noise of the fan. After about 30 seconds of failing to light it shuts down.

I can trace the gas line from the main tank to where it goes into the sealed compartment next to the exhaust fan and there is no shut off valve outside of the compartment. There are at lease 10 Torx fasteners holding the access plate in place and it's even got some weather proofing sealant on it so it's certainly not something they designed for easy, frequent access but I guess removing that is my next step.

Thanks again and stay tuned.

Rick

RickO · 09-17-2010, 02:16 PM

Update:

Well my call to Winnie Svc Admin didn't go as well as I had hoped. In the past, they first ask for my s/n and can address very specific issues with my coach. Today, the tech just asked what the problem was and I explained that my front gas furnace wouldn't light. His response was to tell me that I only had one gas furnace. He eventually pulled the drawings on my coach and confirmed that I in fact have two Suburban gas furnaces.

He went on to explain to me the lighting cycle the unit goes through but that special equipment is needed to test it. His only suggestion was for me to try to start the furnace with the engine running... which I'll try later but.....

During his explanation of what was happening, he told me low batteries could be the problem... but the rear unit works and I told him that specific gravity in all cells is good and my panel reads 13.2v. He dismissed that reading as the charger/inverter and explained that batteries themselves can never read >12.8v(?) I guess I learned something.

But, his last comment really caused me concern. While explaining that my 13.2v reading was coming from the inverter/charger he said I could turn off the Aux Battery switch to take my batteries completly out of service and the coach would still operate normally so long as shore power was connected. Last month I started what became a very long thread on this topic whick culminated in me calling Winnie and getting confirmation that the batteries were in series with the inverter/charger and turning off the Aux Batt switch would cause the entire coach to go black.

So, I'm glad this isn't a major issue and I can wait until November when I return to the area where I purchased to coach to get my dealer to repair it. Upon closer inspection, the only access to the furnace is via an inspection plate which is weather sealed quite tightly and clearly not intended to routine inspection.

Thanks to all for your suggestions and I'll update when my dealer has had a chance to take a look.

Rick

phlemb · 09-17-2010, 04:33 PM

I had the same problem last year , it was too cold for the heat pump so it switch over to the gas furnace. the furnace blower came on for approx 30 sec , tired to ignite but then shut down, after $350. it came down to a faulty sail switch (micro switch) it wasn't sending a "blower working" signal back to the board therefore shutting it all down. replaced switch, now all is good. hope this help

06 35a itasca sunrise

Beabop · 09-17-2010, 07:17 PM

WOW, he told you everything would work with the aux off. Should have gotten his name. Our 12 V was off last week, frige of course wouldn't work . I called Al at Winnie, told him no tripped breakers. He said could your aux bat switch be off? Well someone had bumped it and with it on ,all was right with the world.

RickO · 09-17-2010, 07:35 PM

Quote:

Originally Posted by phlemb

I had the same problem last year , it was too cold for the heat pump so it switch over to the gas furnace. the furnace blower came on for approx 30 sec , tired to ignite but then shut down, after $350. it came down to a faulty sail switch (micro switch) it wasn't sending a "blower working" signal back to the board therefore shutting it all down. replaced switch, now all is good. hope this help

06 35a itasca sunrise

He did mention the sail switch. I trust my ext wty will cover this and I think we'll be ok until I can get my dealer to look at it. Especially considering the coach is nearly 4 years old and I've never used it!

Quote:

Originally Posted by Beabop

WOW, he told you everything would work with the aux off. Should have gotten his name. Our 12 V was off last week, frige of course wouldn't work . I called Al at Winnie, told him no tripped breakers. He said could your aux bat switch be off? Well someone had bumped it and with it on ,all was right with the world.

Yep, he sure did but at that point I had lost all confidence in what he had to say and just wanted to get off the phone. He was polite and friendly but was clearly shocked (not surprised) that I actually had two Suburban furnaces. It was kind of downhill from there. I can't be sure but I think his name was Tom.

Good man · 09-17-2010, 08:06 PM

RickO,

Most any LP gas distributor will perform a courtesy safety check to determine if something needs attention. It is good business for them to promote the safety and reliability of LP gas. During this process, they will often successfully light the appliance.

You can also safely do certain things, as long as you do not defeat any safety controls.

Assuming that you have fuel in the tank, have a working gas leak detector which is allowing the gas to leave the tank, assuming that you have lit a gas burner on the stove to clear the lines and prove the emergency shut off is open, then,

During the follow procedure, leave storage bay doors open, the coach door open and several windows open to prevent the build up of gas. Have no engines running... neither the genset nor the MH engine. This almost certainly eliminates the potential for a flashover.

If you can look at the combustion chamber area of the furnace and locate the electric spark starter, you can verify whether it is sparking when the gas heat is demanded. This starter has an electrode in the area where the fuel enters the combustion chamber and it has an insulated, very flexible wire leading back to a valve mounted on the fuel line. This valve has wires leading back to the control module.

When the gas heat is demanded, if you do not hear loud repeated clicking and observe this spark, your control module, or other components may not be working. The is no harm in sharply bumping the control box with a closed fist to encourage it to signal the spark. Wait about 2 minutes between attempts to allow any fuel to dissipate.

You can repeat this process as many times as you like as long as you do not detect the smell of LP gas. This may clear any air out of the line leading to the furnace and eventually result in the furnace igniting.
Hope this helps... Be Careful.
Jim

RVhauler · 09-17-2010, 08:13 PM

If the electrical voltage is not sufficent then the fan will not turn fast enough and in turn prevent lighting of the furnace (ie: fore mentioned sail switch)

RickO · 09-17-2010, 08:22 PM

Thanks much Jim. All the basics you mentioned are in order since we're using gas to power our fridge, water heater, and stove regularly. The biggest problem in troubleshooting this further is it's lack of accessability. It is weather sealed behind a substantial plate which I don't want to pry off unless I have to. Therefore, I can only see what is visible trhough the exhaust openings... which by the way have had mud dauber screens on them since coach delivery.

When I put the thermostat in a gas demand mode the purge fan runs for 30 seconds but then shuts down. I can detect no sound coming from the igniter. I have repeated this process no fewer than 20 times.

The control box you refer to, is that the Tru Temp thermostat or is this something located on each gas furnace?

BTW, I appreciate you concern for safety and find it ironic that the only real suggestion the Winnie tech had for me was to try lighting it with the engine running.

Rick

RickO · 09-17-2010, 08:26 PM

Quote:

Originally Posted by RVhauler

If the electrical voltage is not sufficent then the fan will not turn fast enough and in turn prevent lighting of the furnace (ie: fore mentioned sail switch)

Thanks. Actually the Winnie tech did explain this quite well but the batteries are all less than a year old, test fine and the rear Suburban gas furnace lights just fine so this is probably a long shot in this case.

Rick

Good man · 09-17-2010, 08:28 PM

Quote:

Originally Posted by RVhauler

If the electrical voltage is not sufficent then the fan will not turn fast enough and in turn prevent lighting of the furnace (ie: fore mentioned sail switch)

Thanks! and I absolutely agree RVhauler... that is why I said:
When the gas heat is demanded, if you do not hear loud repeated clicking and observe this spark, your control module, or other components may not be working.
What I think the procedure I outlined will reveal is that he is not getting ignition spark... then we can start ruling out why.

What he had said already is that the other furnace works fine. This tells me he has adequate voltage from the batteries and it is specific to the ignition and control on this furnace ...including a faulty sail switch.

I appreciate the feedback and I certainly do not want to advise anything to place anyone in danger... so if there is anything questionable here, let's be sure it is made known.

Sincerely,
Jim

Good man · 09-17-2010, 08:44 PM

Quote:

Originally Posted by RickO

Thanks much Jim. All the basics you mentioned are in order since we're using gas to power our fridge, water heater, and stove regularly. The biggest problem in troubleshooting this further is it's lack of accessability. It is weather sealed behind a substantial plate which I don't want to pry off unless I have to. Therefore, I can only see what is visible trhough the exhaust openings... which by the way have had mud dauber screens on them since coach delivery.

When I put the thermostat in a gas demand mode the purge fan runs for 30 seconds but then shuts down. I can detect no sound coming from the igniter. I have repeated this process no fewer than 20 times.

The control box you refer to, is that the Tru Temp thermostat or is this something located on each gas furnace?

BTW, I appreciate you concern for safety and find it ironic that the only real suggestion the Winnie tech had for me was to try lighting it with the engine running.

Rick

You bet Rick! ... SAFETY FIRST! The Winnie tech did not really do anything wrong, he was just assuming that everything was up to specification and he wanted to be sure the voltage was up enough to spin the fan fast enough for the sail switch... just like RVhauler stated.

Without tearing into the unit, if you are not hearing an igniter, you can locate a box (probably plastic) attached with wires connected to it on the steel box surrounding the furnace. This is where you can apply the closed fist "adjustment" within reason. Also, check the wires for good connection.

I doubt there is any problem at the TruTemp thermostat, since it is in fact sending a demand at a given set point.

Just bump around lightly on the control box and tap lightly with the butt of a screwdriver on any valve with wires, making sure the wires are making good connection.

If you have a large LP gas distributor in your area, call them and ask them if they will assist you in lighting your furnace. I would be very surprised if they said they would not do it. As I said, it is good business for them to not have gas appliances malfunctioning.

If there is a charge for inspecting the system, have them look at everything... it will probably cost the same. Then you will peace of mind.

Please continue to work safely if you proceed with this on your own.
All the best,
Jim

KennethM · 09-18-2010, 04:07 PM

RickO, Good Man is right on with the sail switch is probably just stuck from sitting in the normaly open position for 4 years!!!! The circuit is as follows the thermostat calls for heat then the fan starts and the sail switch has about 30 seconds to close the normally open contact then on to high limit normally closed contact and back to circuit board okay to try and light gas. Flame sensor/spark probe will verify flame in furnace and all is good to go with this being a short version of the process. Common problems with the suburban funace is low voltage, dirty edge connector on circuit board, stuck sail switch and loose automotive push on connectors at above connections. All of this is easly accessed behind that sealed panel that is a "Bear" to get off if the 2 tubes from the intake/exhaust are not rusted too badly. I have helped a friend with his furnace and it lasted a couple of more years until the main circuit board failed then he had a mobile rv replace the board.

two-niner · 09-18-2010, 05:51 PM

There must have been changes made on the furnaces. The one place has no connection at all to the rear heater on the 08 Tour.
It works on the thermostat on the bedroom wall ONLY. Try turning your one place off, go to bedroom and turn the thermostat all the way up. You should feel the switch in the thermostat setting lever. It takes about 15 seconds to start blowing (cold air at first, then warm, then hot).
Mine will blast hot air in the bathroom as well. It never has to be run for more than 5 minutes, then I turn it all the way off. It will run if the main furnace is also working.
Let us know.

Kerry