furnace issues - LP Regulator??

[scesarini]

I replaced my two furnaces in my 1988 Airstream 345 and having a hard time getting them to work properly. It’s freezing and I need to figure it out asap.

the furnace starts and than immediately turns off. the tank has gas. Is it possible the regulator which has never been replaced is not providing enough LP to the furnace? What is the replacement for my regulator? Where do I find?

Also the valve for the tank has a slight leak, was thinking of sealing with some silicon or wax?

Really appreciate any help.

[Wazbro]

It is possible the regulator isn't letting enough propane through, I have no idea what regulator for a motor home. Could also be a buildup of the additive in the propane that provides the odor in the lines blocking the lines. Do other propane appliances work well?


I would not bet my life or anyone else's life on sealing a propane leak with some silicon or wax. If it is a valve you can remove and put some gas rated Teflon tape on I would do that, unfortunately the tank would need to be empty to do that.

[richard5933]

If there is a proper propane dealer near you take the motorhome there. The regulator should be replaced with a new 2-stage regulator.... It will be the same as is used in a trailer but might need fittings to get it installed in your setup.

The leak? Do not attempt a DIY repair like you're describing. Just don't. We don't want to read about a fire or worse resulting from this.

The propane dealer can empty the tank and then replace the leaking valve. They're not expensive and well worth getting replaced professionally. I don't mean to be offensive here, but if you're considering sealing it with silicone or wax it sounds like you'd benefit from having them replace it for you. There are reasons motor homes have propane fires,, and leaky valves is one of them.

[BikeCamper]

Let me also add that it would be smart to have a professional check your work on the new furnaces you installed, and run a pressure test on your propane system. The pressure test should be conducted after the known leaks are corrected.

[Redbarron55]

The furnace has a flame detector thermistor that lets the board know that the flame is lit and if that signal is too weak the gas valve will shut off.
There could be a bad sensor or it may not be located where the flame touches it correctly.
This is what I would suspect first.

[uncle_bob]

Hi

+1 on the cautions on the regulator and leaks. They are *NOT* something you can just ignore. You very much need to go visit a pro for this part.

Assuming we're past that part:

If you have a propane stove, light that up. Do you get a nice blue flame? Can you adjust it over the full range (from really low to really high)? Does it keep burning for at least 10 minutes?

Assuming the answer to all that is yes, then you do have propane running here and there.

Now repeat the test with the stove and turn on the furnace while the stove is doing it's thing.

Does the stove go out?

Assuming it doesn't, there is no supply issue on the propane side. The issue is the furnace and that part needs to be debugged. As noted above, there are various sensors that need to be hooked up and working. There are also air passages that need to be clear. Just which one *is* the issue ... who knows.

Fun !!!

Bob

[Wetfeet]

The furnace not lighting sounds like the sail switch is bad, or maybe just needs to be adjusted. The sail switch must be “open” when the furnace starts, and then when the fan gets going the flow of air pushes on the sail switch and the switch is then supposed to “make”. Sometimes the contacts on the sail switch get corroded with time, and the only way to fix that is with a new sail switch. You can check for corroded contacts using an ohm meter (DVM). Sometimes the little “sail” can get bent from bouncing down the road, and a simple adjustment might fix it. Two small screws and you can remove the sail switch for inspection and/or replacement.

A gas leak near your tank valve is most likely coming from the hoses that connect the tank valve to the regulator. The hoses have small rubber seals at the joints that dry rot and start leaking a tiny bit of gas over time. I have to replace my flex hoses about every 4-5 years for this reason. A small gas leak will not prevent the furnace from lighting, but it is unsafe!

[Rick n Mary]

Originally Posted by Wazbro

It is possible the regulator isn't letting enough propane through, I have no idea what regulator for a motor home. Could also be a buildup of the additive in the propane that provides the odor in the lines blocking the lines. Do other propane appliances work well?


I would not bet my life or anyone else's life on sealing a propane leak with some silicon or wax. If it is a valve you can remove and put some gas rated Teflon tape on I would do that, unfortunately the tank would need to be empty to do that.

I wouldn’t bet my life on it either!!!!
With the age of the vehicle, and the picture you posted, replace it!
I recently saw a news article about an RV fire next to a home in Manassas VA….. RV and house GONE
Please replace it, don’t be a statistic!

Your bottle should have connections that will unbolt. If you can’t do it find someone who can. I replaced my hoses from bottle to regulator and regulator to trailer, relatively simple….. I’m not familiar with your airstream, but it shouldn’t be that difficult!
Rick.

[Wetfeet]

I forgot to mention that if the exhaust outlet on the furnace gets disconnected from the extension pipe (tailpipe) that connects to the outside, then the furnace might light but will quickly go out again. A friend had his factory installed furnace do this after many years of service. The factory neglected to fasten the furnace to the board it sat on, so over time bouncing down the road caused the furnace to shift and the pipes separated. The tailpipe must remain inserted into the exhaust outlet on the back of the furnace, otherwise exhaust fumes will quickly extinguish the flame. Atwood calls for a minimum insertion of at least an inch or more.

[Skyhook]

We had the same issue in our 2019 flying cloud. The tech at Jackson Center found the issue. There is a little wind vane flapper valve in the blower If that is clogged or malfunctions the burner will shut off. Ours was clogged with some cat hair. The furnace sucks air off the floor under the sink. After clearing the clog it worked fine. Search YouTube for the issue to see removal and replace etc

[bolerama]

I agree with what Wetfeet and Skyhook wrote regarding the sail switch (like a little wind vane). While we were in freezing weather in Bryce Canyon, Utah, our sail switch went, and we couldn't get a replacement until we were in Arizona. Unfortunately, Dometic/Suburban no longer make them, so you have to get an inferior one. We paid $40 for an inferior one and it lasted 3 days, so we returned it to the RV shop. The next replacement also lasted about 3 days. (Online, this is a common complaint.) My advice is to buy several cheap knock-offs on Amazon (The one with the number code that ends in MC seemed to have the best reviews). The new ones don't last long, and you don't want to be caught in sub-freezing weather without back-up switches.

[lemley]

+1 on propane tank valve. Mine started leaking Friday after a refill. I’ll be taking it in next week.

I have an 88 Excella. My second. I’ve done a lot of fighting with the furnaces. I was able to keep them going until the fan motors went out. I ended up replacing them.

There are several things that can cause the symptoms that you describe. This thread has a detailed description of how the furnace startup works.

https://www.airforums.com/forums/f42...-228923-2.html

Some of the probable causes:
1. No propane pressure
2. Sail switch
3. Propane solenoid in the furnace
4. Furnace internal wiring issue
5. Bad control board.
6. Fan motor

Did you say that you replaced two furnaces? Are they both showing the same symptoms? Are the replacement furnaces new?

If you have two furnaces, both of which are not working, then it sounds like you are not getting propane to the furnaces. If that is the case, I would start by replacing the propane alarm. They are spec’d for 7 years and you are literally playing with fire. Safety first. Next I’d check the stove. Does it work? If not, check tank, valve and regulator. If the stove works, I’d next do a pressure test.

[Steamy1]

Something else to consider is the possibility of deterioration of the pigtails connecting the tank to the regulator.

I recently was having issues with the furnace and refrigerator running properly. I disconnected the pigtail from the regulator and discovered small pieces of rubber lodged in the regulator. The existing pigtails were replaced three years ago with Sturgis stainless braided ones. So not that old.

I not only replaced the pigtails, but also the regulator and hose from the regulator to the copper fitting.

All appliances work now.

[Wazbro]

Originally Posted by Steamy1

Something else to consider is the possibility of deterioration of the pigtails connecting the tank to the regulator.

I recently was having issues with the furnace and refrigerator running properly. I disconnected the pigtail from the regulator and discovered small pieces of rubber lodged in the regulator. The existing pigtails were replaced three years ago with Sturgis stainless braided ones. So not that old.

I not only replaced the pigtails, but also the regulator and hose from the regulator to the copper fitting.

All appliances work now.

That is not something to consider on a Motor Home, just 1 built in tank not 2 portable cylinders like a trailer.

[scesarini]

appreciate your reply, where is the propane alarm? I didn’t even know I had one of those…

[Wazbro]

Originally Posted by scesarini

appreciate your reply, where is the propane alarm? I didn’t even know I had one of those…

You may not have a propane alarm, I'm pretty sure they were not standard before the 90's, maybe not till the 2000's.

Anyway, you should have one inside near the floor somewhere (not where the dog sleeps though).

[richard5933]

Originally Posted by Wazbro

You may not have a propane alarm, I'm pretty sure they were not standard before the 90's, maybe not till the 2000's.

Anyway, you should have one inside near the floor somewhere (not where the dog sleeps though).

Our 1994 has one, so at least since then. They are usually located down towards the floor somewhere on one of the interior walls.

[uncle_bob]

Originally Posted by Wazbro

You may not have a propane alarm, I'm pretty sure they were not standard before the 90's, maybe not till the 2000's.

Anyway, you should have one inside near the floor somewhere (not where the dog sleeps though).

Hi

..... also don't mount where the "test" button is easily bumped as you walk by the device. No fun for the rest of the crew when you do that at 3AM. I have an unfortunately large amount of empirical data to support that claim.

You can only blame that alarm on the dog a finite number of times .

Bob

[lemley]

Both of my 1988 trailers had alarms. They were mounted to the cabinet next to the furnace. Both were black.

They looked like this but were black.

https://johnsonssurplus.com/products...RoCQf8QAvD_BwE

[Bill M.]

I had a furnace issue like that on my trailer. Had a pro come work on it. He found the gas flow to be too low. He changed the regulator. The flow was still too low. He then found that the rubber hose connecting the regulator and the copper lines in the trailer had deteriorated inside and was partially blocked. Changed that line and it worked. I think you need a flow gauge or professional help.