Furnace problems HELP

[ChaseM]

That model you quoted is for a 40,000 BTU furnace, but I have only known Keystone to use the 35,000 BTU even in the High Country. Have you confirmed the actual model of yours from the tag on the unit?

Yes this is the sticker

 

[firestation12]

I forgot to mention in post #12 that I believe it is the negative wire going to the gas valve (from the control board), that the control board uses to sense the milli-volt passing through the burner flame. CK the connection of that wire at both ends.

 

[ChaseM]

Update, yesterday I was able to pull almost every piece of the furnace apart and clean/dust off. Reconnect connections and ensure good connections. Check the sail switch made sure it’s not hitting the housing or blower blades. Worked for about 5 hours through the night then it continuously would ignite or try to ignite and run for about 5-15 seconds then stop. Then repeat the cycle, blower never turned off which is good because previously it would just fault and the blower would never kick on again. Sail switch issue?

 

[jsb5717]

Update, yesterday I was able to pull almost every piece of the furnace apart and clean/dust off. Reconnect connections and ensure good connections. Check the sail switch made sure it’s not hitting the housing or blower blades. Worked for about 5 hours through the night then it continuously would ignite or try to ignite and run for about 5-15 seconds then stop. Then repeat the cycle, blower never turned off which is good because previously it would just fault and the blower would never kick on again. Sail switch issue?

Go back to my previous post. Have you replaced the regulator yet?

 

[ChaseM]

Go back to my previous post. Have you replaced the regulator yet?

Are you referring to the regulator at the propane tanks or the regulator at the furnace itself? I did replace the one at the propane tanks with a JR Products 07-31525 Low Pressure 2 Stage Regulator, says it’s rated for 262,500 BTU’s.

 

[jsb5717]

How long ago did you replace it? I don't know how that one compares to the Marshall Excelsior...I just know the ME works to provide the propane flow required by the Furnace.

https://www.ebay.com/itm/1868831193...q7G/mkR/VshFXPpYwLT6bURuw=|tkp:Bk9SR5Kmiv2NZQ

I can't guarantee that this will solve your issue. But I know that on one occasion our furnace failed (twice on our friends furnace) with the exact same symptoms and the regulator was the culprit. I also know by experience that those symptoms can be caused by a rusted over or blown out diffuser/burner.

 

[jsb5717]

I read your original post again and see that you did replace the regulator at the beginning of your issues. I haven't dug into the specs of the JR but if it's rated for RV use then it should work. For an RV the regulator needs to provide a flow rate of 11 column inches of water. Most of us don't have the equipment required to test that so it's challenging.

It can be frustrating to chase gremlins by throwing new parts at the issue. But after our 2nd furnace failure I made the decision to buy and carry every conceivable replacement part so I could easily troubleshoot and not get caught without heat in cold weather. It made repairing our 3rd failure pretty easy.

There are some pretty knowledgeable guys on this thread all with good troubleshooting ideas so you're looking at a lot of potential causes.

In my mind there are a few things that could cause those failures and you've looked at several of them. It's hard for me to imagine that it's the sail switch since it is firing. I've never seen one fail after ignition...but maybe.

Some will say that the Limit Switch either works or it doesn't. I'm of the school of thought that it can get weak and allow ignition but then shut off the furnace prematurely even though the temp isn't at a risky level.

The main control board can have a glitch, even though that seems less likely

The propane valve attached to the diffuser/burner might be under-performing. This one also happened on a friend's furnace

A loose or corroded connection can be a culprit.

Anyway, all of these are pretty easy to check if you happen to have all of the parts on hand.

Our first furnace failure occurred, like you, when our trailer was still fairly new but out of warranty.

 

[ChaseM]

Thanks for the advice. I’m about at the same point, there’s a lot of good possibilities but with the symptoms changing now it has me looking at so many things. Also makes it hard when it’s too warm to run for hours during the day (I’m in Arizona right now). So I kick it on for the night and I’m not going to go outside and troubleshoot at 3am when it’s cutting off. I think I’m going to try a limit switch again because that was a culprit at first. From there the gas valve/regulator would be my next guess. But a limit switch that opened wouldn’t let it try and ignite constantly? So I guess gas valve could be gunked up or gone bad. Or regulator change again.

 

[ChaseM]

Correction, I just re-read your idea of the limit switch weakening! Also I have been under the impression that the regulator could have been the issue for awhile now even after replacing. Especially cause the very first problems occurred when hooked up to a big propane tank from a 3rd party and I could turn all the gas off and re open valves slowly to fix the heat for awhile. So that makes me wonder if the one I replaced it with is flawed or not rated.

 

[NH_Bulldog]

Are you referring to the regulator at the propane tanks or the regulator at the furnace itself? I did replace the one at the propane tanks with a JR Products 07-31525 Low Pressure 2 Stage Regulator, says it’s rated for 262,500 BTU’s.

I think your regulator is undersized.

When I replaced the regulator in my Passport travel trailer for the recall a few years ago, the exact replacement for mine was 345,200 BTU. I can't imagine smaller is better in this case.

 

[jsb5717]

I think your regulator is undersized.

When I replaced the regulator in my Passport travel trailer for the recall a few years ago, the exact replacement for mine was 345,200 BTU. I can't imagine smaller is better in this case.

And the more I think about it a High Pressure regulator should be preferable...especially for the furnace.

 

[JRTJH]

And the more I think about it a High Pressure regulator should be preferable...especially for the furnace.

The pressure output from the regulator MUST remain the same or you risk the other propane appliances in the trailer not working properly....

I'm sure you meant "High Output Regulator" which would provide the required propane output to operate "the demand placed on the regulator" (VOLUME) by more than one appliance drawing gas at the same time, but the pressure in the trailer propane system MUST remain constant...

Furnace LP input: 40K BTU

Stovetop burner input 5K BTU or 8K BTU Total averages 18K BTU with all in use
Oven Input: 11K BTU

Tank water heater: 18K BTU

Tankless water heater: 42K BTU or greater, depending on the water heater.

Outdoor kitchen: usually 5K BTU per burner

Outdoor propane quick disconnect: Demand varies based on appliance connected:

Propane generator: Demand varies and may have its own regulator, but if connected to the trailer primary regulator affects demand on the regulator.

 

[ChaseM]

I do agree it could be undersized. When I ordered my replacement I bought the same exact looking model but did not realize it was a smaller version. Though no other appliances should be running at night with the heater currently, water heater is electric. Maybe the fridge but that would be it.

 

[jsb5717]

John, as usual you explained it better. Yes, that's what I meant. I know that Marshall Excelsior has both a 253H and 253HP model. The HP, which is what I currently am using, is supposed to support more appliances while maintaining the requisite pressure. The H model should work just fine for most of our rigs with the standard mix of appliances. I don't have an on-demand water heater (nor do I want one) but I can imagine that including that device may need the HP over the H.

In any event, without knowing the output specs on the OP's JR regulator it's hard to say if it's up to the task or not. My hunch is No.

An eBay search for the 253HP version yields some pretty good buying opportunities.

 

[ChaseM]

Thanks guys. These are the specs on the one I used to replace it. I guess it could still be undersized even though it’s usually the furnace usually runs by itself at night. Gonna go with limit switch, burner/gas valve, and a regulator as my most possible issues as of right now. Have it running just continues igniting for 10 seconds at a time.

 

[sourdough]

Here is a link to the Marshall Excelsior regulators;

https://www.marshallexcelsior.com/2-stage-excela-flo-auto-change-over-regulator-14-inv-x-38-fpt

I replaced my OE Fairview with the 253H - a very positive change. I also replaced the high pressure regulator on the off side;

https://www.rvupgradestore.com/Exce...VQFJ_AB0JUCdoEAQYAyABEgLcd_D_BwE&gad_source=1

I was having some LP issues with flow etc. that I couldn't pinpoint. When I pulled that high pressure regulator it was filled with oil and dripped oil for days. Took the tanks and had them purged and the issues disappeared. HP regulator, dual stage, oil in LP tanks or all 3? I wills say that I am not impressed with Fairview and have no experience with the Panther product but Marshall Excelsior is pretty much top of the line IMO. Note the output difference between the Panther and 253H.

 

[JRTJH]

This post is for "clarity" in part numbers, and is not intended to criticize anyone...

i did some more "digging around the Marshall website and found that there is no Marshall regulator part number MEGR-253HP.

The "standard Marshall regulator commonly used in RV's is the MEGR-253. The "high output version" of that same regulator is the MEGR-253H.

I realize there are numerous EBay "merchants" that are selling the "Marshall MEGR-253HP regulator"... We recently had a thread about a WFCO converter/charger on Amazon that was determined to be a "counterfeit knockoff" and not actually a WFCO product. I can not say for sure, but I wonder if some of the EBAY MEGR-253HP regulators are really MEGR-253 regulators, some of them are really MEGR-253H regulators and some of them may be "something else entirely, not even produced by Marshall, but somewhere in china and being sold on EBay as a MEGR-253HP (which is not even a Marshall part number) ?????

I am not criticizing EBay, but as we found with Amazon, not everything being sold there is what it's represented to be... Could this be a case where someone is selling MEGR-253HP regulators because they are NOT representing them as a "factual Marshall part number" ???? Or maybe just selling a knockoff (or maybe the real thing) using a similar part number...

Anyway,

The OP's replacement JR regulator with an output of 262.5K BTU is greater than the Marshall MEGR-253, so it should work in his trailer, especially if only the furnace is drawing propane from the regulator. And, based on his comment about his gas refrigerator, the BTU requirement for the refrigerator burner is 400BTU input, so the refrigerator uses an almost negligible amount of propane, certainly not enough to affect the furnace operation with either regulator output.

If you go to the Marshall website, there is a pdf available that compares the two. The link for that pdf is: https://www.marshallexcelsior.com/2-stage-excela-flo-auto-change-over-regulator-14-inv-x-38-fpt

The MEGR-253 output is 225K BTU
The MEGR-253H output is 350K BTU

Doing a search on the Marshall website, using their search engine for the term "MEGR-253HP" produces a result of "Your search returned no result".

Here is a screen shot from the Marshall website showing the search results:

 

[ChaseM]

That’s good to know JRT thanks. I will focus on that last. The regulator I bought was on the cheaper end and off Amazon but not gonna rule that out yet. I know I’ve been all over the place and now I have new symptoms with the furnace, but is limit switch and burner/valve assembly good place to start with furnace constantly igniting and going out?

 

[jsb5717]

Have you checked your fuse? Is it black? If so then it's resettable and should be replaced with a standard blue 15a fuse.

 

[ChaseM]

Have you checked your fuse? Is it black? If so then it's resettable and should be replaced with a standard blue 15a fuse.

I believe it is black. I’m not home right now. Why should it be replaced? So I know when it’s blowing a fuse? Only a short would blow the fuse correct? Limit switch will trip and valve will close in other scenarios of malfunction.