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LP Gas leak


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My 2005 HR Scepter has apparently developed a gas leak this winter.  I live in cold Minnesota, and the coach is in storage here.  I haven't paid much attention to propane levels as I never use much.  Have a residential fridge, so cooktop and furnaces are the only propane consumers.  Tank was pretty full when I put it in storage this fall.  Took the coach for an exercise ride a couple of days ago, and the furnaces wouldn't come on, so I tried the gas stove burners.  Nothing!  Mechanical gauge on tank says completely empty.  Aladdin monitoring system says almost empty, and that system is not very accurate anyway.  So I think I have a gas leak.  Before I put some propane back in the tank and start looking for a leak, I thought I'd ask the Forum for ideas and experiences.  Any ideas, folks?

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Home Depot has a gas sniffer for about $25 that helped me find a leak in my coach. 

Turned out to be the control valve on my water heater (which it sounds like you don’t have)

After thoroughly checking my coach I ended up replacing the regulator (pressure problems) and all of the 15-year-old hoses (preventative). 

The sniffer was key to finding the problem, tho. 

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Almost any propane dealer will check your system for you for free. They won't check your lines but everything attached to your propane tank they'll check to ensure it's working properly. I'd start there and work backwards. You'll have a propane detector installed in the coach, usually on the baseboard below the cooktop. Make sure yours is working properly. They do have a shelf life and if you've never replaced yours in 16 years, it's past it's expiration date. Same goes for the bedroom carbon monoxide detector. Replace it too....good luck...Dennis

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Back about ~6-7 years ago my coach was sitting in the driveway and I'd have to walk by it to leave.  One day I caught a whiff of propane, the next day the same thing.  So I got out a spray bottle of soapy water and fount the 2-stage regulator was leaking.

The original regulator was a Marshal 290 which was obsolete, I was able to find he original spec sheet.   Made a couple calls to RV shops near me, they didn't stock a compatible one.  The original was a 2-stage which allows for higher capacity and helps in higher elevations.  Since I had furnace, fridge, cook top, and water heater I didn't want to take and shortcuts.

I ended up finding a replacement, Marshall Excelsior MEGR-298 Horizontal Two-Stage Propane, on Ebay for ~$26.  I believe there is a parts page in the files for this that I had sent to Fred White to post.




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For anyone this may help. I spent a lot of time reviewing specs and then confirmed with tech support at Marshall Excelsior:

Item 1: As opposed to what you find wind all over the inter webs, The MEGR-295H is NOT the direct replacement for the OEM regulator in a 2006 Diplomat.  Several of the Marshall Excelsior MEGR family of dual stage regulators share the same regulator body, but the EXACT replacement for the OEM regulator is the MEGR-298H (as Jim says above) which does NOT contain the excess flow prevention device.  On Dips (or any other coach with a Manchester LP tank), the excess flow prevention device is part of the POL connector on the pigtail hose that runs from the tank to the regulator.  

Also of note:  the MEGR-298H connection coming from the tank is a 1/4” NPT female.  Many hoses have a 1/4” Flare nut on the end — if yours does be sure you use a ¼” female inverted flare to ¼” NPT male adapter to ensure a gas-tight connection.  Straight NPT threads require pipe dope (or equivalent) for a secure connection; flare connectors do not use pipe dope  

The issue here is that per RVIA code, the excess flow device MUST be at the outlet of the Manchester tank.  If you have a hose from the tank to the regulator with the excess flow device in the regulator, and have a rupture in that hose, the excess flow device will NOT shut off the gas.

Item 2: Also, per the original Monaco design, the pigtail from the tank to the regulator contains the POL connector with excess flow device.  What this means is that other brands of regulator (I.e., Camco, Mr. Heater) may work. I chose to go with the Marshall Excelsior since there is a lot more technical data about them, and I’m a nerd. 😁

One of the things I discovered is that MOST of the “RV” propane hoses (i.e., on eTrailer.com, which has a large selection) do not meet RVIA standards and are NOT RVIA approved.  Does this matter?  You be the judge  

The exact OEM replacement pigtail that runs from the Manchester tank to the regulator for a 2006 Dip is a Marshall Excelsior MER405-15.  The original pigtail is 15” and that length is no longer available, but they do have a MER405-24 (hard to find).  An alternate is a MER401-15 with a ¼” female inverted flare to ¼” NPT male adapter (that’s what I did).

The hose that runs from the output of the regulator to the hard piping in the coach is Marshall Excelsior part number MER611-24 and those are readily available, just not on Amazon  🤷🏻‍♂️

In summary, for a 2006 Diplomat, the exact OEM replacements are:

Regulator: Marshall Excelsior MEGR-298H

Pigtail from tank to reg: Marshall Excelsior MER405-15 (substitute MER401-15 + inverted female flare to 1/4” NPT adapter))

Pigtail from reg to coach piping: Marshall Excelsior MER611-24 (not so hard to find)

I suspect that combination may work in many other Monaco coaches, also.

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