LP System Questions

[NRALIFR]

I’d noticed the fridge performance on LP had dropped off lately, so I started doing all the usual checks and maintenance. Cleaned the burner, LP orifice and flue, checked the flame and it looked ok, but I noted that I couldn’t “hear” the flame noise like I remembered. Normally if it’s quiet enough, I can hear the flame without even opening the lower access panel.

I decided to order a Digital Manometer to check the LP pressure. When it came in I tried to remove the test port plug from the fridge solenoid valve body and found that it was stuck permanently. I cranked on it as hard as I dared but it wouldn’t budge. I checked the price of a new valve to help me decide if I wanted to break it trying to get the plug out. $150 for a new one, so........ nope. That plug is staying there.



After looking around a while, I found another test port on the LP generator I could use. I just have to hold the Prime button down to get the LP to flow to the port location. After removing the plug, before I attached the manometer I pushed the Prime button on the generator just to make sure the LP would flow, and I heard a faint gurgling sound coming from the test port. I knew what that meant: there was most likely that black stinky liquid in the LP line low points impeding the flow of LP. I went ahead and checked the pressure with the fridge running in LP mode, and sure enough it was low. About 7.5”h2o



The first low point on my TC is at the bottom of the regulator. I removed the hose, and sure enough, a good amount came out. The regulator also showed signs of the liquid seeping out of its seams and weep holes. I cleaned the regulator up as best I could, but I was having trouble adjusting the pressure up to 11”h2o, so I’ve also ordered a new one. I got the pressure up there, but the adjuster is screwed all the way in. I can now hear the flame on the fridge again and it’s cooling better. :B



When the regulator is in it’s normal orientation, any liquid in the LP line should collect in the low point below the regulator and not get beyond it. Unfortunately, when you have to remove one of the cylinders for filling, you have to swing the regulator up out of the way to get it out, and that effectively turns it upside down.Then, any liquid in the low point can flow down the LP hose. The actual lowest low point of the LP system is directly below the LP compartment at the generators solenoid valve. I pulled that hose off and more black liquid came out. I had to remove the solenoid valve to clean all of it out.



So now my questions:

1- When I adjust the LP pressure, should I have any of the other LP appliances on besides the fridge? Should I have them all running?

2- The regulator on the camper now is a Marshall 250 auto-switch. I couldn’t find that exact regulator. Due to the limited amount of space available, the replacement regulator needs to be the same size physically, and it needs to mount the same way. I ordered a Marshall Excelsior MEGR-253H. Is there any reason this one won’t work?

:):)

[BFL13]

Educational thread, thanks! Also admire the DIY expertise. 🙂

[NRALIFR]

The fridge is working GOOD now! It’s on the shaded side of the camper.



The outside temp probe is in the shade but it’s probably still being influenced a few degrees by the hot camper. NWS says it’s 100 here in Phoenix. The AC is blowing directly on the inside thermometer, so it’s not really that cool. It’s about 78-80 inside.



:):)

[NRALIFR]

Got the regulator replaced today. Checked the pressure with the generator, furnace, water heater and fridge all running, and it was still just slightly above 11” h2o.

At 10:00 AM the fridge temps were:



And at 3:00 PM the temps were:



All better!

:):)

[wolfe10]

If this is the OE regulator (i.e. at least 17 years old) replace it-- around $25.

[red31]

I've had a few teaspoons of yellowish oil come tru a Weber Q's regulator, tank pressure propane (100F+) was feed to the Q via a 12' hose.

https://www.propanecouncil.org/uploadedFiles/Council/Research_and_Development/FS_11297%20Propane%20F...

[NRALIFR]

I’m not exactly sure what the liquid is. It’s stinky because it has the smell of the odorant (mercaptan) that is put in LP gas so that we can tell when there’s a leak. The quantity that I cleaned up was too much to be just mercaptan though. Mercaptan is about the stinkiest stuff know to man, and it doesn’t take very much at all to add an odor to a huge quantity of propane.

This is the first time I’ve encountered it in this amount. I’ve had a few drops come out in the past, but this time it was a few tablespoons.

:):)

[72cougarxr7]

Pardon my ignorance, what is the black stinky stuff in your LP gas system?

Been messing with RV's 5 or 6 years now and never run into that one.

[NRALIFR]

Sounds reasonable, having to bottom the adjusting screw seemed like a bad sign to me as well. I should receive the 253H regulator in a few days.

Like I mentioned, the regulator on the camper now is a Marshall 250, but I went searching through all the paperwork I have for this 2001 Lance truck camper, and it looks like the original regulator was a Marshall 254. We’ve owned this camper for over 15 years, and I seem to recall replacing the regulator several years ago while on a trip. Probably just bought what was available at the time, and since we rarely ever use the generator, or multiple LP appliances simultaneously, we never had a problem with lack of LP capacity.

The 254 regulator appears to have a capacity of 210,000 btu/hr, which is very close to the 253H.

Since I now have a manometer, I’ll check the pressure after installing the new regulator, but as was mentioned it should be adjusted correctly already.

Thanks for all the help.

:):)

[dougrainer]

My rule is, IF you have to attempt to adjust a 2 stage LP regulator more than 1 inch W/C, REPLACE it. It has reached the end of its service. Doug

[Old-Biscuit]

1) YES......regulator requires FLOW in order to properly set ....recommended that at least 50% of propane appliances be in service when adjustments are made.

2) That regulator rated at 200,000BTU output-----Marshall 250 auto-switch is rated at 125,000BTU output

A Cavagna 52-A-890 has a 160,000BTU output
https://www.rvupgradestore.com/Two-Stage-Automatic-Changeover-Regulator-p/66-8631.htm


Too high of a flow rating and reg will never be fully in service.

New regulator should already be set for 11" WC

[Bessie-Hunter]

Regulators for house hold use are adjusted with 75% of total load on the system.
I see you have a generator. Start the genny and load it and adjust the regulator to 11" WC.