Mysterious Propane "Leak"

JimK-NY wrote:


Thanks for the reply. Sorry for the delay but I just got out of the hospital. The camper is a Northstar Igloo. I think it was sold as a 2005 model but actually built in 2004. I am positive the HW heater is Atwood. I believe the furnace is also Atwood but cannot check on that or the stove top until I am able to climb stairs in a couple of days. The is no connection for a BBQ grill and the refrigerator is compressor.

I used it a couple of years as a fulltimer but since then it has been stored in the winter outdoors in Long Island, NY. Repairs have been minimal. I replaced the ignitor on the HW heater. I have replaced the pigtails every 2-3 years due to hardening. In addition to replacing the pigtails last month, I also decided to replace the switch over regulator due to age.

Hi Jim,

Hope you are doing well now, no worries on a later reply.

On the older campers, (20 year range +/-) there was a trend at the time by the RV manufacturer's to stick with certain brands for both quality and pricing on what that appliance manufacture offered.

It appears in your case, Atwood Mobile was the choice for the water heater, odds are high the furnace and the range. The fridge and AC unit could be Dometic as they offered both, or they split up in Norcold fridge and Coleman Mach AC.

I do total camper restorations & localized water damage repair as a somewhat extreme retirement hobby. Water damage is the main issue requiring restoration, but I go through every appliance and mechanical running gear etc. in this restore process. Most all these campers are in the 15 to 20 year old range which is about where yours is at. I do not do this for a living, so my sample set is close to 20 campers so far for this information. We have a few RV tech's on the forum who may have lots of years on this to confirm what I have been seeing.

In this restoration process, I normally end up pulling all appliances out of the camper that are mounted in the siding to do a bench test, clean up and repair on all of them. I have to fix the rot, so out comes the siding mounted appliances. When it comes to the LP system, I test each appliance separate and then as a complete system. There are 3 tests to make this complete and I use either a manometer or a precision LP gas gauge. The gauge is quicker, but if a question comes up, I verify it with the manometer.

You could very well have small LP leak or leaks on the appliances. In fact, I have yet to restore a 20 year old vintage camper without some LP gas leak somewhere.

Lets start with the furnace. The gas valve leaking is about a 50/50 issue with a fine leak. This may be aggravated by the camper not being used in a long time. When the outside of the valve has corrosion fuzz on it, odds are not good for it. While the valve tests great for no leaks at the start, once the valve is cycled, tests there after show it does not always seal up tight. See the pics from the bench test.

The fuzz on the outside of the valve.


The bench test setup using the gas gauge.


Confirming the leak at the valve


I even test the new valve before installing. They do work from the start thankfully.


These RV LP gas valves are not rebuildable, all you can do is replace them. I suspect what happens is, being stored outside in an unheated space, spring time condensation sweat when the metal was cold, then started to warm up, starts the bare aluminum into a corrosion cycle. You being in NY and I am in OH, that cold/frozen and warm thaw cycle happens. The valve internally gets a small level of corrosion on the valve seat and it will allow a fine leak. All I can do is replace the valve and move on.

The Atwood water heater has the issue worse I think as the valve is closer to outside for corrosion. See here,

The gas valve out on the bench test. When they look like this, odds are high they will fail the LP leak test.


After cleaning up the heater and the outside of the gas valve, I do the LP test.


Yes, it leaks, the bubble test shows the location after the gage test fails.


New valve next to old, replace, retest, and all works well and passes.


New valve installed and under use testing




The Atwood stove, since it is inside the camper, the burner knobs I have not had much issue with. But the stove regulator, I can have a diaphragm leak. This leak was on a newer camper, only about 2 - 3 years old at the time. I'll leave the new Dometic non working stove regulator issue for another time.




The Domectic fridge, it uses a different type of gas valve. So far I have not had the fridge gas valves fail the leak test, even when 20 years old. I'm sure they can, but they do not seem to be as pronounced as the water heater being the worst, then the furnace.

Cleaned up mounting bracket on the old gas valve.


Leak check


Live test


When the camper is all back together, I do a total system LP test. This checks for anything in the system for leaks and tests the main tank regulator.

I do these 3 tests.

1. System pressure drop test. I hook up the gauge at a stove burner as it is easier to get into the system. You charge the system, shut off both LP tanks, bleed the pressure down to 8" WC to open the main tank regulator and then wait and look for a pressure drop. The time length may change by state etc. For sure nothing less then 3 minutes and no drop at all. I test longer into the 15 minute time period. After doing the bench tests, I normally have no issue passing 15 minutes. But, the main tank regulator and the hoses are always suspect. If the hoses are hard as a rock, I change them before I start. I have had many main tank regulators be bad, for regulation more then diaphragm Leaks.

2. Main regulator pressure set point test. Next if I have no leaks, I do the main system pressure setpoint. Here I need to get upstream of the stove regulator. Since I was on the gas burner control I have the down stream stove regulator pressure already, but I do not totally know the main system pressure. If I can get my 11" WC on the main pressure, I'm good to the next test. This can be where I start finding main tank regulators be bad. I adjust the main tank regulator as needed to get up to or down to 11" WC.

3. Main regulator lock up or max pressure test. This test point is still at the stove upstream of the stove regulator, but it tests the max pressure when the furnace and water heater are in operation. You do not want above 14" WC or a lot below 11"WC. This is where an old or sometimes new, tank regulators fails the test. A 20 year old RV style tank regulator is often a problem. Not always, but often. The system will not maintain stable enough not not go above or below the limits. Trying to adjust the setpoint is all you can do. So you replace the main tank regulator and start over on the leak checks and go again through the test.

The tanks hose fittings, either on the high side or the low pressure side have been a leaks source at the fittings. The main LP gas line sch 40 black iron pipe joints normally come out OK. The 3/8" copper hook up tubes to the appliance, if they are loose, they can leak. Leak bubble solution finds them.

The end results of my learnings are, RV grade LP gas components are not high quality like in a home or industry. Everything is throw away and not the greatest quality even when new. It's sad. I also see new campers being built now with flex rubber lines in place of older hard lines. I'm not sure I really like that idea. They are faster to install, but longevity the jury is out, along with the oil in the hose issues that can come from rubber lines.

Hope this helps

John