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BaileyJ · 04-24-2009, 06:18 AM

I'm having problems with my motorhome mounted LP tank. I have an Extend-a-stay T fitting and the external tank works fine but the coach tank does not. The tank was just filled and the vapor vent indicates pressure is present when opened. I tried opening the main shutoff valve with the system open but nothing flows. Do these valves go bad. Sad thing is we are/were getting ready to take a trip.
It's a 2006 Southwind 37C. Thanks in advance for any advice

Joe-K · 04-24-2009, 06:50 AM

The only thing that I can think of is that the overflow prevention valve inside the tank is preventing flow. Propane tanks are built with an internal safety device which prevents the excess flow of gas in the event of a pipe or hose rupture. Typically this overflow prevention device would only activate if a line was broken, but can also activate if it senses a quick flow for other reasons.

The most typical cause of this is opening the onboard tank valve quickly when there is no pressure in the RV lines. This cause the gas to quickly fill the lines and trips the safety valve. Opening the valve with the system open will actually trip the valve and shut off the propane as well.

As a test, try shutting off the onboard tank valve for a while, then turning on a stove burner to relieve any pressure in the lines. Finally shut off the stove and very slowly open the onboard tank valve. You should hear a slight hiss through the regulator as the piping inside the coach is pressurized. Once that his is over (maybe 2-3 seconds) you can fully open the tank valve. If that works, the cause would be the internal valve and was caused by the quick reopening of the valve after the tank was freshly filled.

BaileyJ · 04-24-2009, 10:09 AM

Thanks Joe,

Your procedure worked! This started when I removed the external tank for travel. I guess I opened the onboard tank valve too quickly afterwards.
Lesson learned.