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Dr_Quick's avatar
Dr_Quick
Explorer II
Oct 11, 2016

Propane lesson learned the hard way.

This may be long, but might help someone else.
Woke up to a cold trailer one morning. We use a little electric heater and run it on low for safety reasons, it will generally keep us warm overnight. Then I set the furnace for a few degrees lower as a back up. But furnace failed to work. So I bumped up the T-stat to almost 80 and it came on, but only for a few seconds. We had been running on our first propane tank and I keep checking it as I felt it should be changing over automatically to the other tank soon.
I looked on line for possible causes of the problem and they said low pressure do to faulty regulator. Trailer has a tank on each side. Thinking that regulator had not switched as it was still green, I removed both tanks and weighed them, and Road side was empty, but Curb side was almost full. So I concluded that I had a regulator problem as it had not indicated a switch and maybe a furnace problem too. Switched full tank to the R-tank side as it was working, but it did not make any difference.
I went on line to see how the propane system in our trailer works due to the split system, and I found a person who had exactly the same problem. (Point of information, the R-tank has a pressure reducer on it's side because pressure in tank line can be up to 350#. It reduces pressure to 30#, because line runs through trailer) What problem was, pigtails have a safety valve in them, that if you turn the gas on too quickly the system detects a major leak and a special valve restricts gas flow to a minimal amount. So something like a stove will work, but when furnace tries to come on, because it uses a large amount of gas it detects low gas pressure and will shut down.

To correct problem you have to turn off the gas, and I also lit the stove to relieve pressure in the line. Then wait 15+ seconds, turn gas tank on SLOWLY and that resets the restricter valves. Furnace came on and we were warm. Also the change over pressure valve worked just like it should too.
Apparently originally C-tank valve was turned on TOO fast and had restricted the gas flow so regulator would not switch Then when I moved C-tank to road side I had turned on gas too fast.

There are actually three valves. One in take so if you open valve with out pigtail connected no gas will come out. One that I described in Pig tail. And check valve at each side of regulator, so you can switch tanks and gas will not leak out from full tank.

Forgot about one other item. In the pig tail end there is also a thermal device, that melts and shuts of gas in the event of a fire. it melts at about 250 degrees.

15 Replies

  • Dr Quick, why was the excess flow feature not resetting itself on its own as designed? With all appliances off, if the excess flow feature activates there is enough gas flow to fill the lines and balance the pressure of each side of the little ball and then the excess flow feature resets (spring pushes ball out of the way).

    Yours may have malfunctioned or gunked up. Replace ACME pigtails.

    I can hear the ball when I open a container and then hear it reset.
  • the safety flow valve has caught many many may folks by suprise you aren't the first and won't be the last. many are folks who grew up with the tanks with no safety flow valve and weren't aware that they now are mandated and how they work.

    In fact this summer I came across 3 cases where people were having trouble with propane, and in all three cases they had turned on the tank to quickly set the valve, and didn't know what they had done nore the proper procedure to correct it. You need to releave pressure then very slowly turn on the valve.
  • Sounds like you got tripped up by the afety valve . Good information and thanks for sharing. BTW did I miss why the furnace did not come on in the beginning as there was still LP in the tank? I shall re read
  • 2oldman wrote:
    Dr Quick wrote:
    pigtails have a safety valve in them, that if you turn the gas on too quickly the system detects a major leak and a special valve restricts gas flow to a minimal amount.
    I think that device is in the tank valve, not a pigtail.


    In the Pigtail also. Doug
  • Dr Quick wrote:
    pigtails have a safety valve in them, that if you turn the gas on too quickly the system detects a major leak and a special valve restricts gas flow to a minimal amount.
    I think that device is in the tank valve, not a pigtail.

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