Forum Discussion

Sauropod's avatar
Sauropod
Explorer
May 29, 2014

LPG Hot Water tank pop-off valve erupted - is this normal?

Hello! I looked through the forums but didn't find exactly my situation. We are first time pop-up owners (2009 Starcraft 2406) and I took it out for an extended adventure the last 5 days. I fired up the hot water heater in order to try out the shower. Though my intent was to use the shower within minutes of firing it up I was delayed by a photo-opp with an elk :-). About 10 minutes after lighting the hot water heater the pop-off valve did its thing and water was pouring out of the external vent. I carefully turned off the hot water heater. The upside was the shower's water was, indeed, hot-hot-hot. I used it again 2 days later but this time I made sure to shut off the flame as soon as I was done with the shower.

Here is my question: On a 2009 Starcraft 2406 (or any other pup w/ LPG water heater) must I light it, use it, then shut it off immediately? I was under the impression it was like the water pump that auto-pressurizes as needed. I presumed once I lit the hot water burner that, if it became too hot, it would back off the heat or shut down completely. However presuming isn't knowing :-) thus my coming here. Before I left I put in a new pop-off valve, new thermocoupler and new element as they were all original and I didn't want any troubles like I had with my initial voyage which saw the factory converter go bad (thanks WFC for the easyish-to-install replacement!).
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10 Replies

  • pojv's avatar
    pojv
    Explorer
    May 30, 2014
    You may find that replacing the whole water heater is not much more than replacing the thermostat unit and is much simpler. I just replaced mine, the heater water 270.00 delivered to my door, it took 2 hours to replace.
    You can PM me and I will provide you a link from an individual that did replace just the thermostat unit.

    Phil
  • Sauropod's avatar
    Sauropod
    Explorer
    May 30, 2014
    Thanks for the link! Pricey little gadget vs the pop-off valve on its own.

    At least I know I wasn't wrong in my initial presumption. Thanks everyone for the help!!!
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    May 29, 2014
    Pressure/Temperature Relief Valves on water heaters are NOT a one time device.
    There is no wax to melt and opening does not make them useless.

    They operate on temperature (210*F) and on pressure (150#....typically close when pressure drops below 125#)

    They have a lever that can be operated to manually open them. Spring loaded snap shut.

    Exercising them via lever once a year is a normal test.


    OP:
    The gas control/thermostat are one complete unit.

    This should work on your 2009 year model....check the gas inlet/outlet size.......LINK
  • ScottG's avatar
    ScottG
    Nomad
    May 29, 2014
    You'll also have to replace the TPO valve (the thing the water came out of) because once they are tripped and the wax inside has melted, they're junk.
  • Sauropod's avatar
    Sauropod
    Explorer
    May 29, 2014
    That is the exact one I have!

    So if I am reading you correctly I'll need to replace the entire gas control unit as the thermostat itself isn't replaceable as a separate item.

    Any recommended places to purchase? I did a check for sit 610 ac3 online and Google didn't do its normal "here are 30 vendors selling it". Does it go by another name?

    I suppose in the interim I can run out and turn it off within 7 minutes or so. Makes for fast showers that way which isn't a bad thing on a 5 gallon tank. :-)
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    May 29, 2014
    Sauropod wrote:
    Thanks everyone for such quick replies!
    It is a Suburban and on the control's top it says "sit 610-AC3". It has a black knob that says "off, Pilot, On" and then in the center it has a selector that lets me pick one of five temperature settings, "High, Medium, Low" with notches to either side of medium. It overflowed whilst on Medium.

    We replaced the thermocoupler originally because it wouldn't light and, once we replaced it, it lit no problem.


    Looks like this? (Sorry pix upside down)



    The 'probe' sticking out the back (with the white cover around it) THAT is the thermostat. Gas control screws on/in tank and the thermostat protrudes into tank into the water.

    Yours is bad...........not controlling.
    Gas control unit has to be replaced.
  • Sauropod's avatar
    Sauropod
    Explorer
    May 29, 2014
    Thanks everyone for such quick replies!
    It is a Suburban and on the control's top it says "sit 610-AC3". It has a black knob that says "off, Pilot, On" and then in the center it has a selector that lets me pick one of five temperature settings, "High, Medium, Low" with notches to either side of medium. It overflowed whilst on Medium.

    We replaced the thermocoupler originally because it wouldn't light and, once we replaced it, it lit no problem.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    May 29, 2014
    Your T-stat has failed.......it should have shut down gas operation when water reached temp setting.

    What Brand/Model of water heater?

    Is it one that has temp setting on gas valve? Pilot light?
    If so........you need a new gas valve as the thermostat is part of gas valve.

    ALL models have t-stats to control temp.
  • bondebond's avatar
    bondebond
    Explorer
    May 29, 2014
    You are correct in assuming that it should shut down the burner when the desired temperature has been achieved.

    My first impression is a faulty TPR valve. If replacing that (one of the cheaper options) doesn't fix it, then I suspect the thermostat control module may be bad.

    Is it an Atwood or Suburban? If it is an Atwood, look at the Atwood Mobile Service Manual for assistance in troubleshooting and replacements.

    I would not think it is the thermocouple as that would prevent gas from ever getting to the main burner if it could not detect heat coming from the pilot.
  • TucsonJim's avatar
    TucsonJim
    Explorer II
    May 29, 2014
    Here are a few things to check. I'm sure others will speak up also:

    1. The pressure relief valve has malfunctioned and is releasing at too low a temperature. I'd change this out because it's cheap, easy and can be found at most hardware stores.
    2. Thermocouple malfunction.
    3. Shut off circuitry malfunction.

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