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marbil_146's avatar
marbil_146
Explorer
Dec 30, 2015

Problems with 6 year old Atwood hot water heater

This water heater (pilot only model) G 6A7 has had a problematic Robert Shaw Unitrol thermostat (91602) for several years and kept getting worse over time,as it seems to cut out on a high limit,even with the water in the tank still cold......some days it works fine other days I have to relight it over and over...........The pilot is fine,it will stay on pilot forever.
There is a definite "thunk" sound when it cuts out,unlike the normal "off cycle"click.
NOW!.....A month ago I had a new (same type)control put in and it has worked perfectly until 2 days ago and the exact same symptoms have come back to haunt me.
It can't be anything other then another bad control......anyone else had this experience?
.The burn is good,nice and clean and quiet.....the tube and vent ok......a real head scratcher......maybe it's time to replace it with a relight model.

9 Replies

  • 72cougarxr7's avatar
    72cougarxr7
    Explorer
    Jan 01, 2016
    Glad you got it working! I also have a pilot only Atwood in my TT. I used the trailer quite a bit this summer and was happy with its performance. Sometimes simplicity is best!
  • marbil_146's avatar
    marbil_146
    Explorer
    Dec 31, 2015
    RJsfishin wrote:
    Good point.
    You said "they".....does that mean a commercial did it, and there is a warranty ??


    I purchased the control in one RV supply place in Phoenix and took it to another RV dealer for installation ......But RJ. You have solved my problem...when you pointed me to the fact that if the TC is slightly misaligned, it could keep the pilot on but not create enough milliamperes to keep the main gas valve open,and that seems the case as two test runs have worked just fine.......and it was out of alignment....I'm the cause of my own problem as a few days before it all started I was in there cleaning out desert dust and must of moved the TC adjustment......It moves very easily and I don't know if something is missing in the mount,as the old one was fixed solid,but I don't care as long as I can monitor it.
    So thank you all,for your input.....this site has always had some real knowledgeable people who are quick to respond.
  • RJsfishin's avatar
    RJsfishin
    Explorer
    Dec 31, 2015
    Good point.
    You said "they".....does that mean a commercial did it, and there is a warranty ??
  • marbil_146's avatar
    marbil_146
    Explorer
    Dec 30, 2015
    Chris Bryant wrote:
    RJsfishin wrote:
    It seems you would have replaced the TC along w/ the gas valve.
    I have seen where the TC was good enuff to keep the pilot on, but not good enuff to hold the gas valve open.


    There's really only a single safety valve in there, but the point is good- I've seen thermocouples which opened up when too hot.
    .

    They changed the thermocouple at the same time....my point is why would it work fine for a month after being installed,then just a start acting up like the old one. You'd think if there was a fault,it would show up right away.
    With both the control and Tc replaced.......what else is there?
  • Chris_Bryant's avatar
    Chris_Bryant
    Explorer II
    Dec 30, 2015
    RJsfishin wrote:
    It seems you would have replaced the TC along w/ the gas valve.
    I have seen where the TC was good enuff to keep the pilot on, but not good enuff to hold the gas valve open.


    There's really only a single safety valve in there, but the point is good- I've seen thermocouples which opened up when too hot.
  • RJsfishin's avatar
    RJsfishin
    Explorer
    Dec 30, 2015
    It seems you would have replaced the TC along w/ the gas valve.
    I have seen where the TC was good enuff to keep the pilot on, but not good enuff to hold the gas valve open.
  • Chris_Bryant's avatar
    Chris_Bryant
    Explorer II
    Dec 30, 2015
    If the pilot flame is too large, it will overheat even on pilot only and blow the eco it should just barely envelop the tip of the thermocouple.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Dec 30, 2015
    When you replace the gas control did you replace pilot assembly OR are you still using the old Robertshaw Pilot Assembly?



    Replace with the current Jade pilot assembly
  • enblethen's avatar
    enblethen
    Nomad
    Dec 30, 2015
    Have you cleaned the thermal couple? Clean with steel wool and make sure it is directly in the pilot flame.
    Take it loose from the thermostat and make sure the connections are clean and have some de-oxidation grease on it before re-attaching.

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