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Aquastat replacement question please

my Honeywell L4006A1959 aquastat has worked great for 14 years but has now decided to intermittently not turn on when it should.  Tapping or turning the dial ever so slightly will do it’s thing, and you can hear the faint ‘click’ of the micro switch and all is good.  Unless someone has an idea of how to fix/clean this one, I have sourced one and will just replace.

My main question, does my AO Smith TJV120M have a dry well?  I can’t find a reference to it in the manual.  Pic is below, thanks for any advice!



  • pedmec
    pedmec Member Posts: 829
    Yes it does. You can see the screws in the picture. Just loosen the two screws in the rear of control and lift up and forward. The issue will be if the aquastat is installed with the heat transfer compound in the well. Sometimes is in place so long it dries up and the sensing bulb will not come out. You would have to get a new well if that's the case at a supply house or supply.com.

    I would try and find the correct size well and remove the bushing and coupling so the sensing bulb is in the tank reading the correct temperature and getting a faster response. You can get a long shank well that will account for the thick insulation of the tank jacket.

  • capn_mark
    capn_mark Member Posts: 4
    Thanks Pedmec
    HVACNUT Member Posts: 5,490
    Its hard to tell from the pic but those fittings look like black iron, which shouldn't be used on domestic. 
    If that's bushed down from 3/4 to 1/2, then get a longer 3/4 brass well as @pedmec suggested.