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Honeywell L4006A-2023

gibson Member Posts: 15
I have a tankless water heater in my oil-fired steam boiler. The hot water temperature is controlled by a Honeywell aquastat #L4006A-2023, which is ten years old. When the weather is 50 degrees outside I get little hot water. The aquastat is set for 150 degrees, which should be plenty hot enough. The boiler will turn on if I manually turn up the aquastat to 160 degrees. Do I need a new aquastat? If so, which one replaces the L4006A-2023? Thanks.


  • tommyoil
    tommyoil Member Posts: 613
    Be sure

    that the water level in the boiler is sufficient to fully submerge the coil. A half submerged coil may be to blame.
  • Big Ed_4
    Big Ed_4 Member Posts: 2,696

    150-160 could be a little light for a coil. But you don't want to raise it too high to break steam either.

    Coil hot water heaters are not my choice. Then put them in a steam boiler it drops a notch futher down on my list. To adjust temp you need to set it for the shower but then sink temperture is too hot. You have a lot of system loss mataining a hi temperture boiler all year round. Steam boiler , during the summer raise water level all the way up and drop it to 1/3 durning the heating season. If water below coil then either you are using the wrong boiler or coil.
    I have enough experience to know , that I dont know it all
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