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Aquastat Setting... sorry for beating a dead horse

ChasMan
ChasMan Member Posts: 462
in THE MAIN WALL
Your coil won;t put out 190 mdegree water. It probably will put out 160 though which is crazee hot. Nice for shaving. Personaly, Id dump that coil and replace it with an indirect. Or, a cheap electric water heater if you are pinching pennies. If you can make good hot water with your coil at 160 then no need to go to 190 on the high limit. I used 140 / 160 last winter with mine and it was ok till it got seriously cold out then I had to bump it to 160 / 180 to keep the house warm.

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  • Jake_7
    Jake_7 Member Posts: 2
    Aquastat Setting... sorry for beating a dead horse

    I have been looking around for a while and finally found this forum. I think I found the answers to some of my questions, but I want to summarize and get some verification.

    I have a tankles coil boiler for heat and DHW. It has an aquabooster and is controlled by a Honeywell Triple Aquastat. I have been looking for answers about the most efficient way to set the aquastat... These are my conclusions:



    How it works:

    1.When a call for heat comes from my thermostat in my living area, the circulator pump will come on, sending hot water through my radiator.

    2.If the Aquastat is set at 200*F and the diff to 10*F, when the water temp drops below 190*F the boiler will fire until the water temp reaches 200*F -- then it will shut off.

    3.As long as there is a call for heat, the circulator pump will remain on... unless...

    4.The DHW is in use (say I am in the shower)... If the LO is set to 160*F (with the DIF at 10*F as was mentioned before), when the water temp fell to 155*F the circulator would shut off until the water temp rose to 165*F, at which point it the circulator would turn on again.

    5.If when the water temp reaches 165*F, and there is still a call for heat, the boiler and circulator would continue to run until the temp reached 200*F (the HI setting), repeat conclusion 1 through 3.

    6.If when the water temp reaches 165*F, there is no call for heat, both the boiler and the circulator would shut off.

    7.With the LO set to 160*F and the DIF at 10*F, with no call for heat or DHW, the boiler will turn on when the temp drops below 155*F and will shut off when it reaches 165*F to maintain the water temp in the coil.

    8.To avoid scalding a mix valve should be installed in the DHW line to bring the water temp down to a reasonable level.

    9.During heating season, the LO setting is almost useless because the water temp will likely be high due to calls for heat from the thermostat in the living area.

    10.When not in heating season, the HI setting is useless.



    How to be efficient:

    This I'm not really that sure about... but as far as I can tell...

    1.The HI should be set between 200*F and 180*F because the hotter the water in the radiator, the more efficiently and quickly it will heat the house.

    2.The LO temp should be at least 20*F below the HI to avoid lock up.

    3.The DIF should be set to at least 10*F -- better if higher (20-25*F) because the boiler will be less likely to short cycle.



    Ok... so really, I'm more educated, but still confused. This would be easier if I wasn't married. I don't mind taking short lukewarm showers and living in a cold house. My wife however...



    So this is what I am going to do. Please let me know if you think this will be reasonably fuel efficient:


    Set the Aquastat as follows:

    HI 190*F

    LO 160*F

    DIF 15*F


    Check for a mix valve somewhere, so we don't get scalded by 190*F water...


    Thanks!


    Jake

    Somersworth, NH

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