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Proper Aquistat settings??

I have a 4 section Weilmclain 68 series boiler. I have always kept my setings at 160- 180. I am doing my best to conserve energy this year and make my boiler as efficient as possible. I recently purchased a new digital aquistat (71224U) and a new intelledyne HW+. I have an older 41 gallon Amtrol. I wanted to put this out there and see if any one had any suggestions on further trying to economize such as maybe lowering the stat to 130-160 or any other suggestions??


  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    lowering the stat to 130-160

    I had an old GE boiler and my main heat load was radiant in slab. I had the house thoroughly insulated, and later put in Marvin windows. I lowered the aquastat so it ran between 130F and 140F. This may have lowered the oil bill somewhat. The former owner had the limits as tight as the aquastat would go, so it cycled every 15 seconds or so. That is why I raised it to 10F, and it cycled on for on about 30 seconds and off for about 45 seconds. I tried to widen the range, but the expansion tank was not big enough, and the relief valve on the water feeder would weep all the time, so I set it to 10F. I always got enough heat, since the boiler was about twice the size my house needed.

    That boiler was not a condensing boiler, and I assume it condensed a lot. I had it 32 years and the former owner had it 25 years. When I had it replaced, it showed no evidence of rust to speak of and it was not leaking. But that was dumb luck. While I am not a professional, let me suggest you never let it go below 140F. The professionals here may have even stricter recommendations.

    The way I got greater economy was to replace that 55 year old oil burner with a gas fired mod-con with outdoor reset. I also got greater comfort as the outdoor reset allowed the water temperature going into the slab to be closer to what the house needed, preventing wild temperature swings.
  • icesailor
    icesailor Member Posts: 7,265
    Aquastat settings:

    If your Amtrol is a "Boiler Mate" indirect with a circulator tied into the heat system and you don't have a tankless heater, and you have your aquastat set to act as a triple acting control with a high limit and operating control side, set the operating/low side to 140 and the high side to 160 degrees. You could try setting the "low" side to 130 degrees but you may get some condensating. But, you will really only be using the Amtrol "Indirect" where, when it runs, the coil will be pulling hot water into the boiler when it starts and you won't get the cold water shock you will on the heat side where the heat system is cold. 

    Because you are in "The Shoulder Season" where you don't need design day temperature, your house will be very warm. Chances are that your house is over radiated and you don't need higher temperature water. If the house gets cold, turn up the high limit 10 degrees.

    It's worth a try. 
  • billtwocase
    billtwocase Member Posts: 2,385
    do you have

    a zone valve or circ for you Boilermate? If circ, is it wired into ZR on the old aquastat?  Reason I ask is that if the temp falls low, and the switching relay for the Amtrol only controls the circulator, you will not over ride the low limit setting, and make hot water.
  • billtwocase
    billtwocase Member Posts: 2,385
    cold start

    The temp may never fall too low, but I like to see a temp of about 110 degrees maintained. Cold start boilers, if they are not 3 pass, are no fun to clean, and they tend to live a shorter life
  • Ron Jr._3
    Ron Jr._3 Member Posts: 603
    edited April 2011
    I have an old pin style boiler too

    Connected to an indirect and wired to cold start . Peeked in on it for a few days when I woke up ( with the boiler temp at it's lowest ) and never saw it go below 115 degrees . I might connect a boiler water post purge control this summer and see how it affects the fire side .

    That old 68 though ............... I'd keep the temp fairly high ( no cold starting that baby ) . I've seen too many 68s go cold for some reason or other and watched the coil gasket or section O rings leak .
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