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How to use an aquastat

Brad White
Brad White Member Posts: 2,398
There may not be a thermostat per se but may be an outdoor sensor coupled to a water supply sensor ("aquastat" is a possible term for this, to us) to perform what is known as outdoor reset.

Is your system water or steam? Either use the same principle but steam relies on a certain number of cycles per hour, more per hour the colder it is outside. That system too may have an "aquastat" (strap-on sensor) on the return to the boiler.

Are there any indicators of brand? Any photos you can post?

Are the numbers you see on a valve on radiators? You may be in luck.

The need for a specific water temperature at a given outdoor temperature varies with every building and if no individual unit control, you really cannot guarantee a specific temperature in any one unit.
"If you do not know the answer, say, "I do not know the answer", and you will be correct!"

-Ernie White, my Dad


  • Jason Quinn_2
    Jason Quinn_2 Member Posts: 6

    Hi all and thanks in advance for your help. My husband and I purchased a 3 flat bldg. which has no thermostates. Our only way to control the boiler is with an aquastat. We want to keep the temperature at about 70 degrees for our tenants. However, we don't know how to convert the numbers on the aquastat to give us an appropriate temperature. Can someone please help us. I don't want to turn the aquastate up too high and end up getting an outrageous heating bill.
  • Jason Quinn_2
    Jason Quinn_2 Member Posts: 6
    Can someone PLEASE help me with this aquastat dilema

    My husband and I just purchased a 3 flat bldg. which has absolutely no thermostat. We want to keep the temperatures in the apartments around 70 degress. What temperature should I set the aquastat on to maintain 70 degrees in the units? I have no clue what these numbers on the aquastat mean.
  • Weezbo
    Weezbo Member Posts: 6,232
    Glenda, while we know what the #'s mean,

    there are some variations as to what is what.

    there are aqua stats that bolt to pipes, are in the boiler,. in the pipe, stuck to the skins of appliances... it would help define what might be happening with either a post of a J Peg as an attachment of your next reply (lower left hand corner of orange screen) or some info as to what type boiler or heating fuel source and emitters you might have, the near boiler piping may even reveal that the boiler isn't even the heat source and that it is connected to district heating...off an injection system with outdoor reset and variable speed injection with the boiler valved off from that system...

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