Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

How to minimize Indirect Cycling

I've got an indirect tank hooked to my boiler. I find that it is cycling way more often than I would like. Additionally In summer I don't want the boiler if possible.

I don't know if they exist, but I'd like to replace the aquastat with on that will heat the up to the boiler temp of 170 then let the tank cool all the way down to 130+/- in theory that would solve my cycling problem and during the summer the boiler might only kick on twice a day max.

I have a Weil Mclain Aqua Plus 45. On the DHW I have a mixing valve to protect from scalding.

Any other work arounds to do this?


  • Robert O'Brien
    Robert O'Brien Member Posts: 3,541
    W-R makes a temp control with a 45* differential if your indirect has a standard well. You can also use a timer to turn off DHW calls.

    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • Gordy
    Gordy Member Posts: 9,546
    you don't want to take the tank temp to 170. Decreases tank life, and creates more loss at higher storage temps. If I'm understanding your goal correctly.
  • Brewbeer
    Brewbeer Member Posts: 616
    edited February 2016
    How often does it cycles when you aren't using hot water?
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread: http://forum.heatinghelp.com/discussion/154385
    System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    I would make sure it's piped properly with heat traps, and insulate the pipes. Also double check for any leaky faucets.
    It's also possible contacts in the control/aquastat could be bad, causing this short cycling.

    There was an error rendering this rich post.

  • SWEI
    SWEI Member Posts: 7,356
    What kind of boiler is heating the indirect?
  • Zman
    Zman Member Posts: 7,572
    I think you need to narrow down the cause of the cycles.
    Sometimes it is a result of the on/off differential on the tank being set to narrow.
    It could also be caused by an undersized or fouled heat exchanger. In this case the boiler is cycling because the indirect cannot transfer the heat as quickly as the boiler produces it. This is common in the amtrol tanks.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein