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Hydrolevel aquastat

bob eck
bob eck Member Posts: 930
When you have an older oil boiler with traditional Honeywell triple aquastat and you then replace it with this hydrolevel aquastat what type of energy savings can the home owner expect?
If you add the outdoor reset sensor to this control will the home owner expect an higher energy savings?



  • Jamie Hall
    Jamie Hall Member Posts: 22,972
    None, if the old one was working right.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    Almost none. Don't add outdoor reset on an old oil boiler if you don't have protection for low temperature return water into the boiler. It does have circulator hold off, but it may not be enough.
    The second is with ODR, the boiler will short cycle most of the winter (doubled with the fact that it's probably way oversized), and will in fact be less efficient.
    If you want to do ODR, you'll need a properly piped/sized/controlled buffer tank & mechanical boiler protection (mixing valve).
    Changing the aquastat's main benefit is Circulator Hold Off, more accurate temperature reading, and low water cut-off (when you use their HydroWell).
    The Economy Features, may modestly help with the short cycling.
  • leonz
    leonz Member Posts: 1,055
    edited June 2022
    Based only from personal experience with 2 bad hydrolevel 3250 plus units on a keystoker kaa-4-1 boiler I would never replace a mechanical aquastat with a digital one.

    I had the first one fail and nearly boil out the boiler and the second one failed when I was running it on oil to test it and the computer in it turned the LWCO function off; there was a lot of filling of the swear jar and cursing the coal stoke manufacturer due to their lack of interest and concern for my installation even after
    I offered to put them up in a local motel at my expense to solve this issue.

    I should have sued them for selling a defective product.

    I replaced the defective computer controlled aquastat with a Honeywell L8124L and a McDonnel & Miller RB-122-E low water cut off and I have slept well ever since.