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Boiler Not Turning On At Low Set

I have a Peerless tankless hot water system. Used for heat and hot water. The aquastat went the other day. I replaced the aquastat and also the mixing valve while I was at it. I have the aquastat set to 160 low / 180 high / 15 Diff. The boiler temp drops to 125 - 130 before it fires again. I checked the thermo capillary bottoms out into the well. The tube is brand new. I didn’t kink or damage it. Was very careful. Shower starts hot. Then gets warm to barely warm. Am I missing something obvious? Thanks for any insights.


  • nunesman
    nunesman Member Posts: 5
    edited December 2019
    After reading the thread on aquastat function, I put the high limit at 200. The low is at 170 with a 20 diff. Boiler seems to be kicking on around 160 as expected and shuts off at 180.

    In the thread Ron said to set the low temp to the point where you lose hot water and add 10 degrees. Not exactly sure how you do this, ie set low temp to point where lose hot water?
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,386
    edited December 2019
    If you need the hi on 200, and the low on 170, something else is wrong.