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boiler prob

Wid
Wid Member Posts: 2
in THE MAIN WALL
The max heat limit on the supply manifold is set at 200 and the low temp on the boiler is set at 160. Is this right? The reset button on the max keeps tripping. Can anyone tell me why? 

Comments

  • Brad White
    Brad White Member Posts: 2,399
    Settings not wide enough

    There should be at least a 10F if not a 20F differential between your operating high limit and your safety (reset) high limit. It is best not to "bounce off your safeties" as a control strategy, which you know.



    The safety reset high limit should be on the boiler and the operating high limit could also be on the boiler or in your header.

    Is there a mixing device between the boiler and header?



    What may happen if the differential is too narrow, is the boiler shuts off when it reaches operational high limit setpoint temperature, but can overshoot as it "coasts" over the peak (thermal momentum). Also if you have an interlocked circulator that does not run constantly and shuts off with the burner, the loss of flow can allow the final absorption of heat to raise the temperature above setpoint.



    (In English: If GPM x 500 x Delta-T = BTUH and you drop out the GPM part, the temperature will rise until equilibrium.)



    (In Real English: No Flow, Boiler No Go.)



    As a suggestion, is this 160-200F range an outdoor reset range or normal fixed operational range? Why so high?, I have to ask. Can the operational HWS temperature be 180F and the safety high limit 200?
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
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