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I'm not understanding the aquastat set points.
I just installed a switching relay for an additional zone on a boiler. I fire the boiler and set the hi for 190* and the lo for 170* and set a 20* diff. The boiler is cold. So...it fires but it goes past the hi limit and continues to fire as the call for heat kicks in. I panicked at 210* and shot the hi limit down to 160* and it turned off. In trying to understand this, I'm guessing the boiler has to reach idle lo temp first and turn off at 180* but not go past 190*. If there's a call for heat I understand the burner kicks on BUT ONLY IF THE HI LIMIT IS NOT REACHED AT WHICH POINT IT RUNS UNTIL 190*. Am I wrong with this? WHAT DON'T I GET WITH THIS? 210* is 20* above the hi limit. The 20* diff setting is the operating limit for the lo limit control and has nothing to do with the hi limit. Sooo....this should play out as an operating range of 160*-180* (including factory fixed limits) and fail open at 190* due to the hi limit setting which is supposed to be a safety. Do you get this?
I'm heading towards steam with this. I left it set for 180* HI, 160* LO and a 20* DIF.
At what temperature does 12 PSI water flash to steam? Is there a typical lead time for the aquastat bulb to heat up before registering the correct temperatures to the aquastat? Is the bulb liquid filled?
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