Replacing a honeywell aquastat relay


Old 01-22-12, 08:03 PM
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Replacing a honeywell aquastat relay

Is this very hard to replace?
My heat wasn't working and I narrowed the problems down to the circ pump. It wasn't getting voltage, so I bypassed the Aquatsat and hooked the pump up to a cord. I have heat again. Is there some way to further test the Aquastat. It is a Honeywell aquastat relay type L8148A. thanks
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Old 01-23-12, 03:24 PM
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No, not terribly difficult if you have reasonable electrical and mechanical skills.

With that aquastat, if there is a heat call and the burners fire, and the pump don't run, and you have no voltage at C1 and C2, there's really only one thing it can be...
Old 01-23-12, 07:35 PM
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If you are doing it when it is cold outside, I would recommend having a spare well on hand or at least know where you can get one immediately if you need one. Mine was so corroded that I had to drain the boiler and replace the well. In case you don't know it, the well screws into the boiler and the relay probe fits in that well.
Old 01-23-12, 08:57 PM
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Looking at the schem of my L8148A, it appears that the B (blue) terminal on the high limit is the same as the C1 (but on the other side of the relay ). Could be useful in a pinch, but I wonder if the extra current (burner plus circulator(s) now) would end up killing the relay entirely.

One could set up an outboard relay using B (on the high limit) and C2 feeding it, then the circ(s) on a separate 110v feed from that.

(Note: I havent tried this, this is only an assumption from the given schematic , so only test this if you know what you're doing, pre/post test connections and observations etc.)

At least it would save ripping the aquastat/well out during the heat season ??
Old 11-25-12, 01:40 PM
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circulator pump not working all the time when called for

I have been having a problem with the boiler not coming on when the thermostats call for heat. When It first happened I turned the power switch to the boiler off and back on and the circulator pump came on and then the boiler fired up. This just started doing this, and at different times I will have to do the same thing to get the boiler to kick back on. When it does come on, the house heats up fine.

Is it most likely the aquastat relay or could it be something else?


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