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Honeywell L8148E Low Voltage Problem
I have a boiler with 3 zones and a Honeywell L8148E 1216 aquastat. I've recently started having a problem with my heat, and I think I've traved the problem to this aquastat.
The system works fine most of the time.
Thermostat calls for heat, aquastat gets 24V between B1 and B2, damper opens, and the burner fires up. But a few times each day, the burner doesn't fire despite a continuous call for heat, sometimes for hours. When this happens, the aquastat has only 12V between B1 and B2, so the damper never opens and the burner never fires. If I close the relay in the aquastat manually, the cycle finishes and everything keeps working for many hours.
I have seen other posts about no voltage on those terminals, but I can't find anything about this half-voltage issue I seem to have. I'm wondering if anyone knows what might cause that to happen randomly, and/or whether or jot replacing a part in the aquastat could fix it. Or, should I just replace the aquastat itself?