Failing Aquastat?

T_RO

I have a 20 year old weil-mclean 68V with tankless coil, 4 zones, circulators, Tjernlund PV, Honeywell L8124A,C aquastat.

A couple times this past week my boiler temp was 120 degrees or less before it fired. My settings are 160, 180, 10 diff. Is my lo switch failing? Is there a way to test it? The only thing I've done is run them around a little. This aquastat is ~5 years old.

Edit: add'l info this morning at 400 am house pretty cold when wife got up. no hot water in shower, when I got downstairs boiler was running and at about 130 by then. temps were in low 20's wouldn't have a call for heat started the burner?



Also, I have been thinking about installing an electric hot water heater, if I do so I assume I could go with a different type aquastat that only has a Hi setpoint?



Thanks

billtwocase

power vent

How is it wired? Sounds like they are using B-1, and the fan prover is not always, or delaying the power supply to the primary control.