Honeywell aquastat burner / pump problem

roperman

Hi there - I have Honeywell triple aquastat relay that runs a forced hot water system with 2 zones, and an indirect fired water heater. It's an oil burner that I converted to gas about 10 years ago and it's been stable since 1999 when I bought the house. I turned up the heat today and noticed the boiler was cycling on and off every 5 minutes or so. After standing and observing for about 10 minutes I determined that when the thermostat calls for heat, the burner goes on until the high setpoint is reached. When the burner stops, the circulator pump for the zone starts pumping. They both aren't on at the same time. After the pump has pumped cold water into the boiler, the lowpoint is tripped, the burner goes on, and the circulator pump stops. It just cycles back and forth, they can't run at the same time. Not the most efficient way to heat the house!

My aquastat model is L8124C - do you think it's time for a new aquastat? Honeywell has a replacement part "L7224U Oil Electronic Aquastat® Controller" for about $129.

Thanks for any advice in advance.