Aquastat or what??? Boiler Runs constantly.

PoorerRichard

Our small home has a 25 year old Kenmore gas boiler with induced draft and intermittent pilot ignition. It's worked fairly well over its lifetime and we want to get a few more years out of it. Suddenly, last night, it ran constantly and no thermostat adjustment or even switching it off stopped the boiler. I had to go downstairs to the basement to shut off the emergency switch. I figured the thermostat was shot and disconnected the wiring from the back of the thermostat. The furnace ran anyway, so thinking there was a wire short, I disconnected the thermostat wiring inside the aquastat/control housing. The furnace ran. I found even with the thermostat disconnected above, I still had 26 volts across the T1-T2 terminals. Does this point to a failed aquastat? Sears Parts has replaced the original control with the Honeywell L8148E HI limit/Control. It's a burden this time of year, can these things be repaired? I'm good with a soldering gun, etc.

PoorerRichard

Beckett makes a replacement control the Aquasmart 7600B (low voltage model) that I am agreeable as a replacement, too. Does any one have any specific tips? I'd like to be able to use the existing immersion well so I don;t have to drain the boiler and baseboards.

STEVEusaPA

This is part of your failing aquastat from the other post. I already gave my recommendations. You don't have to change the well if you don't want to use the low water cut-off (Hydrolevel), but I think you should. It's not that big of a deal to drain a system and refill/purge to a professional.
If you were really smart, you would put in some valves to isolate the boiler, and isolate the circulator. I would add some air elimination. Then you won't have to completely drain the system to change a circulator, well or relief valve.

PoorerRichard

Thanks, Steve. I'm not sure, but I could always replace the immersion well and drain/refill/purge during the warmer months. Right now, I just want to get through the winter without having to get up all night long serving as a human thermostat! I purchased the Beckett 7600B aquastat and will install it today. I really appreciate your helpful advice.