Some of you probably read my post about overheat protection. I decided to use copper fin tube above my boiler. I will use a normal open zone valve to protect for power outage. Know I am thinking about using an aquastat to protect against overheating from a bad circulator while Im changing the plumbing around. My EKO is in an outbuilding separate from storage. I would think having it in the water jacket would be best. I noticed a black plastic cap on the top of the boiler and there is a plug under it. Is this wear you would attach an aquastat? I know very little about aquastats. I would need one to open the circuit at 210 and close the circuit at 195 or so to control the zone valve. Could someone point me in the direction of which one would do such a thing?