Boiler repair. I cleaned the dirty boiler burners. I also found 3 out of 5 thermostats with old batteries, put new batteries in them. Found power head for living room is bad and needs replacement head. A "boiler power head" refers to the actuator mechanism on a zone valve used in a hydronic heating system connected to a boiler; it's essentially the part of the valve that receives the electrical signal and physically operates the valve to control the flow of hot water to different zones in a building, effectively turning the heating on or off in specific areas.