repair of boilers, the hand of the master throws and twists the nuts, close-up

and appliance boiler boilers buildingservices calorificvalue closeup construction craftsman domestic energy fix gas gasboilder gasfiredboiler guy hand handyman heater heating heatingengineering heatingplant heatingsystem heatingvalue home hot house install installation installing insulation job maintenance male man manual master newbuilding nuts occupation pipe pipeline plumber plumbing repair repairing repairman service skill system throws tool twists utility warmwater water worker wrench