This is an interesting set up!! The apartment heater is fed from the water heater with recirculating domestic hot water. Basically a heating coil you would see on any hot water heating system. I'm having issues getting hot water through the coil. It's coming in hot and cools off about 20 degrees on the leaving side of the coil with the fan off. I have bled the system a bit and seem to have good pressure on the leaving side but I know it could be pressurized from return side. Ofcourse the valves are frozen and unable to shut off. Any ideas on how to make my customer happy?!?!