into the furnace when the pump is turned off by the automatic controller. Install on existing outside wood furnace Decrease wood consumption in the winter Heat domestic hot water... Purchase Online Purchase Online Solar Kit For Domestic Hot Water without existing outside wood furnace How an indirect drain back solar water heating system works: Water is heated... in a water tank, similar to the tank in any regular water heater. The water is then transferred to your hot water heater. Install without existing outside wood furnace Reduce hot water...