Combined Boilers

For houses where the main heating equipment also provides the hot water, the DOE-2 simulation engine calculates the hot water energy consumption. There are two different types of combined boiler, direct and indirect. Direct combined boilers heat the water upon demand. Indirect combined boilers have a storage tank, similar to a stand-alone hot water heater, which provides hot water upon demand. The boiler maintains a steady temperature within the hot water storage tank.