Abstract: A method and control system are disclosed for operating an integrated heating system for space heating and tankless domestic hot water heating utilizing an infrared burner module and heat exchanger coil. When the system is below 100% capacity, the burner is pulsed using a constant pulse period and varying the on-pulse width to vary capacity, or where a minimum on-pulse width is maintained the off-pulse width is varied to vary capacity.

Abstract: Domestic tankless water heating is incorporated into a space heating system. The space heating system includes a fluid flow loop with a fluid pump for circulating the fluid in the loop and a remote fan coil for transferring heat to the air in the space to be heated. The heat source is an infrared burner and the heating of the domestic water may be either directly by the burner through radiative and convective heat exchange in an open loop system or by heat exchange in a tube-in-tube heat exchanger which is in series with the fan coil in a closed loop system.