We have a three-year-old, Superstor-45 indirect hot water system connected to our natural gas boiler. The problem is that the hot water tank must have priority over the remaining four heating zones. During times of heavy hot water use such as when we have overnight guests, the circulator to the hot water tank is often running, therefore, we can't heat our home for several hours at a time as no zone may run until the hot water system shuts off.. This is a problem in winter and we sometimes lose several degrees of house temperature.
I'm thinking of adding a tankless hot water system to use as a pre-heater, feeding hot water into the indirect tank. This should greatly shorten the running time of the indirect hot water tank, allowing our heating zones to function more efficiently and to better respond to their respective thermostats.
I would appreciate any thoughts or suggestions on how I can overcome the problem I describe.