If this were a continuous commercial operation then heat from one process would definitely be used in another. That does save money. The problem is that resid

If this were a continuous commercial operation then heat from one process would definitely be used in another. That does save money. The problem is that residential use will be variable and intermittent, requiring a host of sensors and valves to turn loops on and off depending on random needs. And when say one process needs to dump heat, but that heat isn't needed elsewhere (ie the hot water tank is already hot) then equivalent backup radiators must on standby to take the load. That is all just too much control circuitry for residential devices normally controlled by just one bang-bang (on/off) control.