How to connect a central heating system with multiple heat sources

[Adam]

On 14/02/2021 at 15:19, john6767 said:

The have an Alde boiler that heats radiators, and hot water with a coil in the calorifier.  In addition there is a second coil in the calorifier connected to the engine cooling.  To get free heat in the boat whilst cruising we simply turn on the Alde circulation pump and it basically uses the calorifier as a heat exchanger to transfer heat from the engine cooling to the radiators.
 

Works quite well for a no cost option, but don’t forget to turn the circulation pump off when you stop or you will have no hot water in 30 mins!.

 

Has anybody successfully got there pump to run independently from firing the eberspacher up? There must be a lot of boats out there (including mine) with a twin coil calorifier that is one switch away from free engine heat!?