Plumbing / Heating

[Alastair]

On 28/08/2020 at 14:45, Tony Brooks said:

I am not sure that I follow those diagrams. The stove and radiators need piping so the hot stove water will circulate by gravity for safely reasons and one calorifier coil can be put in series with that circuit or in parallel with the rads, depending upon where the calorifier and stove is situated.

 

I very much doubt you an run under floor heating on an un-pumped system but pumped circuits on stoves are best avoided. You could pipe the under-floor system as if it were one more radiator. That is in parallel with the other radiator and the calorifier but I  doubt it would work when running on gravity.

 

The Webasto can use the same water as the stove so it could be in parallel with the stove but in summer it may lose heat via the stove. This very much depends upon where you fit the valve that you use to isolate the radiators and stove from the calorifier and that depends upon where         everything is located in the boat.

 

That leaves the calorifier engaging coil on its own and no heat exchanger is required. Heat exchangers are sally required when you want to use waste engine heat to heat the rads because most engine runs their coolant at b6 to 16 psi and boat central heating systems are not normally pressurised.

how about a gravity system for the stove, and a motorised valve to shut this off from the webasto? The Webasto being on a parallel circuit to the stove, with the 'out' pipe from the webasto having a valve. Open valve when webasto is called for heat.

[TheBiscuits]

19 hours ago, Alastair said:

how about a gravity system for the stove, and a motorised valve to shut this off from the webasto?

 

I've seen this done with two flap valves, one either side of the Webasto, rather than a motorised valve.  The water pressure opens the flaps when the Webasto pump is running, so no extra wiring needed and less to potentially go wrong.  It's very important to fit the flap valves the correct way round though!