Alex1

i see. would installing a pump (and perhaps a back-up pump) make the system safer in anyway? regarding the underfloor, our thinking so far was to have a radiator in the bedroom where we don't have sufficient floor area to properly heat the room, however in the main living/kitchen to use underfloor + the stove (its worth mentioning that this is a 12ft widebeam so we have plenty of floor area to hopefully heat the space). it is also worth mentioning that our boat already has 20mm celotex insulating underneath the plywood. i think we still have a bit of thinking to do as to whether we go for that or whether we swap out for rads but i think electric underfloor would be unfeasible for us given our set up.

i see. probably a stupid question, but... when the calorifier reaches the correct temp using the webasto, it will automatically close down? what happens when the correct temp is reached when the heat is coming from the back boiler of the stove?

thanks so much everyone! i think we will go for putting the stove and the webasto in parallel, using the same water circuit (and keeping one coil for the engine). I assume the heat transfer is negligible when one coil heats the domestic hot water to the other coil (say, if the engine heats the calorifier, no heat would be lost to the system attached to the other coil?) If we went for a gravity fed system from the stove back boiler, how would this then combine with a pumped system when the webasto is active? can anyone recommend a flap valve that would be needed to link these up in parallel? is it just the check valves that nicknorman posted? Is there anything else required when putting two different heat sources in parallel on the same circuit, i guess the valves alone will prevent hot water from the stove back boiler from entering the webasto? and in terms of linking things together, is it normal practice to feed the calorifier before or after rads? So the webasto is better used with both rads and the calorifier? rather than just the calorifier?

Hi all I'm looking for some advise on the plumbing and heating system for our new sailaway... We are looking to use both a stove back boiler and a diesel boiler to heat our calorifier/ heating system. Ideally, the diesel boiler will heat our water when there is no fire lit and in the summer and when we have a fire lit in the winter, this can take over heating our domestic hot water. In addition to heating the calorifier, we would also like it install an underfloor heating system and a radiator in the bedroom. My question is: how can these systems be brought together in the easiest way? I have attached three sketches which given that I am very new to this, are probably completely wrong, but I am very happy to be corrected!