I have a large convetional dhw copper cylinder. It has 3 seperate coils. At present they are all connected together in series and are heated by the gas boiler. When it was installed the idea of having 3 coils was: one for the gas boiler and one each for solar panel and a domestic waste hot water heat recovery system. Neither of the last two are implemented yet.
I now find myself with a plentifull supply of firewood. I would like to install a woodburning stove with boiler. 2kW output to the room and 3kW to the boiler would be ideal. My problem is that the fireplace is remote from the cylinder and the route between the two does not lend itself to constantly rising 22mm pipes required for a gravity system. I am aware of the need for an open vent and a header tank. My question is: Can I use 15 or even 10mm plastic (threadable) pipe to carry primary hot water to the cylinder if it is pumped? At what rate would I need to pump the water around and would a central heating pump be suitable. I know that the open vent must be at least 22 mm. I can contrive to put the header tank and the vent on the floor above (higher than the cylinder). Any suggestions about a suitable woodburner also welcome.