I am extending our cottage and plan to install a thermal store which I will hook up to our existing combi oil boiler, W23 Esse soild fuel range cooker and for the future it will be ready for solar. I understand that a solid fuel system must be vented for safety reasons and therefore requires a header/expansion tank but if it is feeding into a thermal store (via plate heat ex) which will have an expansion tank is there a requirement for the Esse to also have its own expansion tank or does the thermal store negate the need for this? One other question is regarding the H2 panel which I seen some info on from searching on google. If installing a thermal store as I have described above I assume I would not need something like the H2 panel as the boiler would just cut in when the solid fuel was not supplying the heat input to the store? What are the advantages/disadvantages of the thermal store option over the H2 panel with a vented cylinder option?