Accumulator tank/UFH/Solar

[derekh]

I have a 230 sq m bungalow with woodpellet boiler and UFH.  I want to use an accumularor tank so that the boiler does not continually cycle.

1) How do I size the accumulator tank, allowing for the fact that I am thinking of using a DPS unvented tank to also supply DHW through a heat exchanger.  The amount of water in the UHF pipes is 300L  Are these tanks better than the Akvaterm  tanks which have a DHW coil rather than a heat exchanger?

2) I want to add a solar coil to provide DHW in the summer months and aid the UHF during the winter.

3) I also want a connection for a wood burning stove.

Is there a better way of doing this?