Going by this figure of 65W per square metre - I would be looking at 13kW per hour though the night on fine days, but if we expect bad weather, we can light the fire in the dinning/lounge kitchen area and drop this to 3-5kW per hour in the bedrooms.
So planning on 16 hours x 13Kw that is 208kw for overnight on fine days, or two winter days with the fire going. We are setting up in-home childcare, so we need to heat most rooms for most of the day. Where do I go from there in terms of Wattage of risers and size of tanks, as there are other factors such as
* how effective the radiators will be as the water cools (what is the minimum temperature you would want your water to drop to?)
* How many days of cold water weather is it worth storing up (that is, how quickly will the tanks lose their heat naturally?)
I'm just a poor boy, I need no sympathy, because I'm easy come, easy go, little high, little low, little ad
Devious Experiments for a Truly Passive Greenhouse!