I have just joined,but I think I have read most of the boiler room prior.We are pouring the floor on the garn building this mourning. The forum is full of great info a lot of it is over my head eg, delta t , head pressure, heat load etc.I'll tell you what I have any tips on design would be greatly appreciated. Garn 1500, old house 650 sqft not that well insulated addition 3000 sqft new construction,1800 sqft shop.The house has a wood electric forced air furnace and in floor heat in the basement slab which is pressurized and heated with an electric hot water heater and a coil on the wood furnace. The new addition stays fairly warm with this but the old house needs help from space heaters even though the forced air has been piped into it.I think the wood furnace its undersized at 80,000 btu.The shop is electric baseboard .Our electric bills are huge upto $900mon in mid winter. So I decided to invest in the garn mostly from what I have read on these forums.We live on 30 acres with hunderds of standing dead soft woods fir and pine due to the bug kill here in B.C.My plan so far, water to air exc. in the forced air, water to water ex. attached to the infloor, water to water for dhw, cast iron space heater in the old house and water to air blower in the shop.The shop and house have separate underground lines 60' shop 100' house.Thanks