Hi, can anyone help a 57yr old builder with a 55yr old eco friendly wife? I’m looking at the heatrae Sadia heater. I can plumb it and get my sparky to live it up so installation costs will be very low. We live in an old(small) house with poor insulation (plenty in loft but 9inch brick walls). heating is an oil fired Rayburn, something I converted years ago, just a plain wick burner but it heats the water for us two to shower daily. Other heating is two oil filled rads and a log burner. So,, as we get older we need more/some comfort. Given that we only need 5 rads totalling around 30’000 btu’s, will a 9 or 11kw HS do the job? and at what cost? My Mrs is against using too much oil and nearest gas is 4miles away.