Sue asked: > Will 10,000btu boiler heat two double radiators plus a calorifier. How > do I work out what size we need? >
10,000 Btu *per hour*(note the difference) converts to 2.93 kW. On my 59ft nb, spray foam insulated, I had a Mikuni MX40 to operate one large double rad, one medium single rad and a small bathroom towel rail style rad. It could also handle the calorifier coil as well, if required. The MX40 is rated at 4.8 kW max and 2.4 kW at half heat. It took about half an hour to start to get the boat warmer on a chilly day with the Mikuni and longer to really feel a significant benefit (running at 4.8 for the first half hour or so). We also would have had a Morso stove running on cold days. I would think that 2.93 kW would take a while to heat up the boat but, once warm, might just about manage it (depending on external temperatures, boat insulation etc). Having said that though the Mikuni used to kick back into full power on really cold days so I suspect that 2.93 kW might be a little on the light side. You could also try adapting room dimensions and other data in a site such as http://www.radcalcs.com/ to calculate your requirements but it is a bit of a bodge as you are using a house based calculator for boiler sizing. Best I can do I'm afraid. Roger
