I was told by my Mikuni service engineer that it is designed for up to 4 radiators in a 30' pipe run but it is not designed to be the only source of heating as it losses efficiency in this mode without yearly cleans. We have, as well as the Mikuni an 2.5kw gas system which is property vented but takes little space and will warm a 20' cabin space very rapidly with its blowing hot air around. However we understand the best boat warmers for those who spend winter on their boats are proper stove/radiator combos powered by systems like Hurricane sold by Calcutt.
--- On Mon, 12/15/08, Roger Millin <[email protected]> wrote: From: Roger Millin <[email protected]> Subject: [canals-list] Re: boiler size To: [email protected] Date: Monday, December 15, 2008, 10:48 PM 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 [Non-text portions of this message have been removed]
