On Mon, 10 Jan 2005 00:38:52 -0330, Terry wrote:

So why does the system have to be a closed loop?

For the same reason that domestic systems are closed loops, to keep
oxygen out of the water. Even open vented systems the the water does
not circulate through the header tank (or shouldn't).

Got to admit I don't like the idea of a woodburner with boiler that
doesn't have gravity as the means of circulating the water. If the
pump fails or auxillary battery goes flat the water in the boiler will
boil PDQ and the resultant steam has no where to go...

--
Cheers
Dave. pam is missing e-mail