I posted awhile back about boilers. I'm still trying to make up my
mind. I am hearing a lot about 3 pass boilers. They are slightly more
efficient and are said to stay that way b/c they are easier to clean.
Are they really a lot better than conventional cast iron boilers? How
long have US manufacturers been making them? Is it really that hard to
keep a conventional boiler clean if you service it regularly or is this
a marketing thing? System 2000 also goes on about how hard
conventional boilers are to keep efficient.

Any thoughts? Thanks.