Cast iron boilers with the "pins" on them are a pain to clean. The 'steady
state efficiency' of any vertical pass boiler is about the same as a
horizontal pass boiler, but the 'seasonal efficiency' is not.

wrote in message
oups.com...
When I say conventional, I mean a pin type boiler. Maybe this is the
wrong term. Better refers to 3 pass boilers. the only advantages I
see is that they are slightly more efficient and easier to clean. I
assume they are fairly new for residential use. I am just trying to
determine if they are significantly better than the pin type and why.
Thanks.