rescue37-
Can you say why you are recommending pressurized hot water system over steam?
My perspective is that steam is
1) safer- the heat rises naturally, and not by means of a pump. Returns to the boiler naturally as well (gravity). The pump is an added component and a potentially volatile one at that.
2) easier to maintain- no need to bleed the system and each radiator
3) uses less water- a couple of gallons total
4) at least as efficient (cost wise)
Now if you were talking about a water system without radiators, i.e. radiant floor heating then I’d agree that a water system has advantages. Specifically, that since the water in the pipes is heated to a lower temperature (100-105 degrees instead of 160-180 for water radiator), it can be modified to use geothermals. But the cost of laying radiant floor tubing is enormous.