A cool concrete slab is like a black hole for Btus. It gobbles up any heat that dares to get close. The solution is to install a mixing assembly operated by a controller that measures the boiler’s inlet temperature, as well as the water temperature supplied to the distribution system.

In 1905, a boiler in a Boston shoe factory blew up, traveled a great distance through the air, and landed, with delightful justice, in the front yard of the operating engineer’s house. Think it got his attention?

This system is the missing link between one- and two-pipe steam. It was used in tall buildings in the early 1900s because a building this tall wouldn’t work well with one-pipe steam if the supply came up from the basement. 

A tradeoff has always existed between the water temperature at which hydronic heat emitters are sized and their cost. The higher the supply water temperature assumed by the designer, the smaller the required heat emitters and the lower their installed cost. 

High efficiency comes with a price that’s higher than normal efficiency (whatever that is), and because of that higher price, high efficiency is now a subjective term that is open to broad interpretation, and perhaps even reinvention.