Steam balancing

scott22nyc

I manage a 1960’s building with half the apts facing the front and half facing the back. The 2 sides are fed from separate pipe runs from the boiler.

We have the back apts consistently 3-4 degrees colder than the front. We are already master vented with a candelabra of barnes and jones big mouth vents at the end of each run.

Would you recommend to throttle the warmer side down by removing a few vents and slowing the steam arrival there? Or install a motorized valve to close off the warmer side so the back/colder apts can get more time with steam before the warmer/front opens up?

Or maybe a 3rd option?

Thank you in advance.

Jamie Hall

Well… let's start off by asking is this one pipe or two pipe?

If it's one pipe, start off by slowing the vents in the apartments which are getting too warm. You may be able to control the problem entirely that way. If it's two pipe, a somewhat similar ploy — only this time partly close the inlet valves to the radiators in the apartments which are getting too warm.

A motorized valve is a possibility. It would probably be better to reverse the logic you mention, and have it close if the warm side got too warm near the end of a run rather than open at some arbitrary time from the beginning, but that's a control detail. What is NOT a control detail is that both sides of that valve would need to be dripped to a wet return and the valve absolutely must be a full port design, preferably a ball valve. There are also pressure considerations, as with the valve closed the steam main beyond will be at atmospheric pressure and you would need at least 28 inches of height from the water line to the bottom of the main for each pound of pressure that your pressure control will allow to avoid flooding the main. I would regard that as a last resort.