So for those of you who haven't followed my previous threads ( http://forum.heatinghelp.com/discussion/comment/1362385#Comment_1362385
) about the system I, more or less, as board president, supervise, it's a two-pipe system with Trane concealed convectors, a lot of them supplemented or replaced with additional convectors or radiators and some mangling, original Heggie-Simplex boiler, 10-12 year old powerflame burner and new R&D controls. The building is 8-floors. Also of note is that none of the original convectors had valves, control was purely with the damper.
My immediate problem is two-fold: steam through the returns, which I've traced back to a specific return and am dealing with getting a trap replaced to deal with that - the suspect trap isn't readily accessible and requires removing a convector to get at it. The pressure has been at 1-1/2 pounds and I talked the janitor into 1 pound. No improvement, but also no worsening.
The other problem is a bit bigger. There are two steam mains which snake their way west from the boiler room, one on the north side of the building, about 65' long and one at the south, about 97' long. The rooms serviced by the north main have been cooler this year, partially, I think by the sensor locations of the new R&D system - the system is satisfied even if the rooms are too cold or the main rooms cool down too quickly. That's easily fixable by moving them, which is in the works. That said, however, this side of the building has always been a problem - it's cooler, not just because of the north exposure and despite replacement windows in most of those units. The temperature difference can be nearly 10-12 degrees! Almost all the traps, including the F&T traps were replaced two years ago. The longer main has a Hoffman FT015H4 and the shorter an FT015H3, both are located after a cooling leg at the end of the runs with a drip down into the returns.
There are 5 returns, each with an F&T trap and a pump back into the boiler. One interesting feature of the north main and north return are that they supply the lobby convector - which then ties into a return from the south main and has an air vent at the convector itself.
I've attached plans of the first floor and basement showing the layout of the mains and returns. Still working on the upper plans. I have the feeling that the heating wasn't entirely satisfactory even at day one, either through insufficient radiation or poor system management, since there are lots of replacements with larger radiators or convectors and the rear bathrooms have had one-pipe radiators tapped onto the hybrid convective/radiator originally provided (essentially a six-floor pipe radiator with each floor having the pipes enclosed in a convector flue with registers near the floor and ceiling). A building built by the same architect-developer two years later had conventional cast iron radiators....
Any suggestions as to where I should start directing my attention beyond sensor location and making sure everything within units is in good working order (i.e. traps, dampers, valves, etc).