Any reason not to use the supply valve to fine-tune temperature in 2 pipe system?

That appears to be what is called either a "SWRF-B" or a "SWRF-A" valve, currently made by MEPCO, the successor company to Dunham. Not sure if you have a 3/4" or the 1/2" version.

It is indeed for a two pipe system and is indeed adjustable.

The kicker is, that it is essentially two valves in one. The plastic handle part is for on-off control, and there is another part which is only supposed to be accessible for metering adjustment via a special pin-type spanner wrench available from MEPCO at an exorbitant cost.

Oh lord where do building management get their ideas? 

I love my super. He's a great guy and a good friend. But sometimes he perplexes me.

Among several reasons, he's said that the inlet valves on the radiators in our building (they're labeled Dunham) shouldn't be open partway, because (variously) they aren't designed to hold back pressure and that closing them part way could result in more banging.

Of course, they only change steam traps on cold radiators, so the system is wildly out of balance, with most never changed in people's entire lifetimes. Since some people are so overheated, people then shut the valves all the way off. Which, when a significant portion of the building shuts their steam inlet valves, probably worsens pressure problems.

Now that the building is replacing the 1960s boiler with a fancy new one, we're on a mobile boiler in the mean time. People are really friggin warm. One of my radiators got up to 235°F and started leaking steam. I think that means they're up to at least 5psi steam, if I understand the charts correctly.
Apparently other people are having problems with leaks. The faster firing boiler *probably* is amplifying all the problems if not entirely responsible.


I told them all of this could happen if we simply went to replace the "bad" old boiler without even considering addressing the steam traps, but nope, nobody listened, and I'm a bit embarrassed to say I find this affair kinda funny. But I'm too polite and like them too much to point and laugh and say "I told ya so!"

My mother lives in a mid/late 20's building and their fancy mechanical consulting, well, consultant, company (they may have done the boiler replacement design) told the board to tell Shareholders that they should only use the valves on their two pipe system (strangely, a lot of people had 'upgraded' their radiators to convectors, probably in the 50's and 60's to make their units more modern looking) for on and off rather than modulation. I rolled my eyes at that - the perfect example would be a brutally cold sunny day with a north wind - the south half of some units would be boiling, the north half of those units would be chilly w/o heat and the north wing cold - the whole point of two-pipe is adjustability. Their excuse, I mean reasoning, was balance or pressure....

My mother being elderly likes it warmer as did my father - they replaced most of their convectors with CI radiation and always keep the living room radiator off and don't have a bedroom radiator and she's never been cold in those rooms.