Erratic Steam Heat

Are your steam mains properly vented?

temperature variance if that extent is not so unexpected. so what you are saying is

are there radiators in the hall where the thermostat is or is the hall heated by the apartments because it is internal and has common walls with apartments.

while you have remote temps are you able to set your thermostat to respond to those.

besides @Steamhead main venting, is it two pipe or one pipe system. air valves or steam traps require balance and maintenance you have to go unit to unit and see if each radiator is heating during a heating cycle.

is there an outdoor temp sensor so you get a sense of whether the difference increases or decreases as outdoor temperatures are warmer or colder? you could probably graph utdoor temp from some weather source although you probably could place a remote sensor outdoors and add its input to graphs as future data.

by quick look at your graph you get a significantly different result later in the season vs. shoulder season (presumably longer vs. shorter run times to satisfy the hall temp). but that is a guess by dates and doesn't actually tell outdoor temps. and it seems like the apartments that are slower to heat actually deliver more btus in longer runs as they overtake the other units in the later season, or did you do some maintenance that might explain the threshold approx between nov. and dec. 2R (orange trace) seems especially erratic compared to others.

of course the perrenial question here of how low can you go with pressure to help radiators fill evenly and not carry water up. you don't mention any clanking or other problems so maybe this is well attended to. do you have a quality steam pressure gauge that can actually read in useful low range, e.g. 1 psi or less?

Hay, @archibald tuttle

I looked up the degree day data for Brooklyn and pasted it over the temperature  chart and tried to line up the days and dates as close as I could.   there does not seem to be a correlation to the weather at one end of the graph to the other end of the graph compared to the center where the boiler performed at its best in keeping the temperatures at a relatively consistent temperature between 71° and 77° on December 5, 6, 7, 8, and 9.  The high and lows that go way past the 75° target seems to have no rhyme or reason when matched to the weather data

Of course some of the very low temperatures could be a result of leaving a window open to counteract the overheating.  Tenants seem to do that from time to time.  Open a window and forget to close it before they leave for the day, only to come home to a cold living room.  Then the window gets closed and the temperature spikes again.  So without real time surveillance of the building, those temperature readings may not be so helpful.  I have heard the procedure is called using your “Double Hung Thermostat”

or someone cooking in the apartment with the thermostat or tenants opening and closing radiator valves.

Are you referring to the 4F temperature spikes ? Have the spiked temperatures actually been verified ? Many seem during the daytime. They look too high and narrow to be real.

I'd swap sensors around. before I did anything else. See if the spikes follow the location or the sensor device.

The mains in the basement.

For better balancing you want fast main venting in the basement and then tend toward slowing down the hot rooms at the radiator rather than speeding up the cool rooms within reason. Not sure what you have at this point for venting on the mains or the radiators.

@dmoder , go here:

https://heatinghelp.com/find-a-contractor/state/NY/

Let us know how it goes.