I help manage a small pre-war coop in NYC with one-pipe steam heat. Having just started up our boiler for the season, and having done a lot of reading on here, it seems that our system maybe poorly designed. At start-up, it took about 20-30 minutes for the pressure to start climbing. I could only see two small main vents.
One of the main vents hissed the entire time. The pressure appears to be set to 5psi. During this time, the automatic water-fill valve activated.
Last heating season, I've been around the boiler and it seems to fire about 3 minutes at a time before cutting off at 5 psi. When I've been in other people's units, I heard hissing from radiator valves for several minutes at a time.
Assuming no one in the building is experiencing comfort issues, is this operation particularly fuel inefficient? For the three coldest months, we consume 1,400 therms a month to heat about 12,000 square feet.