New York City writes indoor temperature into law. From October 1 through May 31, residential buildings with tenants are required to maintain specific minimum temperatures, and the requirements are precise enough to be checked with a thermometer. This article explains what the rules say, what changed in recent years, and what a building’s heating system has to be able to do to meet them.
The daytime rule
Between 6 AM and 10 PM, the rule has two parts. When the outdoor temperature falls below 55 degrees, the indoor temperature in every apartment must be at least 68 degrees. The outdoor reading is the trigger: on a mild November afternoon above 55 degrees, a building is not required to heat, and on a raw morning below it, the building must reach 68 inside regardless of how the system feels about it.
The overnight rule
Between 10 PM and 6 AM, the indoor minimum is 62 degrees, and there is no outdoor trigger at all. Whatever the weather is doing outside, apartments must hold 62 degrees through the night, every night of heat season. This is the part of the law that changed in 2017 — the overnight rule previously had its own outdoor threshold, and the amendment removed it. Buildings that still run their boilers on the old logic fall short on cold nights without realizing the rule beneath them moved.
Hot water is part of the same law
Year-round, not only during heat season, residential buildings must supply hot water at a minimum of 120 degrees at the tap. Boiler work scheduled for the fall usually addresses both obligations at once, because in many buildings the same plant handles space heating and domestic hot water.
What a building has to do to be ready
Meeting the numbers is a mechanical question long before it is a legal one. A building that passes heat season without complaints has usually done specific things before October 1:
- The boiler has been serviced, with combustion checked and controls verified, before the first cold morning rather than after it.
- On one-pipe steam systems, the air vents on radiators and steam mains have been inspected, because a clogged vent keeps steam from reaching the apartments furthest from the boiler.
- The controls that decide when the boiler fires — timers, outdoor sensors, indoor sensors — have been set for the current rules, including the fixed overnight minimum.
- The apartments that historically run coldest, usually top floors and units at the end of long steam mains, have been checked directly instead of assumed.
What tenants see when it fails
The pattern of a heat season failure is consistent. The apartments closest to the boiler are comfortable, the furthest are cold, and the complaints arrive from the same lines every winter. That geography is diagnostic: it points to venting and balancing on steam systems, or circulation on hot-water systems, rather than to the boiler itself. A building that responds by simply running the boiler longer overheats the near apartments to warm the far ones, which is the oldest and least effective correction in the city.
The calendar, in short
October 1 is not the date to begin thinking about heating. It is the date the requirements take effect. The preparation belongs to September, and in buildings with a history of cold-apartment complaints, to August.
Pacific Air HVAC is an HVAC contractor based in Clifton, New Jersey, fifteen miles from Manhattan, and works in buildings across the five boroughs. The office can be reached at (973) 210-7060, Monday through Saturday, 8AM to 5PM.