Get ready for winter: the heating maintenance checklist for NYC homes and buildings

By GW Mechanical Corp. Published October 9, 2026. About a 12 minute read.

The first hard freeze in New York is not the time to find out the boiler will not fire. Every October our dispatch board fills with the same calls: no heat, a dead thermostat, a water heater that chose a cold week to leak. Most of them were avoidable with an hour of checks and a proper service visit in the fall. This is the checklist we use ourselves, written for homeowners, landlords and building managers in Brooklyn, Queens, Staten Island and Manhattan.

Why the work has to happen before the cold, not after

A heating system that sat idle from May to October has had five months for small problems to develop quietly. Pilot assemblies collect dust. A circulator pump that ran fine in April seizes after a summer of sitting still. A low-water cutoff on a steam boiler gets a crust of sediment that keeps it from tripping when it should. None of these announce themselves. They show up on the first night the thermostat calls for heat and nothing happens.

There is also a practical reason to move early. In the first cold week of the season, every plumber in the city is on no-heat calls, and the supply houses run through common parts such as ignition modules, gas valves and circulators. A problem found in October is a scheduled repair. The same problem found in the second week of December can mean a wait for parts while the building sits cold, and for a landlord that is a Class C violation with penalties accruing every day.

Work through the sections below in order. The first two take fifteen minutes and cost a few dollars in batteries. The boiler service is a job for a licensed plumber. The rest you can do yourself with a flashlight and a little patience.

1. Replace the thermostat batteries first

This is the single most common no-heat call we take that does not involve a broken part. A large share of thermostats in NYC homes, including many programmable and smart models, run on AA or AAA batteries, or use them as a backup when the wiring does not supply constant power. When the batteries fade, the thermostat may show a dim or blank display, lose its schedule, or simply stop sending the signal that tells the boiler to run. The boiler is fine. The house is cold anyway.

• Replace the batteries every fall, whether or not the thermostat is complaining. Use fresh alkaline batteries, not rechargeables, which run at a lower voltage and can trigger low-battery behavior early.
• Check every thermostat in the building. Multi-zone homes often have three or four. A dead thermostat on one zone leaves one floor cold while the rest of the house is fine, which is confusing to diagnose at midnight.
• Confirm it actually calls for heat. Raise the setpoint five degrees above the room temperature and listen. Within a minute or two you should hear the boiler fire or the circulator start. If nothing happens, note it for the service visit.
• Reset the schedule if the batteries went flat over the summer. Many thermostats drop their program when power is lost and revert to a default that may not match how you live.
• Smart thermostats that lost Wi-Fi over the summer should be reconnected now, not when you are trying to turn the heat up from work in January.

2. Replace the batteries that protect your family: smoke and carbon monoxide alarms

Heating season is carbon monoxide season. Every fuel-burning boiler, furnace and water heater produces it, and a cracked heat exchanger, a blocked flue or a backdrafting chimney can push it into living space without any smell or visible sign. New York City requires both smoke alarms and carbon monoxide alarms in every apartment and house. Fall is when they need attention.

• Change the batteries in every alarm that takes replaceable batteries. Do it twice a year; the fall thermostat change is a good reminder for one of them.
• Press the test button on each unit, including hardwired alarms, which still rely on a backup battery when power fails.
• Check the manufacture date printed on the back. Carbon monoxide sensors wear out. Most CO alarms are rated for five to ten years of service and chirp or display an end-of-life warning when they are done. Smoke alarms are generally replaced at ten years. An alarm past its date should be replaced, not just given new batteries.
• Consider sealed ten-year alarms for rental units. They cannot have their batteries removed, which solves the tenant-pulled-the-battery problem that makes landlords liable.
• Location matters. A carbon monoxide alarm belongs within about fifteen feet of every sleeping area and on each level of the home. One more near the boiler room door is cheap insurance.

If a carbon monoxide alarm goes off, get everyone outside, call 911, and do not go back in to investigate. If you smell gas, leave the building and call 911 or Con Edison at 1-800-752-6633 from outside. Then call us.

3. Have the boiler serviced by a licensed plumber

A real annual service is more than a technician looking at the flame and leaving a sticker. This is what we do on a pre-season boiler visit, and what you should expect from anyone who services yours.

Gas boilers, steam and hot water

• Clean the burners and the heat exchanger surfaces. Dust, rust flakes and spider webs in the burner tubes cause delayed ignition, yellow flame and soot.
• Check the ignition system. Pilot assembly and thermocouple on older boilers; igniter and flame sensor on newer ones. A dirty flame sensor is the most common cause of a boiler that lights for a few seconds and shuts down.
• Run a combustion test. A combustion analyzer reads oxygen, carbon monoxide and flue temperature at the vent. This confirms the boiler is burning cleanly and venting safely, and it catches a cracked heat exchanger before it becomes a CO problem.
• Inspect the flue and chimney connection. Rust holes in a flue pipe, a loose connector, a chimney liner that has collapsed, or a bird nest at the top all push exhaust back into the basement.
• Test every safety control. The high-limit, the rollout switch, the pressure relief valve and, on steam, the low-water cutoff. These are what stand between a malfunction and a dangerous one.
• Check gas pressure and the gas valve, and look for leaks at every joint with a detector, not just soap.

Hot water (hydronic) boilers specifically

• System pressure. A residential hot water boiler typically sits around 12 to 15 psi cold. Pressure that keeps climbing, or a relief valve that drips, almost always means a failed expansion tank.
• Expansion tank precharge. The air side of the tank is checked with a tire gauge with the system pressure removed. A waterlogged tank is replaced; they are inexpensive and cause an outsized number of winter calls.
• Circulator pumps and zone valves. Each zone is run and the pump listened to. A circulator that hums but does not move water, or a zone valve that does not open fully, will show up as one cold zone on the first cold night.
• Air in the system. The loop is bled at the radiators and the air separator checked. Air pockets cause gurgling, cold spots and, in bad cases, a circulator that cavitates and fails.

Steam boilers specifically

• Water level and sight glass. The glass is cleaned so the level can actually be read, and the automatic feeder checked.
• Low-water cutoff. Float-type cutoffs are flushed to clear sludge; probe types are cleaned. This device shuts the burner off if the boiler runs dry, and a stuck one is how boilers crack.
• Pressuretrol and pigtail. The small looped pipe under the pressure control clogs with sediment and leaves the control blind. It is cleaned or replaced every season.
• Main vents and radiator vents. Failed vents are the reason steam systems bang and heat unevenly. Main vents at the ends of the basement mains do most of the work and are often decades old.
• Skim and flush if needed. Oily, surging water in the sight glass means the boiler needs skimming. Dirty water is blown down.

Oil boilers

Oil systems need a new nozzle, a new oil filter, a cleaned strainer and a combustion adjustment every year without exception. Check the tank level and the fill and vent pipes outside, and order fuel before the first cold snap when delivery schedules stretch out.

If the service turns up a cracked heat exchanger, a boiler past twenty-five years, or a repair bill approaching half the cost of a new unit, it is worth reading our guide on repair versus replacement before winter forces the decision for you. Our annual maintenance plan schedules this visit automatically each fall and gives plan members priority dispatch when the cold hits.

4. Give the water heater the same attention

A tank water heater works harder in winter because the incoming city water is colder, and a heater on its last legs usually fails between December and February. A half hour of maintenance now tells you where it stands.

• Flush the tank. Connect a hose to the drain valve and run a few gallons out until the water runs clear. Sediment on the bottom of a gas tank insulates the burner from the water, wastes fuel and causes the rumbling sound many people mistake for a bigger problem.
• Test the temperature and pressure relief valve. Lift the lever briefly with a bucket under the discharge pipe. It should release water and then reseat without dripping. A valve that keeps dripping afterward needs replacement.
• Check the anode rod if the heater is more than three to five years old. The sacrificial rod is what keeps the tank from rusting through; once it is consumed, the tank itself starts corroding.
• Confirm the setpoint. 120°F at the tap meets the NYC minimum and limits scalding. Buildings with long pipe runs or recirculation may need a higher tank setting to deliver 120°F at the far fixtures.
• Look for the warning signs. Rust streaks on the tank jacket, moisture at the base, a corroded drain valve or rust-colored hot water mean the tank is near the end. A heater past ten to twelve years is a candidate for planned replacement on your schedule rather than emergency replacement on the tank's.
• Tankless units need an annual descaling flush with a pump and vinegar or a descaling solution, plus a clean inlet filter. NYC water is relatively soft, so scale builds slowly, but a yearly flush is still what keeps a tankless heater free of error codes and at full output.

Not sure what size you would want if the tank does fail? Our water heater size guide walks through 40, 50 and 75 gallon choices.

5. Walk the radiators and baseboards

The boiler can be perfect and the house still cold if heat is not getting out at the other end.

• Hot water radiators and baseboards: bleed each radiator from the top floor down until water, not air, comes out of the bleed valve. Vacuum dust out of baseboard fins and make sure the dampers are open.
• Steam radiators: check that each radiator pitches slightly back toward the supply valve so condensate drains. A radiator that is level or pitched the wrong way will bang. Confirm the supply valve is fully open; steam valves are on or off, not throttling valves. Replace any air vent that hisses constantly, spits water or never opens.
• Clear the space. Furniture, curtains and radiator covers that block airflow can cut output by a third. Pull sofas a few inches off the baseboard.
• Convectors and unit heaters in commercial spaces and lobbies need their fins vacuumed and fans checked. Dust buildup over a summer is substantial.

6. Protect the pipes from freezing

Frozen pipes are a cold-snap emergency we see every January, and they are almost always in the same places: an unheated garage, a crawlspace, an exterior wall, a vacant unit, or a basement where someone shut the heat off to save money.

• Insulate exposed water pipes in unheated areas with foam pipe sleeves. It is inexpensive and takes an afternoon.
• Shut off and drain outdoor hose bibs. Close the interior shutoff, open the outside spigot to drain it, and leave it open. Disconnect hoses. A frost-free sillcock still freezes if a hose is left attached.
• Keep heat on in vacant units and empty buildings at no less than 55°F. The cost of heating an empty apartment is a fraction of the cost of a burst riser.
• Seal drafts near pipes: gaps around dryer vents, cable penetrations and old window frames let cold air blow directly onto plumbing.
• Know where the main shutoff is and make sure it actually turns. Every adult in the house, and the super in every building, should be able to find it in the dark. A burst pipe that runs for an hour while someone searches does far more damage than the freeze itself.
• During a deep freeze, let a faucet on an exterior wall drip and open the cabinet doors under sinks so warm air reaches the supply lines.

7. Check the venting and the condensate line outside

High-efficiency boilers and water heaters vent through plastic pipe out a side wall rather than up a chimney, and that termination is at the mercy of the weather.

• Find the intake and exhaust terminations and make sure nothing has grown over them, no one has stacked anything in front of them, and the screens are clear.
• After snow, check them again. Drifted snow against a low sidewall vent shuts the boiler down on a pressure switch fault, and in the worst case causes it to recirculate its own exhaust. Keep a path cleared.
• Condensate drain. Condensing equipment produces acidic water that drains through a small line to a floor drain or condensate pump. Make sure the line is clear, the pump runs, and the neutralizer cartridge, if there is one, has media left in it. A frozen or blocked condensate line will shut the boiler down.
• Chimney-vented equipment should have the chimney cap and the top of the flue checked for nests and debris, and the cleanout at the base emptied.

8. Do not forget the drains and the sewer

Winter storms bring sewer backups, and a basement full of sewage during a cold snap is the worst kind of emergency. Before the season, run water in every floor drain to fill the trap, confirm the sump pump runs and its discharge line is not frozen or blocked, and if the building has a history of backups, have the main line camera-inspected or hydro-jetted while the weather still allows it. If you have a backwater valve, check that the flapper moves freely. Restaurants should have grease interceptors pumped on schedule going into the busiest months; our restaurant maintenance service covers that.

For landlords and building managers: the extra items

• Keep a written log of the fall service, every repair call, and the time heat was restored. If a tenant files a complaint, this record is what shows you acted promptly.
• Larger residential buildings must have their boilers inspected annually and filed with the Department of Buildings; small private homes are generally exempt. Confirm your building's status and filing deadline so an inspection lapse does not become a separate violation.
• Post the super's and the plumber's number where tenants can see it, and tell tenants how to report no heat to you before they call 311.
• Lock up the boiler room and make sure the emergency shutoff switch at the door is labeled and working.
• Fuel oil buildings should have a delivery contract in place and the tank filled before November.
• Vacant apartments are your responsibility to keep above freezing, and the risers running through them serve the occupied ones.

Your emergency plan, written down now

Even a well-maintained system can fail. The difference between a bad night and a disaster is knowing what to do in the first ten minutes. Keep this somewhere visible:

1. The number of a licensed plumber who answers at night. Ours is 646-980-2411, 24 hours, in all four boroughs.
2. Where the main water shutoff is and how to close it.
3. Where the boiler emergency switch and the gas shutoff are.
4. The rule for gas: smell it, leave, call from outside.
5. The rule for a locked-out boiler: one reset, maybe two, then stop. Repeated resets can flood the combustion chamber with fuel.

Before a storm or a forecast deep freeze, you can also schedule a visit in advance so we are already on the calendar.

The checklist in one place

Most of this list is yours to do in an afternoon. The boiler and water heater service is ours. Call 646-980-2411 to book a pre-season service in Brooklyn, Queens, Staten Island or Manhattan, or ask about the annual maintenance plan so it happens every fall without you having to remember.

Questions