Heat service
Expansion tank replacement in NYC
A small tank that protects your water heater, boiler and pipes from pressure. When it fails, other things start to fail. We carry every common size and replace them in Brooklyn, Queens, Staten Island and Manhattan, usually in under an hour.
What an expansion tank does
When water heats up it takes up more space. In an open system that extra volume pushes back into the city water main. Most NYC buildings today are closed systems: a check valve, backflow preventer or pressure-reducing valve stops water flowing back. The extra volume has nowhere to go, and pressure rises every time the water heater or boiler fires.
An expansion tank holds a cushion of air behind a rubber bladder. As water expands, it pushes into the tank and the air compresses, keeping pressure steady. When the bladder fails, the tank fills with water, called waterlogged, and the protection is gone.
Where the supply is closed, the plumbing code requires this kind of thermal expansion control. Hot water heating boilers need a separate, hydronic expansion tank on the heating loop.
Always checked with a new water heater
Installing a new water heater next to a failed expansion tank puts the new tank under the same pressure that damaged the old one. We check it on every water heater replacement and every boiler replacement.
Signs your expansion tank has failed
Water heater relief valve dripping
The most common sign. Without a working expansion tank, the relief valve releases the extra pressure instead.
Boiler pressure climbs when it runs
On hot water heating systems, a waterlogged tank lets pressure spike every heating cycle.
Banging or hammering pipes
Pressure swings can make pipes knock when fixtures shut off.
A new water heater failing early
Repeated pressure stress is a common reason tanks leak years ahead of schedule.
How we replace it
Test the old tank
We check the air valve and pressure. Water from the valve means the bladder has failed.
Match the size
The tank is sized to the water heater or boiler volume and your incoming water pressure.
Set the pre-charge
The air side is set to match your system pressure before it goes in. This step is often skipped, and it matters.
Install and test
We mount and support the tank, then run the heater or boiler and confirm pressure stays steady.
Expansion tank replacement by borough
All sizes in stock, replaced in every neighborhood we serve.
Brooklyn
ZIP codes 11201–11256
- Williamsburg
- Greenpoint
- DUMBO
- Brooklyn Heights
- Cobble Hill
- Carroll Gardens
- Red Hook
- Park Slope
Queens
ZIP codes 11004–11697
- Astoria
- Long Island City
- Sunnyside
- Woodside
- Jackson Heights
- Elmhurst
- Corona
- Flushing
Staten Island
ZIP codes 10301–10314
- St. George
- Tompkinsville
- Stapleton
- New Brighton
- West Brighton
- Port Richmond
- Westerleigh
- Clifton
Manhattan
ZIP codes 10001–10282
- Financial District
- Battery Park City
- Tribeca
- SoHo
- Chinatown
- Lower East Side
- East Village
- Greenwich Village
Expansion tank questions
What does an expansion tank do?
Water expands when it heats. In a closed system there is nowhere for that extra volume to go, so pressure rises. The expansion tank holds an air cushion behind a rubber bladder that absorbs the extra water and keeps pressure steady.
Is an expansion tank required in NYC?
Where the water supply is a closed system, for example because of a check valve, backflow preventer or pressure-reducing valve, the plumbing code requires thermal expansion control, which is normally an expansion tank. Hot water heating boilers also need their own expansion tank.
How do I know my expansion tank has failed?
Common signs are a water heater relief valve that drips, boiler pressure that climbs when the boiler runs, and banging pipes. A plumber can confirm by checking the tank: a failed bladder lets water out of the air valve.
Is the boiler expansion tank the same as the water heater one?
No. The water heater needs a tank rated for drinking water. The boiler uses a hydronic tank on the heating loop. They are not interchangeable.
How long does replacement take?
Usually under an hour, including setting the air pre-charge to match your water pressure.
Relief valve dripping?
It is usually the expansion tank. Call and we will check it the same day.
646-980-2411