No Hot Water From Your Boiler or Water Heater
Last updated Reviewed by Waseem Shahzad, Lead Technician
No hot water usually comes from one of three setups: a gas or electric tank water heater, a tankless unit, or a boiler that makes your hot water through an internal coil or an indirect tank. Knowing which one you have narrows the cause fast. If you smell gas, leave first and call from outside.
Call 24/7: (631) 414-7141Smell gas or hear a carbon monoxide alarm? Leave the house first, then call 911 or the gas utility from outside.
Which kind of water heater do you have?
A tall tank with its own burner or electric elements is a standalone water heater. A small wall-mounted box with a vent is a tankless unit. If there is no separate heater and your hot water comes from the boiler, either through a coil inside it or an insulated indirect tank piped to it, the boiler makes your hot water.
If the boiler makes your hot water, no hot water and no heat together point to the boiler. Hot water gone but heat working points to the coil, the indirect tank, a mixing valve or the zone that feeds the tank.
What can you safely check yourself?
For a gas tank, check that the pilot or burner is lit and the gas control is on. For an electric tank, check the breaker. For a tankless unit, note any error code and make sure gas and power are on. For a boiler-fed system, check that the boiler is running and its pressure is normal.
Do not relight a pilot if you smell gas. If a tank is leaking from its body, shut off the cold water inlet and the gas or power. See water heater repair and tankless water heaters.
When should you stop and call right away?
Call right away if the tank is leaking, the relief valve is discharging, you see scorching or smell exhaust at the vent, a pilot will not stay lit, the boiler has no heat as well as no hot water, or a tankless unit keeps showing the same error after one reset.
- Gas smell or CO alarm: see what to do first.
- Boiler down too: see no heat.
What does K2 fix on a no-hot-water call?
We find which part failed and quote it before any work. On tank heaters that is often a thermocouple, gas valve, element or vent. On tankless units, an ignition part, board or scaled heat exchanger. On boiler-fed systems, the coil, the indirect tank, a valve or the boiler itself.
Recent jobs include a failed gas water heater replaced in East Meadow, a blocked water heater vent cleared in Huntington Station, a boiler leak and hot water coil repair in Huntington, and a tankless heat exchanger, board and valve replacement in Lindenhurst.
Recent no-heat calls we fixed
No hot water: gas water heater replaced, plus a new AC capacitor
East Meadow · Water Heater Replacement · July 2026
A no-hot-water call. The gas water heater had failed, so we replaced it with a new 40-gallon direct-vent unit and also replaced an AC capacitor.
Boiler leak and no hot water: valves, tank and coil replaced
Huntington · Boiler Repair · September 2026
A boiler that had lost hot water and was leaking. We replaced the failed valves, the expansion tank and the leaking domestic hot water coil.
Questions people ask
Why do I have heat but no hot water from my boiler?
If the boiler makes your hot water through a coil or an indirect tank, the coil may be scaled or leaking, the tank's zone valve or circulator may have stopped, or a mixing valve may be stuck. The boiler can heat the house fine while the hot water side fails.
Why does my hot water run out fast?
On a tank, sediment, a failed lower element or a broken dip tube are common. On a tankless unit, too many fixtures at once or scale. On a boiler coil, scale inside the coil. Each has a different fix.
Should I repair or replace my water heater?
Repair a failed part on a heater that is not leaking and is under about 10 years old. Replace when the tank itself leaks or the heater is near the end of its life. We give you both prices when it is a real choice.
Need help now?
K2 answers 24/7 for homes within 15 miles of our shop at 60 S 2nd St, Unit V, Deer Park. You get a time window and the price before any repair.
Call 24/7: (631) 414-7141