If your boiler has shut off, a careful restart is sometimes all it needs. The key word is careful, boilers burn gas or oil, and safety comes before getting the heat back. Here’s how to do it sensibly, and when to stop.
Before anything: if you smell gas or rotten eggs, do not touch any switches. Leave the building and call 911 or your gas utility from outside. This guide is for a boiler that simply cut out, with no gas smell and no visible leak.
Step by step
- Check the thermostat. Set it to heat and a few degrees above room temperature so the boiler has a reason to fire.
- Confirm power. Make sure the boiler’s service switch is on and the breaker or fuse for the boiler hasn’t tripped. Reset a tripped breaker once.
- Check pressure or water level. On a hot-water system, the pressure gauge should read in its normal range (often around 12–15 psi cold). On a steam system, the sight glass should show water around the middle. If a hot-water system is very low on pressure, that’s usually a call, not a DIY top-off.
- Find the reset button. Many boilers have a single reset button, often on the burner or control (sometimes behind a small cover). Press it once and wait for the unit to attempt ignition.
- Give it a minute. The boiler may go through a purge and ignition sequence. Listen for it to fire and stay running.
When to stop and call
- The boiler lights, then locks out again. Repeated lockouts mean the safety system is catching a real problem, stop resetting.
- You’ve pressed reset once and it won’t fire at all.
- There’s water leaking, a burning or oily smell, or soot around the unit.
- You have a steam boiler with an empty sight glass and you’re not sure how to feed it safely.
- Any gas smell, that’s always leave-and-call-911 first.
Why one reset only? Each failed ignition can leave unburned fuel in the combustion chamber. Hitting reset over and over risks building up that fuel, which is genuinely dangerous. One try is safe; a pattern of lockouts is a job for a licensed tech.
If the restart doesn’t hold, don’t spend the night cold. Call and we’ll connect you with a licensed NYC boiler technician who can find out why it won’t stay running.