A puddle under a boiler gets attention fast. It could be a small drip at a valve or a crack in the boiler itself. The first minutes decide whether you have a repair or a flood.
This guide explains what to shut off, how to read the leak and what the repair options look like.
If you smell gas, leave the house and call 911 or PSE&G at 1-800-880-7734 before anything else.
Shut It Down Safely
- 1Switch off the power
Use the emergency switch or the breaker for the boiler.
- 2Close the feed valve
The water feed line adds fresh water to the system. Close it to stop refilling.
- 3Do not drain the whole system
Draining can let in air and rust. Wait for the plumber unless water is pouring out.
- 4Catch and photograph
Place a pan under the leak and take photos.
Where Boiler Leaks Come From
| Where | Likely cause | Repair |
|---|---|---|
| Pressure relief valve | System pressure too high or valve worn | Replace the valve, check the expansion tank |
| Circulator pump flange | Failed gasket | Replace the gasket or pump |
| Pipe fitting or union | Loose or corroded joint | Tighten or replace |
| Zone valve | Worn packing or body | Replace the valve |
| Boiler body or section | Cracked or corroded heat exchanger | Usually replacement |
Most leaks are in the first four rows, and those are repairable. A leak from the boiler body is a different story, because the heat exchanger cannot be patched safely.
Want a plumber on the way? The line is open all day and all night.
☎ Call (732) 466-1098Repair Or Replace
A boiler older than its expected service life, with a leaking section and rising repair costs, is a candidate for replacement. A newer unit with a bad valve is a repair. See boiler repair for what we handle and what needs a heating contractor.
Ask for both prices and for the age of the unit. A new boiler is a major purchase, and some utilities offer rebates on efficient models.
Utility Work On North Brunswick Streets
PSE&G announced it would replace aging cast-iron gas pipes on roughly 22 North Brunswick streets from October 2023 through 2024. Wheeler Road, Hobart Road, Kearny Drive and Harding Avenue were among the streets listed.
If your street had gas work and the boiler stopped, ask the utility whether your service was shut off or reconnected. Utility work does not cause a water leak, but it can cause a no-heat call that looks like a boiler failure.
Water-Side Versus Combustion-Side Problems
A boiler has two halves. The water side includes pipes, pumps, valves and the expansion tank. The combustion side includes the burner, the flue and the gas or oil train. A leak is a water-side problem, and a plumber handles it.
If the leak came with soot, a burning smell or a yellow flame, that is a combustion-side problem. Switch the boiler off and call a heating contractor. A good plumber says so, and does not guess.
Questions To Ask About A Replacement Quote
Ask every contractor
- What size boiler do you recommend and how did you size it?
- Will the existing radiators and piping work with the new unit?
- Is the quote for the boiler, the install and the removal of the old one?
- Who handles permits and inspections?
- What does the warranty cover on parts and on labor?
A good contractor has answers and puts them in writing.
Pressure Numbers To Watch
Most residential hot water boilers run at a modest pressure when cold and a bit higher when hot. A gauge that creeps up with every heating cycle points to a failing expansion tank. A gauge that keeps dropping points to a leak.
Write the cold reading on a piece of tape near the gauge. A quick glance each month tells you when something has changed.
Bleeding Radiators And Re-Pressurizing Safely
After a repair, a boiler needs to be refilled, brought to the right pressure and bled of air. Radiators that stay cold at the top need a little air released through the bleed valve until water appears.
Do this slowly and watch the gauge. Overfilling raises pressure and can open the relief valve. If you are not sure, let the plumber do it while on site. According to PSE&G, a gas smell means leaving the building and moving at least 350 feet away before calling for help.
Prevent Winter Surprises
Bleed radiators early in the season, check the pressure gauge monthly and look for stains on piping. A system that needs water often is leaking somewhere.
A leak in an unheated space can freeze and burst a pipe. If water is running, see burst pipe repair. We serve North Brunswick, New Brunswick and Edison.
Local questions answered
A slow drip is usually not an emergency. A growing puddle, steam or a gas smell is. Switch off power and call.
A failed expansion tank or feed valve is the usual cause.
PSE&G replaced aging gas pipes on many streets in 2023 and 2024. Ask the utility if your service was affected.
A cracked heat exchanger is generally not repairable. Replacement is the safe answer.
We handle the water side. When the burner needs work, we tell you if a heating contractor is needed.
Ready to talk to a plumber? The line is open all day and all night.
☎ Call (732) 466-1098