Cold radiators, a boiler that keeps locking out, or an old cast iron unit that's finally done? If you're searching for boiler repair near me in St. Catharines, ExpressFlow Plumbers handles same-day boiler repair, annual service and new combi and condensing boiler installation for homes and commercial buildings.
Same-day
boiler repair
Combi & condensing
installation
Home & commercial
boiler service
No heat tonight?
We're on call 24/7. What to check first
Boiler brands we service & install
Most boiler repair calls in St. Catharines come down to one of three failures. Here's what they look like and what we do about them.
The boiler is silent, or it runs but the radiators stay cold. Typical causes are low system pressure, a failed circulator pump, a stuck zone valve or a faulty control board.
What we do: test pressure, pump, valves and controls, then fix the failed part, usually in the same visit.
An older boiler's pilot won't stay lit, or a newer one flashes an error code and locks out. Common culprits are a worn thermocouple, dirty flame sensor, failed igniter or gas valve fault.
What we do: read the code, test the ignition and gas train, and restore safe operation.
Water under the boiler, rust streaks, or pressure that keeps dropping. On cast iron boilers this can mean a cracked section; on modern units, a leaking heat exchanger.
What we do: find the exact source. A valve or fitting gets repaired; a cracked section usually means replacement.
A boiler that fails on a January night isn't something that can wait until Monday. Our emergency boiler service runs around the clock, and no-heat calls with small children, older residents or freezing pipes at risk go first.
Other urgent plumbing problems? Our 24 hour emergency plumber in St. Catharines handles those too.
Thermostat: set to heat, a few degrees above room temperature, with fresh batteries.
Power: the boiler's breaker and service switch are on.
Pressure: a home boiler usually reads about 12–15 psi when cold. Much lower means a leak or a fill problem.
Reset once, not repeatedly. Repeated lockouts are a safety feature pointing to a real fault.
Check your carbon monoxide detector. If it's alarming, or you smell gas, leave the house now and call 911 and Enbridge Gas at 1-866-763-5427 from outside. Every home with a gas boiler needs a working CO alarm.
Most boilers last 10–15 years. Well-kept cast iron units can run longer, but their efficiency falls far behind modern models. We'll tell you honestly which option makes sense.
Whether it's a new boiler installation in a renovated home or a boiler replacement for a cast iron unit that has heated the house for decades, we size the new boiler to your home's real heat loss, not just the old boiler's label. An oversized boiler short-cycles, wastes gas and wears out early.
We remove the old unit, install the new boiler with proper venting and controls, then fill, purge and balance the system so every radiator heats evenly. New boilers are covered by the manufacturer's warranty, and we walk you through what it covers before the job starts.
Most popular
One compact unit for heating and on-demand hot water, so there's no separate water heater tank. A great fit for most homes with one or two bathrooms. Popular models include Navien, Rinnai and IBC combi boilers.
Highest efficiency
Recovers heat from exhaust gases for efficiency of 95% AFUE or more. Ideal for larger homes, often paired with an indirect hot water tank. Brands include Viessmann, NTI and IBC.
Older homes
Replacing an old cast iron boiler with a modern one cuts gas use noticeably. For large radiator systems that need a robust boiler, Weil-McLain remains a common choice.
01
Heat loss check
Sizing based on your house, not guesswork.
02
Clear quote
Options explained before any work starts.
03
Installation
Old unit removed, new boiler, venting and controls.
04
Startup & balancing
Safety checks and even heat in every room.
Many St. Catharines homes in Port Dalhousie, Merritton, Western Hill, Glenridge, Grantham and downtown still heat with cast iron radiators and hot water. These systems last for generations when they're looked after, but they need attention.
Separate hot water tank acting up? See our water heater repair service.
A yearly boiler service before the heating season catches small problems before they leave you without heat, and most manufacturers require it to keep the warranty valid. Each visit includes:
A boiler breakdown in an office, restaurant or apartment building can leave people without heat and disrupt daily operations. Our commercial boiler repair service in St. Catharines covers heating problems, leaks, pressure loss, circulation pump failures and faulty controls. We diagnose the cause and explain the repair options before work begins.
We also provide commercial boiler maintenance, including checks of pumps, valves, thermostats and safety controls. If an older unit needs frequent repairs, we can assess whether commercial boiler replacement makes more sense for the building.
Looking for commercial heating repair near me? Our team responds to emergency commercial boiler repair calls 24/7 across St. Catharines. Larger gas-fired equipment is handled by appropriately qualified G1-certified technicians, helping property managers plan repairs while minimizing downtime.
Common boiler problems involving gas, electric and combi boilers, from emergency no-heat calls to repairs, maintenance and replacement.
"Our gas boiler stopped heating the radiators on a freezing January morning. The technician checked the ignition system and found a faulty flame sensor. He replaced the part and tested the heating before leaving. Glad we called instead of trying to reset it again."
Colin M.
Old Glenridge
January 22, 2026
Gas Boiler Repair
"Our combi boiler was giving us hot water but no heat in the house. The plumber diagnosed a problem with the diverter valve and explained the repair before starting. Both the taps and radiators are working properly now."
Melissa R.
Port Dalhousie
February 12, 2026
Combi Boiler Repair
"The pressure on our boiler kept dropping, and we had to top it up every few days. They found a leaking connection near the expansion tank and repaired it. The pressure has stayed steady since. Good service and clear communication."
Trevor H.
Merritton
March 6, 2026
Low Boiler Pressure Repair
"We needed boiler repair in St. Catharines after our electric boiler stopped responding to the thermostat. The technician checked the controls and found a failed relay. He explained what had happened and got the heating system working again."
Andrea B.
Grantham
April 9, 2026
Electric Boiler Repair
"Our old boiler was nearly 20 years old and needed repairs every winter. The team explained the replacement options and installed a new high-efficiency unit. They checked the radiators, controls and water pressure before finishing."
Gregory L.
Western Hill
September 18, 2026
Boiler Installation & Replacement
"I was searching for boiler repair near me when our heating stopped working on a Sunday evening. They checked the circulation pump and found it wasn't running properly. The technician replaced the faulty component and tested the radiators before leaving."
Natalie F.
Martindale
October 11, 2026
Emergency Boiler Repair
Answers to what St. Catharines homeowners and property managers ask us about boilers.
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