Boiler Repair & Service in Toronto & the GTA

Boiler faults are usually in the water side rather than the fire side: a waterlogged expansion tank, a seized circulator, air in the loop, a failed zone valve or a slow leak dropping system pressure. Chasing the burner when the problem is a flooded expansion tank is the most common misdiagnosis we get called in behind.

Annual service on a boiler is not the same job as a furnace tune-up. We check system pressure against static head, test the relief valve, verify the low-water cutoff on applicable systems, bleed and balance the loops, inspect the heat exchanger and confirm combustion. A well-serviced boiler routinely outlives two forced-air furnaces.

Boilers fail quietly compared with forced-air systems. Instead of stopping outright they lose output — one zone goes lukewarm, radiators need bleeding more often, or the system pressure creeps up and dumps through the relief valve. By the time a boiler stops entirely, the underlying fault has usually been developing for a season or more, which is why we check circulator operation, expansion tank charge and system pressure on every visit rather than only the reported symptom.

Hydronic systems also punish neglect in ways air systems do not. Oxygen ingress through an undersized or waterlogged expansion tank corrodes the heat exchanger from inside, sludge settles in low points and blocks circulation, and a partially closed zone valve will imitate a failing circulator perfectly. We test the system as a loop, not as a box on the wall.