7 Signs Your Boiler Needs Repair Before Winter

Loud knocking or a rumbling like a boiling kettle usually points to scale or sludge on the heat exchanger, or trapped air in the system. Left alone, it wears the boiler out faster and makes it less efficient.

Cold spots at the top of a radiator usually mean trapped air, which can often be bled. A radiator that is cold at the bottom or not heating at all can mean a stuck valve or a circulation problem that needs a technician.

Any pooling water or drips at the boiler, pipes or relief valve should be looked at promptly. Small leaks get bigger, and corrosion inside the unit is hard to reverse.

A pilot light that will not stay lit, or a burner that lights and shuts off, can come from a dirty flame sensor, a failing thermocouple, poor venting or a gas supply problem. If you ever smell gas, leave the building and call your gas utility from outside.

A healthy gas burner flame is mostly blue. A lazy yellow or orange flame can signal incomplete combustion, which can produce carbon monoxide. Make sure working CO detectors are on every floor and have the boiler inspected.

If your usage is climbing with no change in habits or weather, efficiency is dropping. A tune-up often recovers some of it. A boiler that is very old may cost more to run than a replacement would.

Cast-iron boilers can last a long time, but when repair calls become yearly events, ask for an honest repair-versus-replace opinion that includes the cost of the repairs so far and what is likely to fail next.

Have the boiler serviced before the first cold stretch, not during it. Check that your thermostat, water pressure gauge and visible pipes look normal, and keep the area around the boiler clear.