- Banging, knocking, or rumbling noises Have it checked
Banging or rumbling (often called kettling) usually points to scale or sediment on the heat exchanger that makes water boil unevenly, or to trapped air or...
- No heat or no hot water Address promptly
No output can come from a tripped low-water cutoff, a failed igniter or pilot, a faulty thermostat or aquastat, a stuck circulator pump, or a safety...
- Relief valve discharging or pressure too high Address promptly
A discharging pressure-relief valve is a safety device doing its job. Frequent discharge points to a waterlogged expansion tank, a failing fill valve, or...
- Visible leaks, water, or corrosion Address promptly
Water pooling at the base, weeping valves, or rust on the vessel and piping signals seal or fitting failure, or corrosion of the pressure vessel itself....
- Pilot or burner will not stay lit Have it checked
Repeated burner lockouts often trace to a dirty flame sensor or thermocouple, gas supply pressure, a venting problem, or a safety control shutting the...
- Yellow or sooty flame, or soot around the boiler Address promptly
A healthy gas flame is mostly blue. A lazy yellow flame or soot can indicate incomplete combustion, which raises the risk of carbon monoxide.
- Boiler keeps shutting off on low water Address promptly
The low-water cutoff shuts the burner off when water drops too low, protecting the boiler from dry firing. Repeated trips usually mean water is being lost...
- Pressure gauge reads unusually high or low Have it checked
Pressure that drifts outside the normal range can come from a failing fill valve, an expansion tank that has lost its air charge, a leak, or a stuck...
- Water heater relief valve dripping or tank leaking Have it checked
A dripping temperature and pressure relief valve often means excess pressure from thermal expansion or an overheating control. A leaking tank usually...
- Boiler turns on and off constantly (short cycling) Have it checked
Rapid on-off cycling wastes fuel and wears components. Common causes are an oversized boiler, poorly set controls, a failing sensor, or low flow through...
- Expansion tank waterlogged or leaking Have it checked
An expansion tank absorbs the change in water volume as the system heats. When it waterlogs or loses its air charge, pressure spikes and the relief valve...
- Boiler inspection or certificate is overdue Have it checked
This is a compliance gap rather than a malfunction, but an expired certificate can mean penalties, a violation on the building, or an insurance problem....
- Boiler failed inspection or received a defect notice Address promptly
A failed inspection means defects were found that have to be corrected, documented, and in many places re-inspected or affirmed within a set window....
Describe it in your own words
Not sure which one it is? The interactive Problem Solver can match a plain description to the likely problem and show the local rules for your building.
Open the Problem Solver