Gas boilers use hot water or steam to heat indoor air. When the thermostat senses a drop in temperature, it triggers the boiler to turn on. The gas-fired boiler heats water and sends it to your home through the radiators. The heated water warms the indoor air and circulates back to the boiler for heating. If your boiler is providing little or no heat, you will need to troubleshoot it. Below are four potential reasons your gas boiler isn't heating your home.

Faulty Thermostat

If your boiler isn't heating your home when it's on, the first component to check is the thermostat. The thermostat has sensors that detect indoor temperatures and signal the boiler to turn on. Therefore, if the thermostat is faulty, it won't sense temperature changes or signal your boiler. If you use your boiler for water heating, check your hot water fixtures. If you have hot water, then chances are you have a faulty heater thermostat. Repair or replace the thermostat to restore indoor heating.

No Pilot Light

Gas boilers have a pilot light, a small flame that acts as the ignition source for your boiler. The pilot light should never go out, and when it does, your boiler won't work. When you turn on the heater, there will be no ignition source to light up the gas. Therefore, check whether your boiler's pilot light is on. The pilot may go out due to a cracked heat exchanger, old and worn heating system, faulty gas valve, or faulty thermocouple.

You can try to relight your pilot light by following the manufacturer's instructions on your boiler. However, if the light goes out again, you need to get the boiler checked for the above issues.

Low Water Level

Your boiler should maintain a specified water level at all times. If the water level falls below the lowest permissible level, it will trip the burner and shut down the heat input. This safety feature helps prevent overheating, which can cause a dry fire accident. Unfortunately, boilers lose some water during operations. You need to regularly check the water levels and refill the boiler to prevent equipment damage and fire hazards.

Scale Buildup

Mineral deposits in the water can gradually accumulate in your boiler and heat exchanger. They form scale buildup, which acts as an insulator and heat retardant. The buildup reduces the boiler's heating efficiency. If your system is no longer heating air as fast as it used to, you need to check the boiler for scale buildup. Flush and clean the boiler to remove mineral deposits. In the future, consider using water softeners and de-mineralizers to keep scale-forming minerals out of your heating system.

Contact a professional contractor for a proper diagnosis and boiler repair.