Is Your Boiler Not Turning On? Causes and Fixes

Although some may view boilers as outdated, they remain a reliable heating source for millions of American homes. An estimated 9 million homes have boiler systems, particularly in the Northeast, where about 60% are found. Known for their quiet operation and energy efficiency, boilers provide even, consistent heating.

However, like all HVAC systems, boilers aren’t invincible; they can occasionally break down and fail to turn on. Is your boiler not turning on? HVAC.com explores common reasons your boiler might not start and offers solutions to restore heating in your home.

Reasons Your Boiler Won’t Start

Thermostat Issues

If your boiler won't turn on, it’s always a good idea to start at the thermostat. Make sure the thermostat is set correctly, and replace the batteries if needed. If it’s still not functioning, contact an HVAC professional to recalibrate or replace the thermostat.

No Power

A power issue is another common reason a boiler may not start. A tripped circuit breaker or blown fuse can disrupt the power to the boiler. Check the electrical panel for a tripped breaker and reset it; if the fuse is blown, replace it. If power issues continue, reach out to a licensed electrician to investigate.

Low Water Pressure

A drop in water pressure can prevent an HVAC boiler from starting because the system relies on adequate pressure to function properly. Insufficient pressure may trigger safety mechanisms that shut down the boiler to prevent damage or overheating. Additionally, low pressure can disrupt the flow of water, inhibiting the boiler’s ability to heat effectively.

Safety Lockout Mode

Most boilers have safety features that engage and shut the system down when a fault is detected. Check the control panel for error codes or alerts; once the underlying issue is resolved, you may need to reset the boiler to return it to normal operation.

Some common reasons your boiler may go into safety lockout mode include:

• Gas supply issues
• System blockages
• Ignition failure
• Low water levels
• Low water pressure
• Blocked flue or ventilation issues
• Faulty flame sensor
• Clogged air filter

Pilot Light or Ignition Failure

For gas boilers, if the pilot light is out or the ignition system fails, the boiler won’t ignite. Follow the manufacturer’s instructions to safely relight the pilot. If it does not stay lit, the thermocouple may need to be replaced, or a technician should inspect the ignition system.

Faulty Pump

A malfunctioning circulation pump can prevent hot water from moving through the system, causing the boiler to shut down. Listen for unusual sounds from the pump or check for power. If the pump is not operating, it may need to be repaired or replaced.

Routine Maintenance Can Help Prevent Issues with Your Boiler

To prevent issues with your boiler and extend its lifespan, it’s important to ensure regular maintenance is performed. For homeowners, there are some DIY tasks that can help keep your boiler running efficiently and prevent breakdowns.

Start by checking the pressure gauge; it should typically be between 1 and 2 bars. If it’s low, you may need to add water to the system. Also, make it a habit to bleed radiators at the beginning of the heating season to remove trapped air, which can improve efficiency. Finally, inspect for leaks and listen for any unusual noises, and contact a professional if you notice any of these issues.

It's recommended to have your boiler inspected by a professional at least once a year. During this service, a technician will perform a thorough check, including inspecting the flue and venting systems, cleaning internal components, and checking for gas leaks. They’ll also test safety controls and ensure that the boiler is operating efficiently. Maintenance helps prevent breakdowns and extend the lifespan of your boiler, ensuring it operates safely and efficiently for years to come.