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Boiler Won’t Turn On: Your Troubleshooting Checklist Before Calling for Service

September 29, 2023

Whether it’s the beginning of the heating season or the middle of winter if your boiler fails to start up, don't worry – you can take several troubleshooting steps to address the issue before calling in a professional.

In this article, we'll present a brief checklist covering the following topics to help you get your heating back on track:

  • Check the boiler power supply
  • Verify thermostat settings
  • Examine the pilot light

By following the steps we outline, you may be able to identify and resolve the problem without the need for professional service. However, we'll also discuss who to call for expert help if you require further assistance.

Additionally, we'll highlight the significant benefits of preventative boiler maintenance, which can help you avoid such issues in the future and ensure your boiler operates efficiently and reliably. Get ready to tackle boiler problems head-on and restore warmth and comfort to your home!

Is your boiler not starting up?

If you need help from a professional, reach out to the expert technicians at Ranshaw Plumbing & Heating. We provide all our prices upfront because we value honesty and transparency. Plus, with over 60 years of experience, you can rest easy knowing that our work is dependable. Call us at (718) 767-0707 or schedule online today.

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Check the Power Supply

The first thing you need to do if your boiler isn’t turning on is to check your boiler’s power supply. Look at your circuit breaker to make sure none have tripped. If you have a fuse box, check for a blown fuse. If you see either, you’ll want to identify what caused the issue in the first place. Otherwise, it may just happen again. You can also find the power switch for the boiler itself and make sure it didn’t get turned off. Usually, this wall switch should be pretty close to the boiler.

Verify Thermostat Settings

The next item on the troubleshooting checklist is your thermostat. First, you should ensure the batteries in your thermostat still have power. If you're unsure, try replacing the existing batteries with new ones.

If the batteries are okay, next, you should ensure the thermostat settings are correct. First, make sure the thermostat is set to heat. Next, check the temperature setting. If the temp is set too low, the boiler will not turn on, and you’ll be stuck with cold radiators and an unheated home. If nothing happens when you turn the temperature up, or if your boiler appears to be cycling frequently, there may be another issue with the thermostat, or your problem lies elsewhere.

Examine the Pilot Light

Another potential culprit for your malfunctioning boiler is the pilot light. The pilot light is a small gas flame that ignites a more powerful gas burner that heats the water inside your boiler. If your pilot goes out, the burner will not operate, and your boiler will not start up.


One reason for your pilot light going out could be strong drafts. This is easy to recognize as you would be able to easily relight the pilot light, and it would only go out in extreme winds.

Open the cover panel on the front of your boiler. If there is a small flame, your pilot light is functional.

Relighting the Pilot Light

Steps for relighting a boiler pilot light:

  1. Make sure the gas supply is shut OFF
  2. Make sure the gas valve switch is shut OFF
  3. Remove the covers
  4. Move the gas valve switch to PILOT
  5. Open the gas supply valve
  6. Push and hold the pilot button
  7. Light the pilot
  8. Hold the pilot button for 30 seconds, then release
  9. Move the gas valve switch to ON
  10. Replace covers

If your pilot keeps going out due to a persistent draft, fixing it permanently could require changes to your boiler room setup or the boiler itself.

Thermocouple Issues

This can be a complex area to address, so you may want to contact a professional at this point.

A broken thermocouple can cause your pilot light to go out even without gas issues. The thermocouple is a metal rod that directly interacts with the pilot light. If it senses the pilot light is no longer functional, it shuts off the gas to prevent gas build-ups. Unfortunately, thermocouples can malfunction, shutting off the gas at odd moments. If the thermocouple is defective, this is something you’ll need a professional to replace.

Benefits of Preventative Boiler Maintenance

The best thing you can do to ensure your boiler is operating trouble-free is to perform preventative maintenance. Scheduling annual service with a skilled technician can go a long way toward preventing major issues that seem to spring up out of nowhere. This could save you tons of money and the inconvenience of being stuck without heat when you need it most. Beyond that, your safety is at risk if serious problems exist in the system.

Have professionals inspect your boiler so that your boiler is one less thing you have to worry about.

Don't Wait in the Cold Any Longer - Take Action Now!

If you do need expert assistance, we've got you covered. Contact Ranshaw Plumbing & Heating, and we’ll get it right the first time, guaranteed. We service and repair most steam and hot water boiler brands and models and there’s nothing we haven’t seen. Call us at (718) 767-0707 or schedule online. Don't wait – Act now and experience the comfort you deserve!

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