What to Do When Your Boiler Breaks Down

A boiler breakdown is one of the most common emergency calls we receive, especially during winter. Knowing what to do when it happens can help you stay safe and get back up and running faster.

Check the basics first

Before calling an engineer, there are a few things worth checking. Make sure your thermostat is set correctly and hasn't been accidentally turned down. Check that your timer or programmer is set to the right schedule. Look at your boiler's pressure gauge — if it's below 1 bar, you may just need to repressurise the system using the filling loop.

Also check whether your gas supply is working. Try another gas appliance like your hob. If that isn't working either, contact your gas supplier as there may be a supply issue in your area.

When to call a Gas Safe engineer

If you can smell gas, turn off the gas supply at the meter, open windows, and call the National Gas Emergency line on 0800 111 999. Do not use any electrical switches or naked flames.

For all other boiler issues — no heating, no hot water, strange noises, error codes, or leaking — you should call a Gas Safe registered engineer. Never attempt to repair a boiler yourself as this is both dangerous and illegal if you're not qualified.

What a boiler repair typically involves

When our engineers attend a boiler breakdown, they'll diagnose the fault and explain what needs repairing before starting any work. Common issues include faulty diverter valves, broken pumps, failed PCBs, and blocked heat exchangers. Most repairs can be completed on the first visit.

Should you repair or replace your boiler?

If your boiler is over 10-15 years old and breaking down frequently, it may be more cost-effective to replace it. Modern condensing boilers are significantly more energy efficient, which means lower gas bills. We can advise on whether a repair or replacement makes more sense for your situation.

How to prevent boiler breakdowns

Annual boiler servicing is the best way to prevent unexpected breakdowns. A service checks all components, clears any buildup, and identifies potential problems before they cause a failure. We recommend booking your service in late summer before the heating season starts.