What does it mean if my boiler is condemned?

If a Gas Safe engineer tells you your boiler is "condemned", it means they've found a safety problem serious enough that the boiler shouldn't be used until it's put right. It doesn't always mean the boiler has to be scrapped. Sometimes a repair makes it safe again. But until that's done, it must stay switched off, however cold the house is.

This post explains what the warning labels mean, why it's dangerous to switch the boiler back on, what happens next for homeowners and landlords, and how to decide whether to repair or replace. Never try to reconnect a boiler or remove a warning label yourself.

"Condemned" isn't the official word

Engineers often say "condemned", but the formal process is called the Gas Industry Unsafe Situations Procedure. Under it, a Gas Safe engineer who finds a problem puts it into one of three categories:

• Immediately Dangerous: the appliance is a danger to life or property right now, for example because it's leaking gas or letting carbon monoxide into the home. With your permission, the engineer will disconnect it from the gas supply and attach a "Danger Do Not Use" label.

• At Risk: there are one or more faults that could become dangerous, such as a damaged flue or poor ventilation. With your permission, the engineer will turn it off and label it so it isn't used.

• Not to Current Standards: the appliance isn't unsafe, but it doesn't meet today's standards. You'll be advised about it, but it can usually stay in use.

The engineer should give you a written warning notice that says which category applies and why. Keep it, as you'll need it for the next step.

Why you mustn't switch it back on

A boiler that's been made safe can be tempting to restart, especially in winter. Don't. The fault that was found, whether it's a gas leak, a damaged flue or poor combustion, is still there. Using it could mean carbon monoxide in the home, which has no smell, or a gas leak.

The law also says gas appliances that are known to be dangerous mustn't be used. If you refuse permission for an Immediately Dangerous boiler to be disconnected, the engineer can report it to the gas emergency service, which can disconnect the supply.

Make sure you have a working carbon monoxide alarm near any gas appliance. If you ever smell gas, open doors and windows, don't use light switches or anything that could cause a spark, turn the gas off at the meter if you can safely reach it, leave the property and call the National Gas Emergency Service on 0800 111 999.

Can the boiler be repaired?

Often, yes. Some faults that lead to a warning label are fixable:

• a flue that's come apart or isn't sealed properly

• a gas leak on a fitting or the pipework

• poor ventilation in the room or cupboard

• a part that's causing the boiler to burn badly

Other faults are much harder to put right on an older boiler, such as a cracked heat exchanger (the part that passes heat from the burning gas into your heating water), parts that are no longer made, or a flue that can't be brought up to standard where it is. In those cases, replacing the boiler is usually the safer and better-value choice.

You're entitled to ask a different Gas Safe engineer for a second opinion before deciding, and the warning notice will help them see what was found. Our boiler repair service starts by checking the fault for ourselves and explaining the options.

If you're a landlord

A boiler labelled unsafe in a rented home needs dealing with quickly. You must make sure the gas appliances you provide are safe, so the boiler can't be used by your tenants until it's repaired or replaced and checked again. It's worth giving your tenants temporary heaters and a clear idea of when it will be fixed.

Once the work is done, the boiler should pass its next landlord gas safety check, and you'll get an updated record for your tenants.

We recently helped a landlord in this exact position. Another engineer had condemned the boiler at their rental property in Harlow. We replaced the boiler, ran a new gas pipe and fitted wireless heating controls so the heating could be managed more easily. You can see the Harlow boiler replacement on our projects page.

What happens if it needs replacing

If a new boiler is the answer, the engineer will look at where it can go, whether the flue route and gas pipe are suitable, and the right size and type for your home. A new boiler sometimes needs a larger gas pipe than the old one, as in the Harlow job. Our post on how to tell when it's time for a new boiler covers the signs that point to replacement.

While you wait, keep warm safely. Use electric heaters rather than any gas appliance that's been labelled, and don't use cookers or ovens to heat the room.

Getting your heating back safely

S&G Plumbing & Heating Solutions is Gas Safe registered and repairs and replaces boilers for homeowners and landlords. If your boiler has been labelled unsafe, we'll check the fault, explain whether it can be repaired, and if it can't, plan a replacement. Find out more about our boiler installation service, or get in touch to book a visit.