How to Reset a Boiler

If your boiler has stopped working and you're left without heating or hot water, a reset might be all it needs to get going again. Modern boilers are built with safety features that shut them down when they detect a fault, but in many cases, the problem is temporary—such as a power cut, low pressure, or frozen condensate pipe.

In this guide, we’ll walk you through how to reset a boiler safely, when it’s appropriate to do so, and when it’s time to call a professional. If you’re based in Guildford, Godalming, or Milford, our heating engineers are here to help with fast, local support.

What Does Resetting a Boiler Do?

Resetting a boiler clears the fault code displayed on the control panel and attempts to restart the system. It's a common step when:

Your boiler locks out due to a temporary issue
You've resolved the cause of the error (like topping up the pressure or thawing a pipe)
There's no hot water or heating, and the display panel suggests a reset is needed

Boiler reset functions are built-in safety mechanisms that allow you to restart your system once a minor issue has been resolved.

Common Reasons Why Boilers Lock Out

Before you reset, it’s worth understanding why your boiler has shut down. Common causes include:

Low water pressure
Power cuts or supply interruptions
Airlock or pump faults
Frozen condensate pipe in cold weather
Sensor or ignition failures
Flame detection errors

Your boiler will usually display an error code, flashing light, or message to help identify the fault. Check your manufacturer’s manual or the brand’s website to interpret the code before you reset.

How to Reset a Boiler (Step-by-Step)

Although the exact steps can vary by boiler make and model, the process is generally the same for most combi, system, and heat-only boilers. Always refer to your boiler’s user manual if you’re unsure.

Step 1: Identify the Reset Button

Look for a button marked “reset” on the boiler’s control panel. On some models, this may be a dial or symbol, often accompanied by a red or flashing light when there's a fault.

Step 2: Press and Hold the Button

Press and hold the reset button for 5 to 10 seconds, or until the boiler responds. You may hear a click or see the display screen change as the boiler restarts.

Step 3: Wait for the Boiler to Reignite

Once reset, your boiler will attempt to relight the burner and resume normal operation. This can take a few minutes. You may hear the fan starting or the ignition sequence beginning.

Step 4: Check for Operation

Check that your boiler has resumed normal operation by:

Listening for the boiler firing up
Checking that the fault code or warning light has cleared
Confirming that radiators and hot water are heating correctly

If everything seems normal, you’ve successfully reset your boiler.

Important Safety Notes

Never reset a boiler repeatedly if it keeps locking out. This indicates a persistent issue that needs professional attention.
Don’t attempt to reset if you smell gas, suspect a leak, or see signs of electrical damage. In these cases, turn off the boiler, ventilate the area, and call an emergency engineer immediately.
Do not open the boiler casing or attempt internal repairs unless you’re Gas Safe registered.

If your boiler fails to restart after one reset attempt or continues to display a fault code, get in touch with a qualified heating engineer.

When to Call a Heating Engineer

Resetting a boiler is only effective if the issue is minor or already resolved. If your boiler continues to:

Lock out after resetting
Display the same fault code
Make loud or unusual noises
Leak water or lose pressure
Fail to provide heat or hot water

…it’s time to call in a professional. Boiler faults involving gas, water, or electrics can quickly escalate and should always be handled by a Gas Safe registered engineer.

Need Boiler Help in Guildford, Godalming or Milford?

Whether your boiler won’t reset or you’re unsure what’s causing the fault, our experienced engineers are here to help. We provide reliable boiler diagnostics, repairs, and servicing across Guildford, Godalming, and Milford.

Call us today to arrange a visit or fill out our contact form for a fast response. We’ll get your heating and hot water back up and running safely.