Boiler & Gas Guides
Practical step-by-step guides for London homeowners — from repressurising your boiler to what to do in a gas emergency. Written by our Gas Safe registered engineers.
If you smell gas right now: Do not use electrical switches. Leave the property immediately. Call the National Gas Emergency Service: 0800 111 999 (free, 24/7). See our full guide below.
What to do when your boiler breaks down
Step-by-step guide for London homeowners on what to do immediately when their boiler stops working.
- 1
Check the basics first
Check that your gas supply is on (try another gas appliance like the hob). Check the boiler's pressure gauge — it should read 1–1.5 bar. Check the thermostat is set above the current room temperature and the programmer is on.
- 2
Look for an error code
Most modern boilers display a fault code on the digital display when something goes wrong. Note down the code and look it up in your boiler manual, or tell us the code when you call — it helps us diagnose the fault before we arrive.
- 3
Try a manual reset
Many boilers have a reset button (often marked with a flame symbol or "Reset"). Hold it for 3–5 seconds. The boiler may restart and fire up. If it locks out again after reset, do not keep trying — call an engineer as there is an underlying fault.
- 4
Check the fuse box
Check your fuse box (consumer unit) to see if the boiler circuit has tripped. If the breaker is in the "off" position, try switching it back on. If it trips again immediately, do not reset it — call an engineer.
- 5
Call a Gas Safe engineer
If none of the above resolves the issue, call a Gas Safe registered engineer. Do not attempt to open the boiler casing or work on gas components yourself — it is illegal and dangerous. Call Anmol Boilers on 07984 499661 for a same-day emergency response across London.
Still having trouble? Our Gas Safe engineers are available 24/7 across all London boroughs.
How to repressurise your boiler
How to safely repressurise a combi or system boiler using the filling loop when pressure has dropped below 1 bar.
- 1
Turn off the boiler and let it cool
Switch the boiler off and wait 10–15 minutes for it to cool down before repressurising. Never repressurise a hot boiler.
- 2
Locate the filling loop
The filling loop is a small flexible braided hose with one or two valves, usually located underneath the boiler. Some boilers have an internal filling loop — check your manual if you cannot find it.
- 3
Connect the filling loop if external
If the filling loop is not already connected, attach both ends to the boiler's filling points. Ensure both ends are firmly connected to prevent leaks.
- 4
Open the valves slowly
Slowly open both valves (turn them so the slot aligns with the pipe direction). You will hear water entering the system. Watch the pressure gauge carefully.
- 5
Stop at 1.2–1.5 bar
Watch the pressure gauge on the boiler. Close the valves as soon as the needle reaches 1.2–1.5 bar. Do not overpressurise — above 2.0 bar the pressure relief valve will activate and release water.
- 6
Remove the filling loop and restart
Once the valves are closed, disconnect the filling loop (if external) and store it safely. Switch the boiler back on. If pressure continues to drop regularly, call an engineer — it indicates a leak in the system.
Still having trouble? Our Gas Safe engineers are available 24/7 across all London boroughs.
How to bleed a radiator
How to bleed air from a radiator to restore full heat output when the top of the radiator is cold.
- 1
Turn the heating on and identify cold radiators
Run the heating for 10–15 minutes then check each radiator. If a radiator is cold at the top but warm at the bottom, air is trapped inside and it needs bleeding.
- 2
Turn off the heating and let radiators cool slightly
Switch the heating off and wait 20–30 minutes before bleeding. The water will still be warm but not scalding. Never bleed a radiator when the heating is running.
- 3
Locate the bleed valve
The bleed valve is the small square or hexagonal nut at the top corner of the radiator. You will need a radiator bleed key (available from any hardware shop for under £1).
- 4
Open the valve and release the air
Hold a small container or cloth under the valve. Insert the bleed key and turn it slowly anti-clockwise (about a quarter to half turn). You will hear a hissing sound as air escapes. Keep the key in position and hold the cloth ready.
- 5
Close when water appears
As soon as a steady stream of water (not air) emerges, immediately close the valve by turning the key clockwise. Do not overtighten. Wipe up any drips.
- 6
Check boiler pressure afterwards
Bleeding radiators can cause the boiler pressure to drop. Check the gauge after bleeding — if it has dropped below 1 bar, repressurise using the filling loop.
Still having trouble? Our Gas Safe engineers are available 24/7 across all London boroughs.
How to reset your boiler after a lockout
How to safely reset a boiler that has locked out and is displaying an error code, and when to call an engineer.
- 1
Note the fault code
When your boiler locks out, it will usually display a fault code or flash a light. Write down or photograph the code — it identifies the fault type and will help an engineer diagnose the problem if the reset does not work.
- 2
Wait before resetting
Some boilers require you to wait a short period (30–60 seconds) before a reset will take effect. Check your boiler manual for the correct wait time for your model.
- 3
Press and hold the reset button
Locate the reset button (usually marked with a flame icon or the word "Reset"). Press and hold it for 3–5 seconds until you hear the boiler attempt to fire. Some boilers reset with a key or dial rather than a button.
- 4
Observe the restart
The boiler should attempt to ignite. Listen for a click and a whoosh as the burner lights. The display should show normal operating information. If it locks out again within a few minutes, do not keep resetting.
- 5
Call an engineer if lockout repeats
A boiler that repeatedly locks out has an underlying fault that needs professional diagnosis. Common causes include a faulty ignition lead, blocked condensate pipe, low gas pressure, or a failed component. Call a Gas Safe engineer — do not attempt to open the boiler yourself.
Still having trouble? Our Gas Safe engineers are available 24/7 across all London boroughs.
How to read your gas meter
How to read a gas meter accurately for submitting readings to your energy supplier and monitoring usage.
- 1
Locate your gas meter
Gas meters in London properties are typically found in a meter cupboard near the front door, under the stairs, in the kitchen, or in a communal meter room (for flats). Ensure the area is well lit before reading.
- 2
Identify your meter type
Most meters are either digital (LCD display) or dial-type (with 5 clock faces). Smart meters display consumption automatically. The reading method differs for each type.
- 3
Read a digital meter
For a digital meter, simply read the numbers on the display from left to right, including any leading zeros. Ignore numbers after the decimal point and any numbers shown in a different colour or in red. Note down the figure shown in cubic metres (m³) or hundreds of cubic feet (ft³).
- 4
Read a dial meter
For a dial meter, read the dials from left to right. When a pointer is between two numbers, record the lower number. When a pointer appears to be exactly on a number, record that number but check the next dial — if the next dial has not passed zero, reduce your reading by one.
- 5
Submit your reading
Submit the reading to your energy supplier online, via their app, or by phone. Regular readings ensure accurate bills and help you monitor your gas consumption. If your reading is significantly higher than expected, check for appliance faults or call us to check for leaks.
Still having trouble? Our Gas Safe engineers are available 24/7 across all London boroughs.
How to check if a gas engineer is Gas Safe registered
How to verify that a gas engineer is legally Gas Safe registered before allowing them to work on your gas appliances.
- 1
Ask the engineer for their Gas Safe ID card
Before any gas work begins, always ask the engineer to show you their Gas Safe ID card. Every registered engineer must carry this card by law. They should show it willingly — if they refuse or claim they do not need one, do not let them work on your gas appliances.
- 2
Check the card details
The card should show: the engineer's name and photo, their unique registration number, the appliance types they are qualified to work on (listed as symbols on the back), and the card's expiry date. Ensure the card has not expired.
- 3
Verify on the Gas Safe Register website
Go to GasSafeRegister.co.uk and use the "Check an engineer" tool. Enter the engineer's Gas Safe registration number or the company's details to confirm they are registered and their qualifications are current.
- 4
Check the symbols match your appliances
On the back of the ID card, there are symbols showing which types of gas work the engineer is qualified for (domestic boilers, gas fires, cookers etc). Make sure the symbol for your appliance type is listed.
- 5
Keep a record
Note down the engineer's Gas Safe registration number and the date of the work for your records. As a landlord, you are required to keep gas safety records for at least 2 years.
Still having trouble? Our Gas Safe engineers are available 24/7 across all London boroughs.
What to do if you smell gas in your home
Emergency steps to take immediately if you smell gas inside your property.
- 1
Do not use electrical switches
Do not turn any electrical switches on or off, do not use your mobile phone inside, do not press doorbell buttons, and do not use any other electrical devices. A spark could ignite the gas.
- 2
Extinguish all naked flames
Put out any candles, cigarettes or open flames immediately. Do not attempt to light any appliance.
- 3
Open windows and doors
Open all windows and doors to ventilate the property and allow the gas to disperse safely. Leave internal doors open as you move through the property.
- 4
Turn off the gas at the meter
If it is safe to do so, turn off the gas supply at the emergency control valve (ECV) next to your gas meter. Turn the handle so it is at 90 degrees (crossways) to the pipe to close the supply.
- 5
Leave the property immediately
Get everyone out of the property, leaving the door open behind you. Do not go back inside to collect belongings.
- 6
Call the National Gas Emergency Service
From outside the property, call the National Gas Emergency Service on 0800 111 999 (free, available 24/7). Do not return inside until the gas emergency operator tells you it is safe to do so.
National Gas Emergency Service: 0800 111 999 (free, 24/7). Call from outside your property.
Need a Gas Safe Engineer?
Available 24/7 across all London boroughs for emergency and planned work.