We have created a guide to one of the most common faults we get asked about.
Nobody wants their hot water supply or radiators to stop working. Unfortunately, incidents like this do sometimes occur and are often caused by a drop in boiler pressure. Depending on the cause, it is sometimes possible to correct a drop or increase in boiler pressure yourself, while other problems may require additional assistance.
Check out our guides below for our most popular boilers.
ATAG Boilers
Error code 118 could mean that the system pressure is too low and you may see that the system pressure gauge indicates that the pressure in the system is below the 0.8 – 1 bar pressure.
The pressure within the system can be seen in two ways. There is an analogue gauge, which can be found under the bottom left hand side of the boiler or you can find a digital reading from the digital display of the control panel. The digital display can be seen by pressing the Eco button for 6 seconds and then scroll through (tap + plus button) to ‘A6’ which will display the water pressure.
The system pressure should be set around 1.0 – 1.2 bar when the water is cold.
When the system is working and the water is heated up within the system, water expands due to heat and you may see the pressure rise up to around 1.8 – 2.4bar when hot. This is normal as water system pressure increases due to heat.
So we are looking for the system pressure to be set around 1.0 – 1.2 bar when the water is cold.
Turn off any clocks and room thermostat for heating or hot water controls.
On the iC and iC Economiser Plus models, to re-pressurise the system you will find a filling loop (copper ‘U’ shaped tube with two nuts at each end) on the underside of the boiler or a metal braded flexible hose external of the boiler on the pipework with one or two tap connections at the either end of the filling loop, which is normally used on iS range of boilers as well.
On the underside of the boiler there is a filling loop position where this copper ‘U’ shaped tube will connect between the small blue and black isolation valve connection. If not in position, remove the caps and install as shown and tighten up the nuts hand tight.
The taps should be opened a quarter of a turn and the water will start to refill the system (water should be heard filling the system). You should see the pressure gauge rise back up between 1 bar and 1.2 bar pressure and then stop filling. The error code 118 will stop and the boiler will now operate. If the error code 118 is still active, fill up the system a little more but not over 1.4bar.
The display should now show ‘OK’, which means the pressure level is correct and the boiler is ready to operate.
(If you do fill the system too much and the pressure gauge is too high, just bleed water from a radiator until the pressure on the gauge goes down to below 1.2 bar).
Alpha Boilers
Error code E10 could mean that the system pressure is too low and you may see that the system pressure gauge indicates that the pressure in the system is below the 0.8 – 1 bar pressure.
How to Resolve Low Pressure?
Should your boiler be suffering from low pressure and you are confident it is not as a result of a leak, then it is safe to repressurise your boiler system. If you are unsure about undertaking this task yourself, we would recommend hiring a Gas Safe Registered engineer to look at the system for you. However, it is also possible to tackle this problem on your own, as long as you stick to the following quick steps: Turn Off Your Boiler First, ensure your boiler is switched off before you begin to repressurise it. If possible, you should try and let the system cool for between four to six hours before starting this process.
Find the Hose
Next, check to see whether your boiler has an external filling loop. If it does, you may need to attach a braided filling hose here. Attaching a filling loop will enable you to add more pressure to the system. Some boilers have an internal filling loop, or a similar device used for the same function. If you are unsure, it is always best to refer to the manufacturer’s handbook for guidance.
Open the Filling Valves
Using either the installed tap handles or a screwdriver, start to open the filling valves on the boiler pipe work. As you turn the valves, you should begin to hear the sound of water running. Whilst doing this, keep an eye on the pressure gauge and ensure that the pressure is rising.
Close the Valves
Once the pressure gauge hits a reading of one bar it is time to close the valves off again. Try to not let the reading creep above one, as the pressure will still continue to increase slightly once the valves have been closed.
Switch the Boiler Back On
Wait for the pressure reading to settle, which can take a couple of minutes. Once it has, ensure that the reading is within a safe level of between one and one and a half bar and proceed to switch the boiler back on.
Ideal Boilers
Error code F1 could mean that the system pressure is too low and you may see that the system pressure gauge indicates that the pressure in the system is below the 0.8 – 1 bar pressure.
To Top up the system:-
Ensure both A & B handles (blue) are in the closed position (as shown below)
Remove the plug and cap and retain.
Connect the filling loop to the Domestic Hot Water (DHW) inlet and tighten. Also, ensure that the other end of the filling loop is hand tight.
Turn the Domestic Hot Water (DHW) Inlet A blue handle to the horizontal position.
Ensuring no leaks are seen, gradually turn the filling loop handle (blue) B to the horizontal position.
Wait for the pressure gauge to reach 1 to 1.5 bar.
Once pressure is reached turn valves A & B back to the closed position.
Disconnect the filling loop, replace the cap and plug. Note there can be some water spillage at this point.