Baxi boiler showing E118 in Birmingham? It means the system water pressure is too low. How to check it, how to top it up, and what it means if it keeps happening.
The heating system water pressure is too low for the boiler to run.
Most Baxi boilers want around 1 to 1.5 bar with the heating cold.
Open slowly, watch the gauge, close when it is in range, then reset the boiler.
A slow drip at a valve is one of the most common reasons the pressure keeps falling.
Water dripping from the copper pipe outside means the relief valve is letting go.
A vessel that has lost its air charge makes the pressure rise and fall too far.
Yes, following the boiler manual. It is routine maintenance and most filling loops are designed for it.
Once or twice a year is not unusual. Every week or two means there is a fault.
Very likely. That pipe comes from the pressure relief valve, and water from it means pressure is being released, often because of an expansion vessel problem.
The boiler stops itself to prevent damage, which is what E118 is. Running it repeatedly at low pressure by resetting is not a good idea.
Yes. Valves, joints, the relief valve and the expansion vessel are checked in turn until the cause is found.
Ask to see the Gas Safe ID card when they arrive. The back lists exactly which appliances that engineer is qualified to work on, and the number can be checked on the Gas Safe Register.
On many Baxi combi boilers, E118 means the water pressure in the heating system has fallen too low for the boiler to run safely. The boiler stops to protect itself, and nothing more will happen until the pressure is back where it should be.
The first step is to look at the pressure gauge or the reading on the display. With the heating cold, most Baxi boilers want somewhere around 1 to 1.5 bar. If it is well below that, the system needs topping up through the filling loop, the small flexible hose or key under the boiler, following the steps in the boiler manual. Open it slowly, watch the gauge, and close it when the pressure is in range.
Topping up once is normal maintenance. Topping up every week is a symptom. Water is leaving the system somewhere, and in Birmingham's older terraces and semis the usual places are a weeping radiator valve, the pressure relief valve letting water out through the copper pipe on the outside wall, or an expansion vessel that has lost its charge and lets the pressure swing too far each time the system heats up.
If you have topped up and E118 returns within days, or you can see water dripping from the copper pipe outside, it is time for an engineer to find the cause rather than keep refilling.
A photo of the boiler badge and the display on WhatsApp tells us the make, the model and often the likely part before anyone sets off. If you smell gas, leave the house, do not touch switches and ring the National Gas Emergency line on 0800 111 999 from outside.
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