Error E44

Safety first:

- Do not work on gas appliances unless you are a Gas Safe registered engineer. If you suspect a gas problem, turn off the gas supply at the meter and call a Gas Safe engineer.

- Turn the boiler off and isolate the electrical supply before removing panels or touching internal components. Allow the system to cool before opening any valves or pipework to avoid scalding.

- If you find water leaking onto the floor or electrical components, switch off the electrical supply to the boiler and the mains water and call an engineer.

Initial quick checks a homeowner can do:

1. Look at the pressure gauge on the boiler. For a cold system aim for about 1.0–1.5 bar (1.3 bar is common target). If it is below 1.0 bar the boiler may lock out and show E44.

2. Check for obvious visible leaks under/around the boiler, at radiators, radiator valves, visible pipework and the overflow/PRV discharge pipe (often a small plastic pipe that exits the property or runs to a waste drain).

3. Check that the filling loop (a braided hose or small pipework often below the boiler) is closed and its isolation valves are fully shut. If the filling loop is left open it can cause other problems; if it’s open it should be closed after topping up.

4. If you recently bled radiators, it is normal for pressure to drop; you will usually need to top up afterwards.

If pressure is low and there are no obvious leaks — how to top up (general steps):

1. Ensure the boiler is off and cool. Locate the filling loop under the boiler (a braided flexible hose or a small pipe with two shut-off valves). Some systems have an integrated keyed/isolator type filling valve.

2. Confirm both filling-loop valves are closed before you start. If there is a removable flexible loop, make sure it is correctly attached.

3. Open the first filling-loop valve slowly, then open the second valve slowly. Watch the pressure gauge while you do this.

4. Stop when the gauge reaches about 1.2–1.3 bar (acceptable range 1.0–1.5 bar cold). Do not over-pressurise the boiler. If you overshoot, you can release pressure by bleeding a radiator slightly until the gauge drops to the desired level.

5. Close both filling-loop valves fully and, if applicable, remove and stow the flexible loop or ensure any isolation keys are reinserted/secured.

6. Turn the boiler back on and press the reset button if the boiler has locked out. Observe the boiler for normal operation and re-check pressure after the system has run and cooled.

Diagnostics if topping up does not solve the problem or pressure keeps falling:

1. Re-check for leaks thoroughly: inspect radiators, radiator valves, pipework, boiler base and beneath the PRV discharge. Leaks are the most common reason for pressure loss and need repairing by an engineer.

2. Check the PRV discharge pipe for recent water — a dripping or discharged PRV indicates a failed PRV or overpressure event and needs a Gas Safe engineer to inspect/replace.

3. If pressure falls slowly over days or reverts to low after topping up, suspect a system leak or a faulty auto-fill valve/filling loop. Ensure the filling loop is fully closed; if the auto-fill valve is leaking it will need replacement by an engineer.

4. If pressure rises excessively when heating (more than around 0.2–0.3 bar above cold pressure), or the pressure varies wildly, suspect a faulty expansion vessel. An expansion vessel failure normally requires an engineer to test and replace or re-pressurise it.

5. If you have repeatedly lost pressure four times in 24 hours or get E24/E67 style messages in addition to E44, stop attempting further DIY and call an engineer as a persistent fault indicates a leak or failing component.

When to call a professional:

- Call a Gas Safe registered engineer if you find a leak, water under the boiler, water coming from the PRV discharge, or if pressure keeps dropping after topping up.

- Call an engineer for PRV, expansion vessel, pressure switch or internal boiler component faults. Any repairs involving gas valves, internal plumbing on the boiler, or replacement of sealed components must be carried out by a qualified engineer.

- If you are unsure at any stage or uncomfortable performing the topping-up procedure, stop and call a Gas Safe engineer.

Aftercare and checks:

- After any topping up or repair, run the heating, let the system warm and then cool and re-check the pressure to ensure it remains stable.

- Keep a log of pressure readings and any times you have to top up; this helps an engineer diagnose intermittent leaks or component faults.

Important note: Some Keston documentation and different model variants sometimes list similar codes with slightly different meanings (for example sensor faults). On a C40/C55 E44 is commonly used for low water pressure. If you suspect a sensor/electronics fault rather than actual low pressure, an engineer will need to test the pressure switch and thermistor wiring and the control PCB.