Glow-worm F75 Fault Guide for Homeowners: Meaning, Symptoms, Safety, Causes, and Prevention
The Glow-worm boiler F75 fault code indicates a problem with the pressure sensor. The two main symptoms are the error code, and interruptions to your heating and hot water supply. This fault can cause overheating and damage to your boiler. The main causes include a faulty pressure sensor, a blocked sensor, a malfunctioning pump, or low water pressure. Regular maintenance, system flushing, and pressure checks can prevent this issue. Always use a Gas Safe engineer for repairs. The next section will explain the meaning of the fault in more detail.
Meaning of the Glow-worm F75 Fault
The F75 fault code means that the boiler’s pressure sensor can’t detect a pressure change. The pressure should change after the pump starts. This failure means that the system cannot confirm water circulation. Water circulation is essential for safe operation. You would expect the pressure to increase when the pump runs. The F75 fault relates to issues with the pressure sensor or water pump.
How does the F75 fault affect the boiler operation?
The F75 fault causes the boiler to lock out, preventing it from operating. This lockout is a safety feature designed to stop the boiler from heating the water while it’s not moving. If the water is not circulating, the boiler is likely to overheat and cause damage.
Where is the pressure sensor located in a Glow-worm boiler?
In most Glow-worm boilers, the pressure sensor is on the main copper heating pipe on the left-hand side of the boiler. Accessing the sensor is a job for a Gas Safe heating engineer.
What can cause the pressure sensor to fail?
The pressure sensor can fail due to electrical faults, blockages from debris or heating sludge, or wear and tear over time. Regular maintenance and cleaning can help prevent these issues.
Symptoms of the Glow-worm F75 Fault
The main symptom of the Glow-worm F75 fault is the boiler fails to start. The display shows error code F75. You might hear the pump activate, but there is no corresponding change in pressure. This fault normally causes a lockout of the boiler, leaving you without hot water and central heating.
How To Recognise The F75 Fault on Different Types of Glow-worm Boiler
Glow-worm Combi Boilers: an error code on the digital display. You will hear the pump running, but the boiler will not fire up, leading to no heating or hot water.
Glow-worm System Boilers: an error code on the display. The boiler may make a humming sound, indicating the pump is running but not circulating water.
Older Non-digital Glow-worm Boilers: recognising the F75 fault is more challenging. You will not see a digital error code but might notice that the boiler does not start. Silence is a sign of trouble: no pump activation or water circulation means there’s a fault. Also, if there’s a manual pressure gauge, you may notice it shows no change when the boiler fires.
What to Do When Your Glow-Worm Boiler Shows the F75 Fault
When your Glow-worm boiler displays the F75 fault, follow these 4 steps. First, reset the boiler by holding down the power button for five seconds. Second, if the fault persists, check the boiler’s pressure gauge and ensure it reads between 1 and 1.5 bars when cold. Third, if necessary, top up the pressure to between 1 and 1.5 bars as per the boiler’s manual instructions. Fourth, if the boiler still does not operate, call a registered gas engineer.
Safety Disclaimer
Always follow the instructions in your boiler’s manual. Never attempt repairs beyond your expertise. Always use a Gas Safe registered engineer for any technical work or repairs.
How to Reset the Boiler?
To reset your Glow-worm boiler, press and hold the reset button for 10 seconds. The reset button is normally red. Look for some activity on the display to show you it’s resetting. You’ll normally spot a symbol flashing.
Should I Turn the Boiler Off?
Yes, if you suspect a fault or if the boiler is not functioning properly, turn off the boiler. This prevents potential overheating or further damage.
How to Top Up the Boiler Pressure?
To top up the boiler pressure, there are two taps underneath the boiler. These, along with the pipes they’re on, are known as the filling loop. Open one tap first, and then the other, to allow water to flow into the system and top up the pressure. Watch the display or pressure gauge if it’s an older boiler until the pressure reads between 1 and 1.5 bars. Close the taps and reset the boiler.
The Four Major Causes of the F75 Fault
The main causes of the F75 fault is a faulty pressure sensor, a blocked pressure sensor, a malfunctioning pump, or low water pressure. These issues disrupt the boiler’s ability to detect or maintain the correct pressure, leading to operational failures.
1. Faulty Pressure Sensor
A faulty pressure sensor is a primary cause of the F75 fault. The sensor’s role is to monitor the pressure within the boiler system. The sensor may malfunction due to electrical faults or simply from wear and tear. This failure means that pressure changes can’t be detected, leading to the F75 fault code.
2. Blocked Pressure Sensor
Blockages in the pressure sensor prevent it from accurately measuring pressure. The pressure sensor has small openings through which water flows. Over time, these openings can get clogged with debris or heating sludge. Heating sludge is a mix of rust and other particles that build up in the central heating system.
3. Malfunctioning Pump
The pump is crucial for circulating water through the heating system. The pump can’t maintain proper water flow if it has a mechanical issue. This might be stuck bearings, airlocks, or wrong speed settings. A malfunctioning pump means the system’s pressure does not change as expected when the pump activates, leading to the F75 fault code.
4. Low Water Pressure
Low water pressure can also cause the F75 fault, though it’s often linked with a faulty sensor. The boiler requires a specific pressure range to operate. If the pressure drops below this range, the system cannot function, leading to the F75 fault.
What preventative measures can avoid the F75 fault?
Preventative measures include regular maintenance by a Gas Safe engineer, periodic system flushing to remove sludge, and installing magnetic filters to capture debris. Keeping the boiler pressure at recommended levels also helps prevent this fault.
Additionally, we recommend that you keep an eye on your boiler’s pressure, especially during colder months. Ensuring the pressure remains within the recommended range can prevent faults.
Entering into a boiler service contract can simplify maintenance. It provides scheduled inspections and servicing to keep your boiler in optimal condition. It also gives some peace of mind if the worst does happen.
Disclaimer
A Gas Safe engineer should do any work beyond the instructions in the user manual. Trying to fix your boiler without proper qualifications can be dangerous. It may also void your warranty. Always seek professional help for any technical issues for your own safety. It’ll also help to keep you legal.