Heat Line Boiler Error Codes

At Maintracts, we know how stressful it can be when your boiler suddenly stops working, especially in the middle of a chilly London evening. That’s why we’ve created this detailed, easy-to-follow guide to help you understand Heat Line boiler error codes, what they mean, and what actions you can take. Whether you're troubleshooting an annoying F22 fault or dealing with a sensor malfunction, this blog will walk you through it all, clearly and confidently. 

We’ve worked with thousands of homes and businesses across London since 1974, and boiler issues are something we handle every single day. Our expert heating engineers are fully trained in Heat Line boilers and ready to help when you need us. 

Need immediate help? Call us today on 020 8682 2244 or email us at info@maintracts.co.uk.  

 

 

What Are Heat Line Boiler Error Codes?

Heat Line fault codes are diagnostic messages displayed on your boiler's screen to alert you to a fault or malfunction. These codes help pinpoint issues such as a flow temperature sensor fault, gas valve motor failure, or even low system pressure alerts. Each code has a specific meaning and solution, ranging from minor resets to the need for professional repairs. 

By understanding what these codes mean, you’ll know when it’s a simple fix or when it’s time to contact a Gas Safe registered engineer like us. 

 

Heat Line Boiler Fault List – Common Codes Decoded

Here’s a helpful Heat Line boiler fault list to guide you through some of the most frequent issues: 

1. F00 / F01 – Flow or Return Sensor Fault

This error suggests a flow sensor or return sensor malfunction. It could be a faulty sensor, a poor connection, or a break in the wiring. We can replace faulty sensors and test wiring to restore regular operation. 

2. F20 – Boiler Overheat Fault

An F20 code points to boiler overheat detection. This happens if the system temperature rises too high, often due to a pump isolating valve fault or circulation issue. It’s crucial to turn off the boiler and call an engineer right away.

3. F22 – Low Water Pressure

A common issue indicates low system pressure. You may need to repressurise the boiler by adding water through the filling loop. If this doesn’t help, there might be a leak or a faulty pressure sensor. 

Want to learn more about this? We’ve also created guides on Glow-Worm boiler error codes and Ideal Logic boiler fault codes for additional support. 

4. F24 – Pump Failure or Air Lock

This means poor water circulation, potentially due to a blocked condensate pump, airlock, or pump failure. In such cases, components may need replacing. 

5. F26 – Gas Valve Motor Failure

This fault indicates an issue with the gas valve operation—either it's stuck or faulty. Don’t try to fix this yourself; it involves handling gas, and only certified engineers should carry out the repair. 

6. F27 – Flame Detection Fault

When your boiler can’t confirm flame presence after ignition, it flags an F27 flame detection issue. Possible causes include a faulty igniter electrode, gas supply issues, or a blocked flue. 

7. F28 – Ignition Fault

This means your boiler failed to ignite. It could stem from ignition sequence failure, a problem with the main control board, or gas supply problems. Our engineers can test components and restore functionality. 

8. F32 – Fan or Air Pressure Switch Error

The air pressure switch ensures that combustion gases are safely expelled. If this fails, it causes an F32 error. It might also point to a faulty fan or blockages in the flue system. 

9. F70 – eBus Fault or Interface Error

This fault usually involves communication errors between the boiler's eBus control system and internal components like the main control board. 

10. F76 – Thermal Fuse Triggered

When the boiler's thermal fuse trips, it usually signals that the heat exchanger has overheated. This is a safety-critical fault and requires professional inspection and replacement. 

11. F86 – Underfloor Heating Error

Some Heat Line models support underfloor heating, and F86 can indicate issues in that zone—possibly linked to sensor calibration or circulation errors. 

 

Heat Line Boiler Troubleshooting Tips

Before calling us, you can try a few basic checks: 

• Check the pressure: If the pressure is below 1 bar, top it up to 1.5 bar using the filling loop. 
• Reset the boiler: Some faults may clear after a reset (check your manual for steps). 
• Check gas and power: Ensure the gas supply and electricity are on. 
• Bleed radiators: Air in the system can cause circulation issues. 

However, never attempt to repair internal components yourself. For faults involving gas valves, sensors, or the igniter electrode, it’s vital to call a qualified heating engineer. 

If you're also dealing with other brands, we’ve created helpful guides for Baxi boiler error codes, Ariston boiler error codes, and Biasi boiler fault codes. 

 

When To Call Maintracts For Boiler Repairs

You should call us if: 

• The same fault keeps reappearing. 
• You hear unusual noises. 
• The boiler switches off frequently. 
• There's no hot water or heating. 

You see error codes related to gas valve motor failure, flow temperature sensor faults, or eBus system errors. 

We offer professional boiler repair in London with rapid response times, transparent pricing, and no hidden fees.