Common Heat Line boiler error codes

With over four decades of experience since our establishment in 1974, Maintracts Services has become a leading name in the heating industry.

Our team of expert heating engineers has gained extensive knowledge and expertise in dealing with Heat Line boilers, offering a wide range of services including installation, maintenance, and repair. In today’s blog post, we will be diving into a topic that every Heat Line boiler owner or technician should be familiar with common Heat Line boiler error codes.

These error codes can be perplexing, but fear not! We are here to provide you with valuable insights into what these error codes signify and how to effectively troubleshoot them.

Whether you’re a homeowner, a landlord, or a heating professional, join us as we demystify the world of Heat Line boiler error codes and help you ensure optimal performance and reliability for your heating system.

Heat Line Fault Codes

This table below will show the most common Heat Line faults based on an error code message:

Fault code	Description	Solution
F00	Flow heating temperature sensor fault	Verify the sensor’s connections. Verify the wiring harness. Verify the sensor
F01	Return heating temperature sensor fault	Verify the sensor’s connections. Verify the wiring harness. Verify the sensor
F10	Flow heating temperature sensor fault	Verify the sensor’s connections. Verify the wiring harness. Verify the sensor
F11	Return heating temperature sensor fault	Verify the sensor’s connections. Verify the wiring harness. Verify the sensor
F20	Overheating fault	Verify the operation of the pump. Verify the wiring harness. Verify that the fl ow and return heating isolation valves are open
F22	Water pressure of the installation	Fill the installation. Purge the installation. Verify the pump connections. Verify the flow and return heating sensor connections. Verify that there are no leaks
F23	Maximum temperature difference reached between return and flow heating	Verify the flow and return heating sensor connection. Verify the pump speed
F24	Water circulation fault	Verify that the fl ow and return heating isolation valves are open
F26	Fault in gas valve motor	Verify the gas valve connections. Verify the operation of the gas valve. Verify the operation of the condensate pump
F27	Flame detection fault	Verify the flame detection electrode. Verify the main board. Verify the igniter unit
F28	Ignition fault	Verify the return gas circuit (gas valve open). Verify the observe the flame picture and Verify the CO setting. Verify the igniter unit connections. Verify the state of the electrode
F32	Incorrect air pressure	Verify the entire flue system. Verify the fan’s electrical connections
F49	EBUS voltage fault	Verify that the eBus controls are fitted and wired correctly
F61-67	Fault in the main board	Verify the main boards connections. Verify the main board. Verify the appliance DSN number is correct. Reset the appliance
F68	Fluctuation of flame signal	Verify the return gas circuit (gas valve open). Verify the observe the flame picture and Verify the CO setting. Verify the igniter unit connections. Verify the state of the electrode .
F70	User interface incompatible with the main board	Verify that the appliance DSN code on the screen matches the product code of the nameplate. Verify the boards reference
F71	Flow heating temperature sensor fault	Verify the sensor connections. Make sure that the sensor is clipped to the tube
F72	Permanent temperature difference between flow and return heating sensors	Verify temperature sensors connections. Replace faulty sensors
F73-74	Heating circuit pressure sensor fault	Verify the sensor’s connections. Verify the sensor
F76	Thermal fuse fault	Verify the fuses connections. Replace the heat exchanger
F77	Fault in gas valve motor	Verify the gas valve connections. Verify the operation of the gas valve. Verify the operation of the condensate pump
F83	No water in the installation: the temperature doesn’t increase when the burner is lit	Fill the installation. Purge the installation. Verify the pump connections. Verify the fl ow and return heating sensor connections. Verify that there are no leaks
F84	Permanent temperature difference between flow and return heating sensors	Verify temperature sensors connections. Replace faulty sensors
F85	Flow and return heating sensors fault	Verify temperature sensors connections
F86	Underfloor heating contact fault	Verify the sensor connections. Verify that the sensor is connected to the main board and the shunt is removed
Err	User interface fault	Verify connection from user interface PCB to main PCB. Replace user interface

This second table below will show central heating and hot water functionality fault finding:

Fault	Action	Solution
No hot water	Is the central heating? Yes	Replace flow meter or/and D.H.W. sensor
No hot water	Is bar LED illuminating? Yes	Re-pressurize system
No central heating	Is there overheat LED illuminating? Yes	Replace overheat thermostats
No central heating	Is pump running? No	Check wiring / connections mains voltage
No hot water and no central heating	Open a hot tap to create a demand – is there a spark at the ignition electrode? Yes	Replace gas supply, pressure or gas valve
No hot water and no central heating	Open a hot tap to create a demand – is there a spark at the ignition electrode? No. Is fan running? Yes	Replace air pressure switch or overheat sensor
No hot water and no central heating	Are LEDs on? No	Replace user interface PCB
No hot water and no central heating	Is fan running? No	Replace low water pressure switch