Heat Line
Fault Codes

Listed below are the common Heat Line fault codes as described by the boiler manufacturer along with a possible cause.

Heat Line Fault Codes

Table 1. Most common Heatline faults based on 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

Table 2 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
 
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