Air source heat pump troubleshooting

If the system develops a fault, a red light will be displayed under the screen and a message will appear on the display with the alarm cause. It will also display an alarm number which relates to the issue.

To reset the alarm, slide the power button to the left and the screen will go blank. Then slide it back to its previous location – the display module will now restart and the heat pump unit will now try to return to normal operation.

If the fault code re-appears then you should contact our Technical Support Team.

Alarm 220 High pressure alarm

This is due to low flow rate of system water passing through the heat pump heat exchanger causing it to overheat this is linked to:

• Low water pressure in the system (1 bar of water pressure is required)
• Isolation lever valves is in a closed position
• The zone valve, on the cylinder coil feed pipe, being in a closed position
• Check for an air lock in the system pipework
• Check for a failed charge pump
• Check for a blocked Strainer (this should be cleaned annually as part of a yearly service)
• Check the charge pump valves have not been left in a closed position.

Alarm 301 Com error Slave 1-8

Slave 1-8 indicates the heat pump with the error code, if more than one heat pump has been installed.

This alarm is caused by the indoor SMO display module not receiving signal data from the heat pump unit.

• Check the main fuse board for the house; checking the supply to the heat pump unit has not tripped out
• Check the rotary power switch outside, by the heat pump, is not turned off
• Perform these steps: Power down the heat pump unit outside for a minimum of 10 minutes then restart it. This will often clear the issue. You will also need to power off and on the indoor display module when restarting
• A damaged cable between heat pump and SMO display unit could be the cause.

If the system develops a fault, this will be shown on the Nibe display screen, and a red light will be displayed in the top right hand corner of the enclosure. A message will appear on the display as to the alarm cause – it will also display an alarm number which relates to the issue.

To reset the alarm, select the message on the screen marked as “I want to see more about info about the alarm”, then select the message “Reset alarm and try again”.

The display module will now restart and the heat pump unit will now try to return to normal operation.

If the fault code re-appears then you should contact our Technical Support Team.

Alarm 229 High pressure alarm

This is due to low flow rate of system water passing through the heat pump heat exchanger causing it to overheat this is linked to:

• Low water pressure in the system (1 bar of water pressure is required)
• Isolation lever valves is in a closed position
• The zone valve on the cylinder coil feed pipe is in a closed position
• Check for an air lock in the system pipework
• Check for a failed charge pump
• Check for a blocked Strainer (this should be cleaned annually as part of a yearly service)
• Check the charge pump valves have not been left in a closed position.

Alarm 271 Com error Slave 1-8

Slave 1-8 indicates the heat pump with the error code, if more than one heat pump has been installed.

This is caused by the indoor SMO display module not receiving data from the heat pump unit.

• Check the main fuse board for the house, ensuring the supply to the heat pump unit has not tripped out
• Check the rotary power switch outside, by the heat pump, is not turned off
• Perform these steps: Power down the heat pump unit outside for a minimum of 10 minutes then restart it. This will often clear the issue. You will also need to power off and on the indoor display module when restarting
• A damaged cable between heat pump and SMO display unit could be the cause.

If the system develops a fault, this will be shown on the Panasonic display screen, and a option to reset the alarm will be given.

If after resetting an alarm code on the Panasonic controller, the alarm keeps recycling back up onto the display screen straight away, power off and on the outdoor heat pump. This will clear the issue.

If the fault code re-appears then you should contact our Technical Support Team.

H62 flow switch abnormality – activated after 6mins

High pressure issue – check: cylinder zone valve is open; system water pressure (should be minimum of 1 bar); filter valve for dirt; and positioning of lever valves.

H20 Water pump abnormality

Possible grit in the charge pump or a failed pump unit.

H98 High pressure overload

Progressive build-up of pressure, causing the unit to overheat. Recommended steps would be:

1. To check the filter for clogging
2. Check the lever valves have not been knocked half closed.

F12 Pressure switch activated

This alarm would indicate a complete blockage of flow in the system. Recommended steps would be:

1. Check the zone valve going into the hot water cylinder is open
2. Check the filter for clogging
3. Check the lever valves have not been knocked half closed.

If the system develops a fault, this will be shown on the main Hitachi controller. Normally it will display ‘TEXT **°C’. If a fault is detected it will display ‘FAUL *’.

The number tells the engineer what the fault relates to. Every so often the controller will self-check and you may see it display ‘FAUL 0’. This shows there are no faults and the system is operating properly.

‘FAUL 9’ means it has detected a problem with the heat pump. This is commonly air in the system, or a blocked filter, causing a high-pressure alarm in the air source heat pump. Other fault codes between 1 and 12 refer to sensors and the wireless thermostat controller.

If a fault code appears, the first action is to switch the mains power to the Hitachi controller off and on. This will re-set the unit.

If the fault code re-appears then you should contact our Technical Support Team.

High pressure issues

This is due to low flow rate of system water passing through the system. Check the Y strainer filter unit, fitted to the return pipe work to the heat pump, is clear of dirt and debris – this is commonly installed with lever valves fitted each side of the strainer to allow it to be isolated off to allow for cleaning. This strainer should be checked annually at servicing.

Failed zone valves

This type of system has multiple zone valves installed one for hot water production and one for heating production the way the system is designed to operate only one zone valve should be open at a time – Check that each zone valve is opening and closing when the system switches between operation functions.

Lack of system water pressure

Check the expansion vessel pressure gauge – the gauge will have a black needle to show the current value. This system will require a minimum of 1 bar of system pressure.