Technical data

33
6. Fault Finding
Many faults which occur on commissioning are found to be due to incorrect wiring or setting up, therefore
it is recommended that a thorough check is carried out should there be a problem.
Symptom Possible Cause Action
Blank display on software controller No power supply Check wall mounted electrical isolator switch
or call electrician
Controls MCB tripped Call electrician to investigate cause
There is no call from the time-clock or
thermostat for heat pump operation
Programme time-clock according to manu-
facturer’s instructions
Compressor not running but display
reading temperature near setpoint
Heat pump is up to temperature No fault
Display flashes fault code tP Low water pressure in the ground or heating
system side due to pipe relaxation or other
pressure loss.
Check the pressure gauges below the two
water pumps. The pressures should be be-
tween 1 and 2 bar. If below this, the pressure
needs to be increased above 1.8 bar
To increase the pressure in either circuit, the
cold fill valve will need to be opened. The
Ground cold fill is provided with every Vent-
Axia heat pump, and is found on the right
hand side of the heat pump, underneath.
The heating distribution system should have
it’s own fill point.
Display flashes fault code HP Overheat warning. No or low flow around
heating distribution circuit because of air in
water pump, or stuck water pump impellor,
or heating distribution system valves/
actuators closed.
HP can also be temporarily displayed when
the heat pump reverts from DHW to space
heating mode.
Bleed the heating distribution system pump
within the heat pump, using the schrader
valve above the pump. (See Fig 28).
Check that the water pumps are operational
and spin the impellors. ( See section 5.3 )
No action
Display flashes fault code LP Low gas pressure in machine. Can occur
simultaneously with an A1 alarm.
Can occur temporarily on first start up when
unit is new or after a long period out of use.
Insufficient antifreeze added and heat pump
frozen.
Check that the water pumps are operational
and spin the impellors (see section 5.3)
If symptom persists outside of the two listed
circumstances, contact Vent-Axia Technical
department.
No action
Allow heat pump to defrost and add the
correct antifreeze quantity.
Display flashes fault code A1 Freeze protection system activated. Low or
no water flow on the ground (cold) side of
the machine. Can also occur after many
months of running in very cold weather.
Check antifreeze has been added and unit
commissioned correctly.
Check that the water pumps are operational
and spin the impellors (see section 5.3)
Ensure no flow restrictions and wait approxi-
mately 4 hours (with the machine turned off)
for automatic reset.
Display flashes fault code E1, E2, E3 or E4 Loss of contact with probes inside heat
pump. E4 could be loss of contact with
weather compensation sensor
Refer to Vent-Axia Technical department