Troubleshooting Guide for Heat Pumps (work in progress) (By symptom (No…
for Heat Pumps (work in progress)
Low pressure on gauge
Re-pressurise using filling loop until
black needle meets red needle
No heating but hot water
Kind of heat emitter affected?
Check UFH manifold supply pipe is nice and warm (<46°C)
High temp radiators
Low temp radiators
Check heating pressure is between 1.5 and 2 bar
Thermostats battery operated?
Change battery! Not always that it shows the empty symbol!!!
Was there a power cut?
Cause of leak
Leak on primaries
Are there LED’s flashing on the FTC5 circuit board?
Check that there is power to the circuit board. There is an internal trip that may need resetting.
Check the pre-installed connectors of the Main Controller
Any visible signs of damage? Is it properly plugged in?
Turn off power to all units. Flick all dipswitches that are on to the off position and then back to the on position and vice versa for the other dipswitches.
Is there power to the outdoor unit?
The main controller will not turn on if there is no power to the outdoor unit.
Follow the Mitsubishi reset procedure
Heating OR DHW not running?
Heating not running
Turn off DHW manually.
Turn on Heating manually.
1 more item...
DHW not running
Restart the system.
Manual operation working?
Green Light flashing?
No hot water
Make sure hot water production is enabled on heat pump
Enable AUX heater for temp hot water
Hot water, luke heat?
Aux heater in AUTO mode?
Turn off outdoor + indoor
Turn on indoor
Turn on outdoor
Controller calling for HEAT/DHW?
Pumps making noise?
2 more items...
Then re-pressurise with filling loop!
Turn everything off @ the consumer board.
Then turn everything on again.
Flow Switch Open
What is the physical flow? Needs to be +16L/min
Air in system?
Pressure at 1.5-2bar?
If re-pressurised manually then reset system: Turn off/on again!
Flow switch working?
Restart system . Turn on controls first, then outdoor unit.
Check power to outdoor unit
LAN adapter lost connection!
DAIKIN Altherma COMs LED flashing? (P1P2)
heartbeat LED on LAN adapter blinking?
LAN adapter access working?
Either through app or web interface
Restart LAN adapter
Leaving water temp sensor not mounted properly (LWT)
The temp sensor affected is R1T (A1P) and connects to X5A on the PCB.
If thermostat kit for 3rd party cyl installed, check for faulty relay!
Check return temperature when changeover of 3 port valve.
Particularly after DHW satisfied, then changes over to Space Heating position (default) when there is no heating demand.
Replace sensor if required.
It's order number is 5009165.
Check for low flow and subsequent overheating on the pipe
Adjust cylinder thermostat to lower value and/or move thermostat up on the cylinder if possible.
Make sure setting allows for Legionnaires prevention (+60°C).
Make sure sensor mounted and cables connected alright
Over/ under voltage
related to indoor unit (split)
Check contacts and cables are sound connections
Check power supply is within limits of unit requirements
This is not an error, but a warning only!
Legionnaires Prevention failed (System didn't reach 60°C once a week)
Warning should clear once system achieves prevention
Make sure target hot water temp is set to 60°C.
Use controller for that.
Test manually using control panel switch to boost hot water.
Make sure high limit stat not tripped.
If so, manually reset it
Check immersion thermostat on cylinder is set high enough
Make sure immersion heater has power. Check isolator switch.
Make sure hot water is turned on. Might be turned off when in floor drying mode.
Indoor unit LT.
Flow switch activated. Water flow rate too low or blocked inlet strainer.
A16 / 18
High pressure error.
Look for sub code -01 or -12 either relating to indoor or outdoor unit
Check air flow
Check fan motor
Check high pressure sensor or switch
Check refrigerant charge. Make sure additional charge is appropriate for length of refrig pipe run.
Normally related to HT systems
Pump or Flex fault
Check filter blocked!
Check circulation pump
Communication problem between outdoor and indoor unit
Check power to indoor and outdoor unit OK
Check interconnecting cable ok
Troubleshoot on site for broken PCB
Screed Dry mode interrupted
Was there a power cut?
Reset floor drying via installer menu
Tank relay kit
Check tank thermostat has not been recently changed to too high value
Check tank relay kit is working
DAIKIN: Outdoor unit
Fan motor or PCB
Low Clima Pressure
Low Brine Outlet Temp
Communication error between indoor/outdoor unit.
Mainly due to outdoor unit switched on before indoor controller.
Turn everything off and wait 1 minute.
Then turn on indoor unit.
Go outside and turn on outdoor unit.
High pressure due to abnormal flow rates.
If MELcloud fitted, have Mitsubishi take a look remotely.
Check for blocked strainer/filter.
Check MCS bypass is open!
Check all other valves are open as intended.
Check for air in system. Purge if required.
Check heating system pressure between 1.5 and 2 bar.
The system should still operate with pressure as low as 0.6 bar.
Low primary circuit flow rate detected
by flow sensor / flow switch
Check operation of flow switch.
Replace if necessary
Very likely: Blocked strainer.
Check and clean and re-pressurise if required.
See Error L3
Problem with outdoor unit.
Check flow rates
Check for power cuts
Outdoor fan motor or PCB
Check fan obstructed?
Check fan motor unplugged?
Check main PCB for supply voltage to fan motor.
Replace fan or PCB
Check for loose connections on the controller
Restart the system
Circulation water temp overheat protection
Check flow rate. May be reduced.
Water circulation pump malfunction.
Request code 540
High discharging temperature
Defective outdoor controller
Turn the power off and check if U3 is displayed when the power is turned ON again.
When U3 is displayed, refer to “Judgment
and action” for U3.
Defective operation of linear
expansion valve. Check operation of expansion valve.
Check linear expansion valve.
Refer to "9-5. HOW TO CHECK THE
In the case of the unit does not
restart :Detection temp. of thermistor
(TH33) > 95°C
Overheated compressor operation
caused by insufficient refrigerant.
Check intake super heat.
Check leakage of refrigerant.
Charge additional refrigerant.
Refrigeration circuit issue
Check refrig circuit
Check refrig expansion valve operation
Check for leaks on refrig circuit
DHW overheat protection
Check immersion heater and its contactor
Brine temperature is at lower level, triggering alarm.
Check flow rates and pressure of borehole/loops.
Check brine low temp setting. If antifreezed, temp can be lower.