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Online support - NIBE GSHPs

If you’re still experiencing any problems, please contact our technical support team via techsupport@nu-heat.co.uk or give them a call on 01404 540745(available from 8am to 5pm, Monday to Friday).

NIBE 1145-1245 alarm troubleshooting

TL/TB alarm 52
Occurs when built in immersion increases flow temp too high (usually after legionella purge). Has to be manually reset. Turn the heat pump off, remove the cover and reset button using smallest electrical screw driver available in hole FD1-SF2 on pg17 of NIBE 1145 installer manual.
If reccurring, it could be a flow issue. If towel rails are fitted on DHW primary coil, ensure signal wire to DHW zone valve is taken from terminal 11 on 1145 PCB as per A14 docking drawings pg 3of4, and not terminal 7 as it was on old drawings.

Motor Protection alarm / Phase fault
Possible unsteady voltage has been supplied to the unit MP trips to protect compressor. Has to be manually reset by removing the front cover and locating rotary switch FB1 on pg17 of NIBE 1145 installer manual. The switch should be in the horizontal position.

HP Alarm
High pressure in refrigerant caused by poor flow on waterside of heat exchanger in heat pump so it over heats in effect.
Things to check include: dirty inline filter on return to heat pump, air in system (check silver air scrubber), are all valves fully open?

No Heating or Hot water – No Alarm logged
Compressor symbol (blue piston symbol) showing on menu 3.1 and on page 19/24. If hot gas, liquid line and suction gas temps are all room temperature then possible soft start failure; NIBE to attend.

Ground loops / LP alarms
0bar pressure in ground loops is ok as long as Glycol is present in vessel. It’s best to be running at 1bar in summer, this will drop though in winter as brine cools.

If no pressure and no Glycol, it could be a leak – most probably on a connection in manifold pit. Installer to investigate.

LP alarms common with leaks – LP alarm occurs due to low pressure in refrigerant due to poor flow on brine side of heat exchanger, effectively cooling it right down.

Things to check as well as leaks: check inline strainer on ground loops is clean and check all valves are fully open, brine pump running so brine in/out temps have 3-5°C differential.


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