Nibe 60 Fault Code: Causes, Fixes & Repair Costs
What does the Nibe 60 fault code mean?
Alarm 60 (Low HTF Out) activates when the outgoing Heat Transfer Fluid (brine) temperature drops below the minimum permitted threshold. The heat pump responds by locking out the compressor to protect the system. This fault is specific to ground source heat pump installations that use a brine or glycol-based ground loop circuit — it does not apply to Nibe air source models.
General guidance only — not a substitute for professional advice, and not certified by an heat pump engineer. Always have your specific appliance assessed by a qualified professional. Any heat pump work must be carried out by an MCS-certified heat pump engineer. If you notice a refrigerant leak, a burning smell or water leaking from the unit, switch it off at the isolator and call an MCS-certified heat pump engineer. Refrigerant work must be carried out by an F-Gas registered engineer.
Common causes
- Poor brine circuit circulation due to air in the ground loop Common
Air trapped in the brine/ground loop circuit reduces flow, causing the fluid temperature to drop sharply. This is one of the most frequent triggers for Alarm 60 and is resolved by a thorough bleed of the collector circuit.
- Low glycol fluid level or insufficient brine pressure Common
If the glycol level in the expansion or level vessel has dropped — typically from a small leak or gradual permeation — the ground loop pressure falls below the operating range (usually around 1 bar). Reduced fluid volume means less heat exchange capacity and colder outgoing temperatures.
- Blocked particle filter on the brine circuit Sometimes
Ground loop systems use a particle or strainer filter to protect the pump and heat exchanger. Over time this can accumulate debris, restricting flow enough to trigger the low-temperature alarm.
- Brine pump failure or reduced performance Sometimes
If the circulator pump on the ground loop side is running slowly, seized, or has failed entirely, brine flow drops and the outgoing fluid temperature falls below the alarm threshold.
- Refrigerant circuit fault Rare
In rarer cases, a fault within the sealed refrigerant circuit — such as a refrigerant leak or expansion valve issue — can cause abnormally low temperatures on the brine side. This requires an F-Gas registered engineer to investigate and repair.
How to fix it
- Check the ground loop pressure gauge DIY safe
Locate the pressure gauge on the brine/ground loop side of your Nibe unit. A healthy system typically reads around 1 bar. If the reading is noticeably lower, this points to a fluid loss and the circuit will need topping up by an engineer. Note the reading so you can report it accurately.
- Inspect the expansion or level vessel for visible glycol DIY safe
Look at the level vessel associated with the ground loop. If it appears empty or very low, glycol fluid has been lost. Do not attempt to top up the ground loop yourself — the correct glycol mix and concentration must be maintained by a qualified engineer to protect the system and preserve manufacturer warranty.
- Check for visible leaks around accessible brine pipework DIY safe
Walk around any accessible sections of internal brine pipework and pipe connections near the heat pump unit. Look for damp patches, staining, or signs of fluid. If you spot a leak, turn off the heat pump and call an engineer promptly — do not leave the system running with a known leak.
- Reset the alarm from the Nibe controller DIY safe
On your Nibe display, navigate to the active alarm message and select the option to view more information, then choose 'Reset alarm and try again'. The controller will restart and the heat pump will attempt normal operation. If Alarm 60 returns immediately or shortly afterwards, do not keep resetting — the underlying problem needs professional attention.
- Have an MCS-certified engineer bleed the brine circuit and inspect the pump and filter heat pump engineer
A qualified engineer should bleed the ground loop collector circuit to remove trapped air, check the glycol concentration and freezing point, inspect and clean the particle filter, and verify that the brine circulator pump is operating correctly. These tasks require specialist tools and knowledge of sealed hydronic circuits.
- If a refrigerant circuit fault is suspected, call an F-Gas registered engineer heat pump engineer
Should the above checks not resolve the fault, the problem may lie within the refrigerant circuit. Only an F-Gas registered engineer is legally permitted to work on the sealed refrigerant side. Nibe recommends using an Approved Repair Partner who is factory-trained on their ground source range.
Parts you may need
- Brine/ground loop circulator pump (up to 40 kW) · from £180
- Brine/ground loop circulator pump (40–60 kW) · from £245
- Ground loop particle/strainer filter cartridge · from £35
- Glycol heat transfer fluid (per litre, propylene glycol) · from £12
- Ground loop expansion vessel · from £95
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £150–£400, depending on the underlying cause.
Frequently asked questions
Can I reset Nibe Alarm 60 myself?
Yes, you can attempt a reset via the Nibe controller menu — find the alarm, select 'Reset alarm and try again', and the unit will restart. However, if the fault returns, resetting it repeatedly will not fix the underlying cause. You should arrange an engineer visit if the alarm comes back within a few hours or immediately on restart.
Is Nibe Alarm 60 dangerous?
The heat pump itself locks out the compressor when Alarm 60 triggers, so there is no immediate safety hazard in the way there might be with a pressure vessel or electrical fault. However, leaving the system unresolved means your home will lose heating and potentially hot water, and continued low glycol levels can damage the ground loop pump or heat exchanger if the unit restarts without adequate fluid.
Why is my ground loop pressure low and how do I top it up?
Ground loop pressure can drop over time if glycol fluid has been lost through a small leak or micro-permeation, or if the system was never correctly pressurised at installation. Topping up is not a straightforward DIY task — the glycol must be mixed to the correct concentration (typically 25–30% for UK ground temperatures) to prevent freezing and protect the pipework. An MCS-certified engineer will pressure-test the circuit, identify any leak, and refill using the correct fluid mix.
How much does it cost to fix Nibe Alarm 60 in the UK?
Most Alarm 60 repairs fall in the range of £150 to £400. A straightforward bleed, filter clean, and glycol top-up typically costs £150–£250 including the engineer callout. If the brine circulator pump needs replacing, expect to pay £300–£450 for parts and labour. In the rare situation where a refrigerant circuit fault is involved — such as a leak or compressor issue — costs can rise significantly beyond this range, sometimes to £800 or more. An annual service plan (typically £150–£250 per year) can help catch brine pressure issues before they trigger an alarm.