NIBE alarms: the log is worth more than the alarm on screen
NIBE controllers keep an alarm history alongside operating data. Learn why the log answers questions the current alarm cannot, and what to capture.
What this means
A NIBE controller stores more than the alarm currently displayed. It keeps a history of previous alarms with timestamps and, on many models, operating values recorded alongside them, and that history answers questions the current alarm cannot: whether this has happened before, how often, and under what conditions.
Equipment and model context
NIBE air source and ground source heat pumps with controllers that store an alarm log and operating history
- NIBE F2120
- NIBE S2125
- NIBE F1155
- NIBE SMO and VVM controllers
NIBE controllers differ between the F, S, SMO, and VVM families in what they log and how it is reached, and an alarm number is interpreted against the manual for that controller. A number from one family should not be applied to another even within the NIBE range.
What you may notice
- An alarm is displayed and heating or hot water becomes unavailable or reduced.
- The system had been alarming intermittently for weeks before anybody investigated.
- Performance has been declining across a season without any alarm until recently.
Likely causes
- Water flow below what the heat exchanger requires raises protective alarms on the heating side.
- Refrigerant-side conditions produce their own alarms and require certified attention.
- Sensing elements on either circuit can report values outside the range the controller accepts.
Diagnostic paths
This is not the first alarm
The alarm log shows earlier entries, possibly the same number, going back weeks or months before anybody acted.
Photograph the log rather than only the current screen. A repeating alarm with timestamps turns an isolated event into a pattern an installer can work from.
The log shows different alarms in sequence
Several distinct alarm numbers appear in the history rather than one repeating, sometimes within a short period.
Capture the sequence and the order. Alarms that follow one another often describe a chain, and the first one in the sequence is where the investigation starts.
The alarm cleared before anyone looked
Heating returned on its own and the current screen shows no alarm, leaving nothing to report by the time help was arranged.
Go to the alarm log. On a NIBE controller a cleared alarm is still recorded, which is precisely what makes intermittent faults diagnosable here.
An intermittent fault is defined by not being present when somebody looks. A stored history removes that problem entirely, because the record persists after the condition has passed and the heating has resumed.
- Condition occursThe alarm is raised and logged
- Condition passesHeating resumes on its own
- Screen clearsNothing visible to report
- Log persistsThe evidence survives the recovery
| Question | Current alarm | Alarm log |
|---|---|---|
| What is wrong now | Answers it | Also answers it |
| Has it happened before | Silent | Answers it with dates |
| How often | Silent | Answers it |
| What preceded it | Silent | Shows the sequence |
The most valuable thing a heat pump controller does
Heat pump faults are seasonal, gradual, and frequently intermittent, which is the worst combination for diagnosis. A circuit that is marginal alarms on the coldest morning of the month and then behaves for three weeks, by which time an installer arrives to find a system working perfectly and an owner describing something from memory.
A stored log changes that completely. It converts a recollection into timestamps, and timestamps can be matched against weather, against schedules, and against what the system was being asked for. That is the difference between a visit that measures something and a visit that observes nothing.
Photograph before anybody resets
The single instruction worth following on any NIBE alarm is to capture the log before the system is cleared, reset, or power cycled. Installers reset as a routine first step, and an owner who has photographed the history arrives at the conversation with evidence rather than an account.
Photograph the current alarm, then the log, then any operating values the controller shows alongside them. It takes a minute and it survives everything that happens afterwards. An installer handed timestamps and operating values can plan a visit around a hypothesis instead of starting from a description delivered from memory, and that changes what gets measured on the day. The heat pump operating temperatures guide covers what output to expect as conditions move, and the flow temperature and emitters page covers the water-side sizing question that sits behind a good share of these alarms.
What to give the technician
Send the installer photographs of the current alarm and the full log, the controller family and model, the operating values shown, and the outdoor conditions at each occurrence.
Safe homeowner checks
- Photograph the current alarm, then open the alarm log and photograph the history with its timestamps.
- Capture any operating values the controller displays alongside the log, including flow and return temperatures.
- Note the outdoor conditions and what the system was being asked for when the alarm occurred.
Is a reset appropriate?
Clearing an alarm lets the system continue and does not remove the entry from the log, which is why the log is the reliable record. Capture it first in case a reset is performed before you are asked.
When to call a technician
- Refrigerant-side alarms require a certified handler under F-Gas rules in the United Kingdom and European Union and under EPA Section 608 in the United States.
- Adjusting flow rates, pump settings, or controller parameters on a heat pump installation affects how the equipment operates across its whole envelope and belongs to the commissioning installer.
Questions people ask about this
Where is the alarm log on a NIBE heat pump?
It sits in the controller menus alongside operating information, and the exact path differs between the F, S, SMO, and VVM families. The manual for your controller gives the route.
The alarm cleared itself. Is there anything to report?
Yes. A cleared alarm remains in the log with its timestamp, which is what makes an intermittent fault diagnosable rather than a matter of recollection.
Do NIBE alarm numbers mean the same across models?
Not reliably. The controller families differ in what they monitor and how alarms are numbered, so an alarm is interpreted against the manual for the controller actually fitted.
Evidence recordHow this page was checked
operation manual, service manual · checked 2026-09-15
Every technical claim above was written from primary documentation held in the HVAC Bench evidence record: NIBE technical literature. Where a source limits a definition to certain models, test conditions, or product classes, that limit is repeated here rather than generalised.
- Documentation class
- operation manual, service manual
- Scope of the definition
- NIBE air source and ground source heat pumps with controllers that store an alarm log and operating history
- Last checked
- 2026-09-15