In short
An urgent commercial HVAC fault is one that stops ventilation, heating or cooling to occupied or critical spaces, causes leaks, or trips equipment repeatedly. Record alarms and fault codes, check the controls are calling for the plant without opening equipment, and contact a commercial HVAC engineer. Non-critical comfort issues can usually be scheduled as planned maintenance.
Is it urgent?
Call now if
- Ventilation has failed in an occupied building, kitchen or plant area
- Cooling has failed to a server room, comms room or other critical space
- An air handling unit has shut down and will not restart
- Water is leaking from HVAC equipment onto electrics or occupied areas
Usually suitable for scheduled work
- One room or zone is warmer or cooler than others
- A noisy fan coil or unit that is still working
- Filter alarms, servicing and general performance concerns
Heating, cooling and ventilation failures
Commercial HVAC systems keep occupied spaces ventilated, heated and cooled. A failure becomes urgent when it affects people’s safety, critical equipment or the building’s ability to operate.
Urgent failure or maintenance issue?
| Situation | Typical priority |
|---|---|
| Ventilation failed in occupied space or kitchen | Urgent: call |
| Server or comms room cooling failed | Urgent: call |
| Central AHU shut down, will not restart | Urgent: call |
| Water leaking onto electrics or stock | Urgent: call, isolate if safe |
| One fan coil not heating or cooling | Usually scheduled |
| Filter alarm, noisy fan still running | Usually scheduled |
HVAC shutdowns and air handling unit faults
Air handling units stop for safety reasons as well as failures: frost protection, fire alarm interlocks, airflow proving and motor overloads all shut plant down. Recording the alarm helps the engineer tell a safety shutdown from a failure.
Fan coil unit failures
Fan coils fail locally: stuck valves, failed fans, blocked condensate drains and controller faults. Leaks from blocked condensate drains or failed condensate pumps are the most common urgent fan coil problem.
Ventilation equipment problems
Extract and supply fans, belts and motors fail, and speed controllers or time schedules can stop systems running. Under the Workplace Regulations, enclosed workplaces need effective ventilation, so loss of ventilation in occupied areas needs prompt action.
Control system failures and alarms
Many HVAC “breakdowns” are control faults: a schedule not running, a lost BMS communication or a failed sensor. See emergency BMS and controls support.
Safe building management actions
- protect people first: move them from affected spaces if conditions are unsafe
- isolate leaking units only where it is safe and permitted
- protect electrics, stock and IT equipment from water
- record alarms, fault codes and the time of failure
- do not open panels, reset repeatedly or work on refrigerant pipework
Fault reporting and professional assessment
Give the engineer the site, equipment, symptoms, alarms and access details. They will diagnose the fault, make plant safe, repair where possible and recommend follow-up work. For a fuller breakdown checklist, see emergency preparation.
Gas-fired HVAC plant. If HVAC equipment is gas-fired and you smell gas, leave the area and call 0800 111 999.
For planned HVAC maintenance and non-urgent work, Flair also operates a dedicated commercial HVAC website, Commercial HVACS London.
Commercial HVAC Repairs: frequently asked questions
Can an HVAC failure affect an entire commercial building?
Yes. A failed central air handling unit, chiller, boiler, main pump or controller can affect every floor it serves. Faults in terminal units such as fan coils usually affect only individual rooms or zones.
What causes an air handling unit to shut down unexpectedly?
Common causes include fan motor or belt failure, frost protection trips, fire alarm interlocks, filter or airflow alarms, electrical faults, failed sensors and control or BMS faults. Note the alarm shown before calling.
Is a failed fan coil unit an emergency?
Usually not, unless it is leaking onto electrics or serves a critical space. Individual fan coil faults can normally be scheduled. Leaks should be isolated if it is safe to do so.
Should we reset HVAC equipment that has tripped?
A single reset may be acceptable where your site procedures allow it. If the equipment trips again, leave it off and call an engineer. Repeated resets can damage motors and compressors. Never reset after a fire alarm shutdown until the fire alarm has been cleared.
Do you work on refrigerant systems?
Work on refrigerant circuits must be carried out by F-gas certified engineers. Tell us the equipment type when you call so the right engineer can be arranged.
UK guidance and references
Primary and industry sources relevant to this subject. Always check the current edition and how it applies to your building.
- Ventilation in the workplace Health and Safety Executive
- Workplace temperatures Health and Safety Executive
- F gas in refrigeration and air conditioning GOV.UK