How often should HVAC be maintained? What is required and what is chosen

What has a statutory interval

Air conditioning inspections, no more than 5 years apart

Gov.uk states that all air conditioning systems with an effective rated output of more than 12kW must be regularly inspected by an energy assessor, and that the inspections must be no more than five years apart. That is England and Wales, under the Energy Performance of Buildings Regulations (gov.uk).

F gas leak checks, 12, 6 or 3 months by charge

Frequency depends on the carbon dioxide equivalent of the refrigerant charge, not the size of the unit: at least every 12 months from 5 tonnes, every 6 months from 50 tonnes, every 3 months from 500 tonnes, with automatic leak detection doubling the permitted interval (gov.uk).

Inspection within 3 months on change of control

If control of a system passes to you and you were not given an inspection report, gov.uk requires the system to be inspected within three months of you taking over.

What does not

There is no statutory frequency for planned preventative maintenance of HVAC plant. Nobody is legally obliged to service an air handling unit quarterly. What the law does require, under the Provision and Use of Work Equipment Regulations 1998, is that work equipment is maintained in an efficient state, in efficient working order and in good repair, and HSE expects the need for inspection and its frequency to be determined through risk assessment (HSE). Frequency is therefore a judgement you make and should be able to justify, not a number you look up.

How to set a frequency you can defend

• Start from the manufacturer. Filter, belt, bearing and coil intervals are published for the equipment you own.
• Weight by criticality. A server room close control unit and a meeting room split are not on the same regime, even in the same building.
• Weight by environment. Coastal, dusty, kitchen extract and industrial installations foul faster than a clean office.
• Weight by consequence of failure. If a failure closes a trading floor, a kitchen or a ward, that is your argument for more frequent attention.
• Write the reasoning down once. That record is what turns your frequency from an arbitrary number into a defensible decision.

Water systems bring their own regime. If your HVAC includes cooling towers, evaporative condensers or significant hot and cold water services, legionella control has its own duties and its own monitoring frequencies that sit outside a standard HVAC PPM schedule.