Commercial Air Conditioning Service, F-Gas Checks and TM44 Inspections

How this differs from whole-building PPM

Worth being clear about scope up front. Our planned preventative maintenance page covers a contract across all the plant in a building — boilers, ventilation, chillers, controls, the lot — scheduled against SFG20 task schedules. This page is narrower and deeper: it is about the air conditioning specifically, and about the two compliance duties that attach to AC and to nothing else in the plant room.

If you have a mixed building, you probably want the whole-building contract. If you have air conditioning and want to understand what the law actually requires of you, you are in the right place.

What an air conditioning service visit should cover

A service that consists of changing a filter and leaving is not a service. A competent visit covers the following, and produces a report with readings in it.

Airside. Filters inspected, cleaned or replaced — the single highest-impact item, because a loaded filter reduces airflow, drops efficiency and can ice the coil. Indoor and outdoor coils inspected and cleaned; condenser fouling is the most common preventable cause of poor performance and it is heavily site-dependent, with kitchen extract, tree pollen and urban dust all shortening the interval. Fan condition, bearing noise and vibration checked. Air-on and air-off temperatures measured across the coils so performance can be trended between visits.

Condensate. Drain trays cleaned, drain lines flushed and proved, traps checked, condensate pumps tested. Neglected condensate is one of the most common causes of both indoor water damage and microbial growth in the tray, and it takes minutes to check.

Refrigerant side. Operating pressures recorded, superheat and subcooling calculated, and the charge assessed against design. This is also where a slow leak gets caught before it becomes a failure.

Electrical and controls. Compressor current draw against nameplate, contactor and terminal condition, isolator checks, and a review of the controller's fault and event log. Setpoints, schedules and deadbands verified against how the building is actually occupied — a system heating and cooling against itself because someone set a 1°C deadband will quietly burn money forever.

Documentation. A written report with measured values, so you can see trends rather than a series of unrelated "all OK" visits.

F-Gas leak checking: intervals set by charge, not by calendar

The frequency of mandatory leak checking is not a fixed annual thing — it scales with how much refrigerant the system holds, expressed as tonnes of CO₂ equivalent (the physical charge in kilograms multiplied by the refrigerant's global warming potential). The thresholds sit at 5, 50 and 500 tonnes CO₂e, with checking required more frequently as you move up the bands, and installing automatic leak detection where required extends the intervals.

The consequence of the tCO₂e basis is one that catches people out: two systems holding the same weight of refrigerant can fall in different bands purely because of the gas they are charged with. Moving from a high-GWP refrigerant to a lower-GWP one can drop a system into a less onerous checking band for the same physical charge — a genuine ongoing saving that rarely appears in a replacement business case.

Alongside checking, you must keep records — quantities installed, added and recovered, check dates and results, repairs and verification re-checks, and who did the work. The work itself has to be done by a certified engineer working for a certified company. The duty is the operator's. Our F-Gas regulations guide goes into detail; confirm the current position on GOV.UK and via REFCOM.

TM44 air conditioning inspections: the duty most buildings miss

This is a genuinely separate legal requirement and it trips up buildings that consider themselves well-managed, because it sits under the Energy Performance of Buildings (England and Wales) Regulations 2012 rather than under F-Gas.

The rule: air conditioning systems with an effective rated output of more than 12 kW must be inspected by an accredited energy assessor, at intervals of no more than five years. The inspection is guided by CIBSE TM44.

The trap is the aggregation. The threshold applies to the system as a whole — and, in the government's own words, that includes systems made up of individual units each below 12 kW whose combined effective rated output exceeds it. A building with six 3 kW cassettes has an 18 kW system and a legal duty, even though no single unit comes close to the threshold.

What the report contains. The building address, the assessor's name, the inspection date, an assessment of the system's likely efficiency with suggestions for improvement, any faults identified, and an evaluation of maintenance, installed controls, system sizing relative to the cooling load, and opportunities to optimise performance. It must be lodged on the register and given a valid reference number before it is released to the building owner or manager.

Enforcement and penalties. Local Weights and Measures Authorities — in practice Trading Standards — enforce it. The fixed penalty for not having a report is currently £300, with a further £200 for failing to provide it to an enforcement officer within seven days of a request. Confirm current levels on GOV.UK.

Two practical points. First, the report is not just a compliance artefact — a decent TM44 assessment identifies oversizing, poor control strategies and improvement opportunities, and it is one of the cheaper pieces of energy analysis you can buy. Second, a TM44 inspection is carried out by an accredited energy assessor and is a distinct exercise from your maintenance contract; a service visit does not discharge the duty.

Service intervals: how often is enough

Twice a year is the common baseline for comfort cooling — typically a pre-summer visit that gets the cooling side right before it is needed, and an autumn visit covering heating changeover and the winter check. That baseline moves with the site.

Quarterly is more appropriate where the environment fouls plant quickly or where failure is expensive: commercial kitchens, where grease-laden air coats condenser coils; server and comms rooms, where the system runs continuously and downtime is costly; manufacturing with airborne dust; and coastal sites, where salt corrosion attacks coils and casings. Annual can be defensible on very lightly-used plant, but it is often false economy and it may not satisfy warranty conditions.

On warranties: manufacturer warranties on commercial plant are routinely conditional on documented planned maintenance at specified intervals. A warranty claim declined for want of a service history is an expensive lesson, and it is worth reading those conditions when the equipment is specified rather than when something fails.

What a maintenance contract should and should not include

Read the exclusions before the inclusions — that is where contracts differ. Points worth pinning down: whether consumables (filters, belts) are included or charged; whether refrigerant is included, and at what price, given that gas costs are rising with the phase-down; whether reactive callouts are included, capped or charged separately, and what the attendance window is; whether out-of-hours attendance carries a premium; whether F-Gas leak checking and record-keeping are inside the contract price; and — explicitly — whether TM44 is included, because it usually is not.

Indicative contract values run from a few hundred pounds a year for a handful of splits to five figures for a large mixed estate. The PPM page covers whole-building contracts priced against SFG20 task schedules.

Frequently asked questions

How often should commercial air conditioning be serviced?

Twice a year is the usual baseline for comfort cooling — a pre-summer visit and an autumn heating-changeover visit. Quarterly is more appropriate for commercial kitchens, server rooms, dusty industrial environments and coastal sites, where fouling or corrosion is faster or where failure is costly. Check your warranty conditions, which often specify a minimum interval.

What is a TM44 inspection and do I need one?

It is an air conditioning inspection required under the Energy Performance of Buildings Regulations. If the effective rated output of the air conditioning in your building exceeds 12 kW you must have one carried out by an accredited energy assessor at least every five years, with the report lodged on the register. Individual units under 12 kW aggregate toward the threshold, so several small cassettes can trigger the duty.

Does my maintenance contract cover TM44?

Usually not. TM44 must be carried out by an accredited energy assessor and is a separate exercise from routine servicing, so a maintenance visit does not discharge the duty. Check explicitly whether it is included and, if not, arrange it separately.

How often does F-Gas leak checking have to be done?

It depends on the refrigerant charge expressed in tonnes of CO2 equivalent, with thresholds at 5, 50 and 500 tonnes — larger charges require more frequent checks. Fitting automatic leak detection where required extends the intervals. Records of checks, repairs, verifications and refrigerant quantities must be kept, and the duty sits with the building operator.

Who is legally responsible, us or our contractor?

You are. Both the F-Gas record-keeping duty and the TM44 inspection duty sit with the building operator or owner. A contractor carries out the work and normally maintains the records on your behalf, but the legal responsibility — and any penalty — attaches to you.

We service commercial air conditioning and manage F-Gas compliance across the UK. For whole-building cover see maintenance and PPM and the SFG20 explainer. For faults see AC repair; for ageing plant see replacement. Background on the systems is on the commercial air conditioning overview, or request a quote.