Air Conditioning Replacement: what forces it, and how to do it once

Why commercial air conditioning actually gets replaced

Ask most facilities managers why a system was replaced and the answer is "it failed". Look at the estate-wide pattern and a different story emerges: the overwhelming driver is refrigerant. Mechanical components on commercial AC are repairable, and plant regularly runs 15–20 years. What ends a system's life is usually the moment it can no longer be legally or economically recharged.

That is a useful thing to know, because refrigerant obsolescence is predictable. Unlike a compressor failure, you can see it coming years out and plan around it — which is the difference between a tendered, phased project and an emergency purchase.

R22: already terminal

R22 is an HCFC and has been comprehensively phased out. Since 2015 it has been banned for use in servicing existing equipment, and that ban covers recycled and reclaimed gas as well as virgin — a point that still surprises owners who assume a stockpile exists somewhere.

The practical effect: an R22 system can keep running indefinitely as long as it is sealed and healthy, and you can carry out repairs that do not involve adding refrigerant. But the moment it loses charge, it is finished. There is no compliant way to put the gas back.

If you still have R22 plant — and there is more of it in UK buildings than people expect, often in comms rooms and back-of-house areas nobody looks at — you are running an asset with no failure tolerance at all. That is a risk position worth converting into a budget line.

R410A: not banned, but the economics are moving

R410A (GWP 2,088) is the refrigerant in most systems installed over the last twenty years. It is not banned, and there is no cliff-edge date at which existing R410A plant becomes illegal.

What is happening instead is a quota-based phase-down: the GB F-Gas regime steadily reduces the total tonnage of CO₂-equivalent HFC that can be placed on the market. High-GWP gases consume quota disproportionately — a kilogram of R410A eats twenty times the quota of a kilogram of R32 measured in CO₂e — so suppliers preferentially allocate away from them, and prices rise well ahead of any ban.

The consequence for an owner is gradual rather than sudden. Recharging gets more expensive each year, so the arithmetic of "repair the leak and top it up" tips toward replacement earlier than it used to. Meanwhile, new equipment has largely moved to R32 (675) and R454B (around 466), with R290 (propane, GWP 3) on smaller duties. New single-split systems under 3 kg have been restricted to refrigerants below GWP 750 in GB since 1 January 2025. Regulatory detail changes — confirm the current position on GOV.UK.

The catch nobody mentions: A2L charge limits

Here is the part that turns a procurement exercise into a design exercise. R32 and R454B are classified A2L — mildly flammable. BS EN 378 therefore sets a maximum refrigerant charge in relation to the volume of the smallest occupied room the system serves.

The implication is significant: a like-for-like replacement is not always permissible. An old R410A system serving several small rooms — individual offices, hotel bedrooms, treatment rooms, small meeting rooms — may not be replaceable with an equivalent-duty A2L system on the same architecture, because the charge required would exceed what the smallest room volume allows.

The ways round it are genuine engineering choices, each with cost implications: split the system into more, smaller circuits; relocate or reconfigure indoor units; add mechanical ventilation or refrigerant leak detection with interlocks to permit a higher charge; or change system type entirely — a chilled-water system keeps refrigerant confined to the plant room and sidesteps the issue, which is one reason it becomes attractive in buildings with many small rooms.

If a replacement quote for a multi-room building arrives with no mention of charge limits, that is worth a question. It is the most common technical omission in AC replacement proposals.

Can the existing pipework be reused?

Sometimes, and it is worth establishing early because it materially changes both cost and disruption — re-piping an occupied building is often the largest single line in a replacement project.

What has to be checked: pipe sizing, because the new system's duty and refrigerant may require different diameters; pressure rating, since R410A and R32 run at markedly higher pressures than R22-era systems and older pipework may not be rated for it; condition, via pressure testing to prove integrity; and oil compatibility, which is the one that bites.

On that last point: R22 systems used mineral oil, while modern HFC systems use POE (polyol ester) oil. The two are not compatible, and residual mineral oil left in a pipework system will not return properly to the new compressor — the failure mode is oil starvation and a compressor that dies early, months after everyone has signed off the job. Where pipework is reused after an R22 system, it must be chemically flushed and verified, or the run replaced. A contractor proposing pipework reuse from an R22 system without flushing is proposing a future compressor failure.

Doing it while the building keeps working

Very few commercial buildings can close for a fortnight, so replacement is normally phased. The usual approaches: zone by zone, taking one floor or wing at a time so the rest of the building keeps cooling; seasonally, doing cooling-critical areas outside summer and heating-critical areas outside winter; and out of hours for the noisy and disruptive stages, particularly craneage and core drilling.

Temporary cooling is worth pricing in for critical spaces rather than improvising later. Portable units for a comms room during changeover cost far less than the outage they prevent.

Two logistical items dominate the programme in practice: craneage for rooftop plant, which may need a road closure and a permit and therefore weeks of notice; and refrigerant recovery from the old system, which is a legal requirement — the old charge must be recovered by a certified engineer and sent for reclamation or destruction, with records kept. It cannot simply be vented.

The efficiency gain, and how to value it honestly

Replacing a fifteen-year-old fixed-speed system with a modern inverter one typically produces a real reduction in energy use. The gain comes mostly from part-load behaviour: the old system could only cycle on and off, while an inverter modulates and runs continuously at reduced output, which is where a commercial system spends most of its life. Better heat exchangers, better fans and much better controls add to it.

Be careful with headline percentages, though. The honest way to size the benefit is against your measured consumption and your tariff, using the SEER and SCOP figures for the specific equipment under BS EN 14825 — not a generic manufacturer claim. Where a building has no sub-metering on the AC, a commercial energy audit is the sensible first step, because you cannot verify a saving you never measured a baseline for.

Two further benefits are often left out of the business case and shouldn't be. Moving to a lower-GWP refrigerant can drop the system into a less frequent F-Gas leak-checking band for the same physical charge, which is an ongoing cost reduction. And efficient cooling contributes to the building's EPC, which matters for MEES — currently EPC E to continue letting commercial space, with a proposed EPC B by 2031 for privately rented non-domestic buildings over 1,000 m², subject to secondary legislation. Our MEES and EPC guide covers where that stands.

What replacement costs, and how it is funded

Replacement generally costs less than a first-time installation into a building with no AC, because containment routes, electrical provision and structural support often already exist. It costs more than the equipment list suggests, because of strip-out, refrigerant recovery, making good, phasing and any A2L-driven redesign.

Indicative figures track the AC cost guide, with a strip-out and recovery allowance on top. Where a redesign is forced by charge limits, treat it as a new installation for budgeting purposes.

On funding: this is capital plant expenditure and the routes are the ordinary capital-allowance ones set out on our grants and funding page. HVAC plant is main-rate plant and machinery; solar PV, by contrast, sits in the special-rate pool and takes the Annual Investment Allowance route, which is why general advice about full expensing does not transfer cleanly between the two. There is no commercial equivalent of the domestic Boiler Upgrade Scheme. Confirm treatment with your accountant and against current GOV.UK guidance.

Frequently asked questions

Do I have to replace my R22 air conditioning?

Not while it is sealed and working — you can keep running it and carry out repairs that do not involve adding refrigerant. But R22 has been banned for servicing use since 2015, including recycled gas, so any significant refrigerant loss ends the system. In practice that means running R22 plant with no tolerance for failure, which is why most owners plan a replacement rather than wait.

Is R410A being banned?

No, there is no ban on existing R410A systems. What is happening is a quota-based phase-down of HFCs by CO2-equivalent tonnage, which makes high-GWP gases like R410A progressively scarcer and more expensive to buy. The effect is economic rather than legal: recharging costs rise, so replacement becomes the better value option earlier than it once did.

Can I reuse my existing refrigerant pipework?

Sometimes, but it must be checked for sizing, pressure rating and condition first. The critical issue when replacing an R22 system is oil: R22 used mineral oil and modern systems use POE, which are incompatible. Residual mineral oil causes oil starvation and early compressor failure, so the pipework must be chemically flushed and verified or replaced.

Why can't I just fit the same size system as before?

Because R32 and R454B are mildly flammable A2L refrigerants, and BS EN 378 limits refrigerant charge relative to the volume of the smallest room served. A system serving several small rooms may not legally take the charge an equivalent-duty replacement would need, so it may have to be split into more circuits, reconfigured, fitted with leak detection, or changed to a chilled-water design.

How disruptive is replacing air conditioning in an occupied building?

Manageable with phasing. Work is normally taken zone by zone so the rest of the building keeps running, noisy stages such as craneage and core drilling are moved out of hours, and temporary cooling is provided for critical spaces during changeover. Craneage for rooftop plant often needs weeks of notice for permits or a road closure.

We plan and deliver commercial air conditioning replacement across the UK, including R22 and R410A upgrades. See the commercial air conditioning overview for system choice, installation for how the work runs, repair for the repair-versus-replace decision, and funding for the capital-allowance routes. Or request a quote.