PSSR for Refrigeration and Air Conditioning Plant

PSSR, the Pressure Systems Safety Regulations 2000, catches refrigeration and air conditioning plant once total installed compressor power passes 25 kW. Above that line you need a written scheme of examination, drawn up or certified by a competent person, and periodic statutory examinations. Below it, the plant is excepted from every regulation.

A common moment in this job. Your insurer's surveyor walks the plant room, looks up at the condensing rack, and asks to see the written scheme of examination. You have F-Gas certificates, service sheets going back years and a paid maintenance contract. Nobody has heard of the document being asked for. That gap is what this post closes.

At a glance

Question	Answer
What PSSR is	The Pressure Systems Safety Regulations 2000 (SI 2000/128), in force since 21 February 2000
Does it cover refrigeration and AC?	Yes; HSE lists "heat exchangers and refrigeration plant" as examples of pressure systems
The refrigeration threshold	Vapour compression systems with total installed compressor power "not exceeding 25 kW" are excepted (Schedule 1). Above 25 kW, PSSR applies
Who holds the duty	The user of an installed system, or the owner of a mobile system
The core document	A written scheme of examination, certified by a competent person before operation (regulation 8)
After that	Periodic examination to the scheme (regulation 9), with reports and records kept (regulation 14)
New equipment	Placing new pressure equipment on the market is a separate regime: the Pressure Equipment (Safety) Regulations 2016

Source: The Pressure Systems Safety Regulations 2000 and Pressure Systems Safety Regulations 2000 (PSSR), HSE

What counts as a pressure system and a relevant fluid

PSSR only applies where the system contains a "relevant fluid". HSE's definition: "steam at any pressure", "compressed or liquefied gas, including air, at a pressure greater than 0.5 bar above atmospheric pressure", "pressurised hot water above 110 °C", and "a gas dissolved under pressure in a solvent (acetylene)". Hydraulic oil is excluded because it does not store energy in the system.

Read that second line again. A refrigerant is a liquefied gas under pressure, sitting well above 0.5 bar whenever the plant runs, so the circuit in a cold room pack, a chiller or a VRF condenser is exactly what these regulations were written for. HSE's leaflet INDG261, Pressure systems: a brief guide to safety, says so, listing "heat exchangers and refrigeration plant" among its examples. The definition also takes in the connected pipework and protective devices: on refrigeration plant, the receiver, condenser, discharge and liquid lines, relief valves and high-pressure cut-outs.

The 25 kW rule for refrigeration and air conditioning

Refrigeration has its own line in the regulations, and it is about installed power, not refrigerant or charge. Schedule 1, paragraph 18 excepts "any vapour compression refrigeration system incorporating compressor drive motors, including standby compressor motors, having a total installed power not exceeding 25 kW" (PSSR 2000, Schedule 1).

Three things fall out of that. It is the total of every compressor drive motor, standby machines included. Comfort cooling runs on the same cycle, so a large chiller or VRF installation can be in scope just as a cold room pack can. The threshold ignores the gas entirely: an HFC pack and a CO2 pack are treated the same, though CO2 pressures make the examination more consequential, as our post on what replaces HFCs covers.

A single undercounter cabinet will never come near 25 kW. A supermarket pack, cold store or multi-compressor chiller can. If you have never added up the motor plate ratings on your plant, that is job one.

Who holds the duty: user, owner and the leased plant trap

The "user" is whoever "has control of the operation of the pressure system"; the "owner" is the employer or self-employed person who owns it. HSE's split: the duty holder is "the user of an installed system, that is, one that is not a mobile system", or "the owner of a mobile system, that is, one that can be easily moved" (HSE, PSSR). Refrigeration plant is installed. If you control its operation, the duty is yours.

Leasing moves things around, and Schedule 2 exists for hire and lease arrangements. A supplier may "assume responsibility in writing for the WSE, the operation, the maintenance and the record keeping", and the user should still "make sure that the WSE is in place and that the certificate of examination is also current". If your plant sits in a landlord's demise or on a rental agreement, get the allocation in writing.

The written scheme of examination

Regulation 8 is the hinge. The user of an installed system and the owner of a mobile system shall not operate the system, or allow it to be operated, unless a written scheme for its periodic examination is in place. The scheme must be "drawn up, or certified as being suitable, by a competent person" and must "specify the nature and frequency of examination" (PSSR 2000, regulation 8).

It has to cover every protective device plus every vessel and pipe whose failure could give rise to danger, and where appropriate it must provide for examination before first use. INDG261 compares it to "an MOT for your car", then warns that "it is not a substitute for regular and routine maintenance". Both halves of that sentence matter.

The competent person is "a competent individual person (other than an employee) or a competent body of persons" (regulation 2). Where an organisation uses its own in-house competent person, HSE says they "should be independent from the operating functions of the organisation" and "must have sufficient authority to stop the use of the pressure equipment". The second test is the one that bites: whoever examines the plant has to be able to switch it off.

Examination, and what happens between examinations

Regulation 9 requires examination to the scheme, with a written report from the competent person after each one. The regulations set no fixed interval for refrigeration plant; the competent person sets the frequency in the scheme. Regulation 14 then requires you to keep "the last report relating to the system made by the competent person pursuant to regulation 9(3)", plus earlier reports and the manufacturer's information for the parts covered.

If the examiner finds something that cannot wait, regulation 10 takes over. The competent person must "forthwith make a written report" of the work needed and, within 14 days of completing the examination, send the same particulars to the enforcing authority. The user must ensure the system "is not operated" until the work is done. That is the part of PSSR that stops plant, and it is meant to.

Between examinations, the scheme assumes you are maintaining the plant. INDG261 is blunt: "there should be a maintenance programme for the system as a whole", and protective devices must be kept in good working order. An examination that finds a fouled condenser, a weeping joint and a relief valve nobody has touched in five years is a report on your maintenance as much as on the metal. Our post on what a refrigeration maintenance contract covers sets out what that routine work looks like.

PSSR duties by regulation number

The regulations split between the supply side and the people running the plant. Regulations 4 to 6 bind those who design, manufacture, supply and install pressure systems in the course of trade; regulations 7 to 15 bind the user of an installed system or the owner of a mobile one.

Regulation	Duty	Who holds it
4	Design and construction	Designer, manufacturer, importer, supplier
5	Provision of information and marking	Person supplying the system
6	Installation	Installer and the employer controlling it
7	Safe operating limits	User or owner
8	Written scheme of examination	User or owner; scheme drawn up or certified by a competent person
9	Examination in accordance with the written scheme	User or owner to ensure; competent person to examine and report
10	Action in case of imminent danger	Competent person reports; user or owner stops operation
11	Operation	User or owner
12	Maintenance	User or owner
13	Modification and repair	User or owner
14	Keeping of records	User or owner
15	Precautions to prevent pressurisation of certain vessels	User or owner

Source: The Pressure Systems Safety Regulations 2000, contents; the exact wording sits in each regulation, and the Approved Code of Practice L122, Safety of pressure systems is the guidance that accompanies them

PSSR is law, not guidance. INDG261 notes that "health and safety inspectors seek to secure compliance with the law", and the regulations include a defence provision at regulation 16, which only exists because breach is an offence.

PSSR vs F-Gas vs the Pressure Equipment (Safety) Regulations 2016

Three regimes land on the same plant, and they are constantly confused. PSSR keeps in-service plant safe. F-Gas controls what leaks out of it. The Pressure Equipment (Safety) Regulations 2016 govern equipment only until it is first made available on the market: their explanatory note says they implement the directive "relating to the making available on the market of pressure equipment", with manufacturers required to "carry out the relevant conformity assessment procedure" before affixing the marking.

	PSSR 2000	F-Gas rules	PER 2016
What it protects against	Stored energy: the physical failure of a pressure system	Emissions of fluorinated greenhouse gases	Unsafe equipment reaching the market
Trigger for refrigeration plant	Vapour compression system over 25 kW total installed compressor power	Equipment containing HFCs, PFCs or SF6, with leak checks from 5 tonnes CO2 equivalent	New pressure equipment being made available on the market
Who it binds on your site	User of an installed system, owner of a mobile system	The operator of the equipment	Manufacturers, importers and distributors
Recurring obligation	Periodic examination to the written scheme	Leak checks: annually from "5 to less than 50" tonnes CO2e, six-monthly from "50 to less than 500"; hermetically sealed systems exempt below 10 tonnes	None once sold; duties end at the point of supply
The paper you hold	Written scheme and the competent person's reports	Leak check and refrigerant records	Declaration of conformity and the conformity marking

Source: Checking F gas equipment for leaks, GOV.UK and The Pressure Equipment (Safety) Regulations 2016

One plant, three regimes: making the visits line up

Here is where estates lose time. The F-Gas engineer comes for the leak check, the maintenance contractor comes for the PPM, the insurance examiner comes for the written scheme. Three visits, three reports, and nobody comparing notes. Yet the leak repair history the F-Gas contractor writes is exactly the evidence a PSSR examiner wants when assessing pipework, and the relief valve on the service sheet is the same protective device the scheme lists.

The written scheme is the spine. Build one plant register per site: installed compressor power, refrigerant and charge, safe operating limits, protective devices, scheme dates, leak check dates. Then sequence F-Gas checks and PPM so the plant is in good order before each statutory examination, and file the reports together. The multi-site version of this is in our post on F-Gas compliance across a multi-site estate.

One qualification. The examination is a separate statutory job with its own report, done by someone with the authority to stop the plant. Line the visits up; do not merge the roles.

When to get help

If the motor plates add up to more than 25 kW and there is no written scheme, you are operating outside the regulations and the fix starts with a competent person, not a service visit. Below the threshold, the exemption removes the paperwork but not the need to run plant safely and prove it. If you want that handled properly across London or the South East, our planned refrigeration servicing covers the routine maintenance an examiner expects to see recorded: family-run since 2004, F-Gas certified engineers.

Frequently asked questions

Does PSSR apply to air conditioning?

Yes, if the plant is big enough. Comfort cooling is vapour compression, so the same Schedule 1 threshold applies: excepted at or below 25 kW, in scope above it. Small room splits almost never reach the line; large chillers and VRF installations can.

What is a written scheme of examination?

The document regulation 8 requires before a qualifying pressure system is operated. It identifies the parts to be examined, including every protective device, and specifies the nature and frequency of examination, and it must be drawn up or certified as suitable by a competent person.

How often does refrigeration plant need a PSSR examination?

The regulations set no fixed interval. The competent person sets the frequency in the written scheme based on the system, its condition and its duty. If the scheme's date has passed, operating the plant is a breach whatever your own calendar says.

Who can act as the competent person?

Regulation 2 defines them as "a competent individual person (other than an employee) or a competent body of persons", and where an organisation uses its own in-house competent person, HSE says they should be independent from its operating functions and have the authority to stop the equipment being used.

Do small commercial fridges need a written scheme?

No. A plug-in display cabinet or bottle cooler runs from an ordinary socket, which cannot supply anything close to 25 kW, so it falls inside the Schedule 1 exception from all of the regulations. F-Gas rules still apply if it contains an HFC, but no written scheme is required.

Is a PSSR examination the same as a service?

No. A service is maintenance: cleaning, adjustment, refrigerant checks. A PSSR examination is a statutory, independent check by a competent person that the pressure system remains safe. As INDG261 puts it, the examination "is not a substitute for regular and routine maintenance".

The paperwork is the plant's memory

The plant itself rarely surprises anyone; racks fail the way racks fail. What surprises people is discovering that a system they have owned for a decade has been running outside a regime they never knew applied to it. The 25 kW line is quick to check against the motor plates, and the written scheme exists so the state of the plant is written down by a competent person.

Sort the register first: plant, power, refrigerant, scheme status. Everything else hangs off that list. If you want a hand with the maintenance side, ask us for a quote and we will start with what you actually have.

About the author: Ali Elm runs Be Cool Refrigeration & Air Conditioning, a family-run London firm that has been installing, servicing and repairing commercial refrigeration and air conditioning since 2004. His F-Gas certified team has delivered more than 2,000 projects across London and the South East.

Last updated: 9 October 2026