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Chiller refrigerants after R134a: R1234ze, R513A and others

Updated 23 October 2026 · SEO Dons Editorial

Is R134a being banned in chillers?

No. GOV.UK's table of F gas bans in new air conditioning and heat pump systems lists larger systems, such as chillers, among the exceptions to the small single split ban. R134a has a GWP of 1,430 on the GOV.UK list, under the 2,500 line above which virgin gas cannot top up systems holding 40 tonnes of CO2 equivalent or more. The pressure on R134a is supply and cost, because the HFC phasedown caps what can be placed on the market. The air conditioning ban page sets out the full list of restrictions.

The leak-check weight is the practical difference. GOV.UK's table shows 3.5 kg of R134a reaches 5 tonnes of CO2 equivalent, where annual checks start, and 350 kg reaches 500 tonnes, where leak detection is required.

How do the main chiller refrigerants compare?

GWP figures use the Great Britain legal basis, with the source for each choice in the Sources list. The GWP table uses the same numbers.

RefrigerantGWPClassWhat the sources say
R134a1,430A1The existing standard for chillers and medium or high temperature refrigeration
R513A631A1Chemours: replacement for R-134a in chillers; suitable for new and retrofit use. Daikin offers it in its EWYS-4Z (400 to 800 kW)
R515B293A1Solstice: benefits "in new systems", efficiency equal to R-134a
R1234ze7A2LSolstice and A-Gas: alternative to R-134a in air-cooled and water-cooled chillers. Daikin offers it, with R-513A and R134a, in its 150 to 1,950 kW TZ-D range
R32675A2LDaikin air-cooled scroll chillers EWAT-B-C, 252 to 1,012 kW
R454B466A2LChemours: selected by Mitsubishi Electric Hydronics for chillers and heat pumps
R290 (propane)3A3Daikin Applied UK range 17 to 2,000 kW; Rinnai UK range 40 to 410 kW

Three further points sit outside the table:

  • R1233zd. Solstice describes it as a non-flammable, ultra-low GWP replacement for R-123 in low pressure centrifugal chillers, so it answers a different question from R134a replacement.
  • Ammonia and CO2. The GB annex lists ammonia at a GWP of 0, and A-Gas calls CO2 (R744) a natural refrigerant with a GWP of 1. The Institute of Refrigeration publishes separate safety codes for both, which signals specialist plant.
  • Different published numbers. The GB annex lists R-1234ze at 7, while Solstice shows less than 1. Ask which basis a quote uses.

How does the refrigerant change the leak-check band?

The band follows the charge multiplied by the GWP, in tonnes of CO2 equivalent. GOV.UK sets a check at least every 12 months from 5 to under 50 tonnes and at least every 6 months from 50 to under 500 tonnes. The table below is a hypothetical comparison that assumes the same charge in every case, which real machines will not share, so treat it as a sense of scale rather than a design figure.

Refrigerant40 kg chargeCheck interval200 kg chargeCheck interval
R134a (1,430)57.2 t6 months286.0 t6 months
R32 (675)27.0 t12 months135.0 t6 months
R513A (631)25.2 t12 months126.2 t6 months
R454B (466)18.6 t12 months93.2 t6 months
R515B (293)11.7 t12 months58.6 t6 months

A lower GWP can move a small chiller into a lighter band, but at larger charges every option here stays in the six-monthly band. Propane is not an F gas, and R1234ze sits in GOV.UK's group of gases that must be reported on only, so ask a certified contractor how the duty applies to those.

What does the safety class change in the plant room?

With A1 gases the design question is mainly pressure and toxicity. With A2L and A3 it also includes flammability. BSI says BS EN 378-3 covers the installation site, including plant space, and that the 2020 revision clarified separate refrigeration machinery rooms and considered 2L refrigerants. CIBSE Journal adds that the UK's DSEAR regime applies to refrigerants, with risk assessment and safeguards such as leak detection, ventilation, shut-off valves and alarms expected. It also says systems with A2L and A3 refrigerants are more likely to be Category 2 or above for pressure equipment, which needs Approved Body assessment.

CIBSE Journal separates two ways of making a system safe. Intrinsic safety limits the quantity of refrigerant so that a leak into the space cannot create an unsafe condition. Extrinsic safety uses other measures, such as the physical arrangement, additional safety equipment and operating procedures. Plant rooms and outdoor siting are the usual extrinsic tools for chillers.

REFCOM notes that A2L gases remain rated flammable under DSEAR. For propane, Daikin Applied UK describes a safety package of continuous leak detection, ATEX-certified switchbox ventilation, visual and acoustic alarms and an independent 230V supply. Air-cooled chillers keep the charge outdoors, which is a reason A2L and A3 machines are common in this sector. The types of chillers page explains the machine families.

What does a retrofit involve compared with a new chiller?

  1. Manufacturer approval. Chemours says its R-513A is an OEM-approved retrofit solution for existing equipment, and A-Gas says it can be used as a retrofit or in new installations. Solstice presents R-515B as a benefit "in new systems". Ask the chiller maker whether the exact model is approved for the new gas.
  2. Oil. A-Gas says compressors on R513A must be charged with polyolester oil, and those on R1234ze with modified polyolester oil.
  3. A change of class. REFCOM says lower flammability refrigerants should never be retrofitted into a standard HFC system without a full safety risk assessment, and that an installation passing EN 378 for one gas will very possibly not meet it for another.
  4. Recovery and records. A certified company recovers the old charge, and GOV.UK expects records of gas added and of recovery and disposal for systems of 5 tonnes CO2 equivalent or more.
  5. Performance. Chemours claims excellent capacity and energy efficiency against R-134a, and Solstice claims equal efficiency for R-515B. These are supplier claims, so ask for selection data at the design conditions.

A new commercial chiller avoids most of these steps because the refrigerant, oil, pressure design and plant-room measures are chosen together. The chiller cost guide covers what drives the price.

How should the options be compared on a quote?

Ask each bid to state the refrigerant and class, the GWP basis, the charge in kilograms, the CO2 equivalent and leak-check band, the plant-room measures, the manufacturer's approval for any retrofit, and the engineers' flammable-refrigerant training. Date the quote as well, because the supply of HFCs is capped and conditions can change. Readers who want quotes can send an enquiry through the site's form, and the chillers page shows the wider route.

Sources

Common questions

Can an R134a chiller keep running?

Yes. The sources reviewed set no removal date for working chillers, and GOV.UK's bans table treats chillers as an exception. Leak checks, certified servicing and records still apply.

Is R1234ze really non-flammable?

It depends on the scheme. A-Gas says it is non-flammable under ADR but classified A2L under ASHRAE, and Solstice lists it as A2L (mildly flammable). Plant-room design follows the A2L class.

Which chiller gas has the lowest GWP?

On the GB legal basis ammonia is 0, propane 3 and R1234ze 7, against 293 for R515B and 631 for R513A. Manufacturer pages may show different figures, so compare on one basis.

Does changing refrigerant change the leak-check band?

It can, because the band follows charge multiplied by GWP. For R134a 3.5 kg reaches 5 tonnes. A gas with a lower GWP needs a larger charge to reach it, but the gas, charge and mixture must be checked with a certified contractor.

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