Chiller Conversions
R-134a Chiller Retrofit Eligibility
Before the truck rolls: is the refrigerant you have in mind listed for retrofit in a centrifugal chiller, does it fit an R-134a machine, and what does the OEM require? Eligibility first, from EPA's own listing table. The capacity figure comes after, with its operating condition beside it.
The Candidates, As EPA Lists Them (SNAP, last updated March 19, 2026)
| Refrigerant | SNAP | ASHRAE | Pressure class | For an R-134a machine |
|---|---|---|---|---|
| R-513A | R/N | A1 | positive-pressure (like R-134a) | Listed for retrofit, OEM procedure on file |
| R-450A | R/N | A1 | positive-pressure (like R-134a) | Listed for retrofit, OEM has final say |
| R-514A | R/N | B1 | low-pressure (purge machines) | Listed R/N, but a low-pressure fluid, B1 |
| R-1224yd(Z) | R/N | A1 | low-pressure (purge machines) | Listed R/N, but a low-pressure fluid |
| R-515B | N | A1 | positive-pressure (like R-134a) | New equipment only, not a retrofit |
| R-1234ze(E) | N | A2L | positive-pressure (like R-134a) | New equipment only, not a retrofit |
| R-1233zd(E) | N | A1 | low-pressure (purge machines) | New equipment only, not a retrofit |
| R-1336mzz(Z) | N | A1 | low-pressure (purge machines) | New equipment only, not a retrofit |
Capacity Relative to R-134a, With the Condition on Every Row
Two conditions, both stated. The first is Chemours' own Table 1 condition (104 F condensing, 14 F evaporating, 7 R liquid subcooling, 50 F return gas, 70 percent isentropic efficiency), at which the maker prints R-513A at 104 percent; it is a medium-temperature refrigeration point, and Chemours' guide scopes itself to refrigeration systems. The second is a water-chiller duty this site chose (100 F condensing (bubble point), 40 F evaporating (dew point), 5 R liquid subcooling, 45 F suction, 70 percent isentropic efficiency). Figures for N-listed refrigerants are what a new machine is sized for, not a retrofit result. Where no equation of state is available no figure is printed.
| Refrigerant | At Chemours' Table 1 condition | At water-chiller duty | Displacement to hold tonnage (chiller duty) | Figure means |
|---|---|---|---|---|
| R-513A | 103.8% | 101.5% | 0.986x | retrofit: an upper bound for the existing compressor on the new fluid, before the OEM re-rates |
| R-450A | 86.9% | 86.8% | 1.152x | retrofit: an upper bound for the existing compressor on the new fluid, before the OEM re-rates |
| R-514A | no figure | no figure | This site's cycle model (CoolProp 8.0.0) carries no equation of state for R-514A, and its maker publishes no comparison to R-134a: Chemours positions it against R-123. | |
| R-1224yd(Z) | no figure | no figure | This site's cycle model (CoolProp 8.0.0) carries no equation of state for R-1224yd(Z), and its maker publishes no comparison to R-134a: AGC positions it against HFC-245fa and HCFC-123. | |
| R-515B | 73.8% | 74.2% | 1.347x | new-machine sizing only; the listing does not permit the retrofit |
| R-1234ze(E) | 74.3% | 74.6% | 1.34x | new-machine sizing only; the listing does not permit the retrofit |
| R-1233zd(E) | 19.9% | 22% | 4.547x | new-machine sizing only; the listing does not permit the retrofit |
| R-1336mzz(Z) | 10.4% | 12.3% | 8.161x | new-machine sizing only; the listing does not permit the retrofit |
Why Eligibility Comes Before the Number
The question a technician asks is "what do I lose putting R-1234ze in this machine", and the honest answer is not a percentage. EPA's SNAP program lists each substitute for an end use with a Retrofit/New column, and for centrifugal chillers R-515B, R-1234ze(E), R-1233zd(E) and R-1336mzz(Z) carry an N: in the words of EPA's own listing notices, "(new equipment)". A capacity derate computed for one of them is a correct number attached to a job the listing does not permit. So this page reads the listing first and labels every figure for an N refrigerant as new-machine sizing.
The second sort is the one the SNAP table cannot make for you. R-514A boils at 84.4 F at one atmosphere on its maker's own property table ("Boiling Point at 1 atm 29.1 °C (84.4 °F)"), so at a 40 F chiller evaporator it sits in a vacuum: the class of machine that carries a purge unit and runs below atmosphere on the low side. The maker: "to replace R-123 in low pressure centrifugal chillers". SNAP's table is indexed by end use and substitute and carries no column for the refrigerant coming out, so its R/N cell says nothing about which machine in the end use the fluid fits; a listing that permits converting a low-pressure centrifugal to it is not a listing for this machine.
What survives is R-513A and R-450A. R-513A is listed R/N for centrifugal chillers, is A1 and positive-pressure like R-134a, and Johnson Controls / YORK has published the conversion for YK Chillers Mod H, G, F, E, D, C; YMC2 Chillers Mod A and B. It is a conversion with factory parts, not a can of gas. Johnson Controls / YORK's bulletin is quoted on the result, in its own words, because a technician needs to know before the truck rolls whether the machine qualifies, what parts to bring and what the machine will make afterward. The bulletin is silent on relief valves, vessel rating and the purge, and this page infers nothing from that silence.
Two corrections worth carrying. A figure in circulation puts R-1234ze at "50 percent lower capacity"; it traces to a Honeywell brochure sentence about the (Z) isomer against the (E) isomer. Honeywell's Solstice ze brochure says R-1234ze(Z) has a high boiling point and a volumetric capacity roughly 50 percent lower than R-1234ze(E); it prints no (E)-against-R-134a figure at all. Against R-134a, this site's model gives 74.6 percent at chiller duty, or 1.34x the displacement to hold tonnage, which is what a purpose-built R-1234ze machine is sized for (Honeywell Solstice ze Refrigerant (HFO-1234ze) brochure, BRO-22-40-EN (07/22)). And the three manufacturer documents on file disagree about the R-513A charge relative to R-134a; the disagreement is disclosed on the result rather than resolved by guessing.
Frequently Asked Questions
Can I retrofit my R-134a centrifugal chiller to R-1234ze or R-515B?
Not as a listed use. EPA's SNAP table for centrifugal chillers (last updated March 19, 2026) prints all four of R-515B, R-1234ze(E), R-1233zd(E) and R-1336mzz(Z) as N; the listing notice writes that category out as "(new equipment)". Putting one of them into an existing R-134a machine is not a listed use. The capacity table above prints R-1234ze(E) at 74.6 percent of R-134a at water-chiller duty and R-515B at 74.2 percent, about 1.34x the displacement to hold tonnage. Those are what a NEW machine is sized for, and are labelled that way; no tonnage is derived from them.
Which refrigerants can actually replace R-134a in an existing centrifugal chiller?
On the SNAP table, R-513A, R-450A, R-514A (B1) and R-1224yd(Z) carry R/N. EPA's table page defines no codes; its listing notice writes the N category out as "Centrifugal chillers (new equipment)" and describes retrofit acceptability in prose as acceptable "for new and retrofit equipment" (85 FR 79863 at 79865). SNAP's table is indexed by end use and substitute and has no column for the refrigerant coming out, so an R/N cell says nothing about which machine in the end use the fluid fits: R-514A (B1) and R-1224yd(Z) are low-pressure fluids their makers built for R-123 and R-245fa machines, and do not fit an R-134a machine. That leaves R-513A and R-450A. R-513A has a published OEM procedure. R-450A has none on file here; Honeywell publishes an R-450A retrofit guideline, but it converts R-12, R-401A and R-409A refrigeration systems, and its "not a drop-in" heading is about the mineral oil in those systems, not about an R-134a machine already on POE.
Is R-513A a drop-in for R-134a?
No. It is a conversion. Johnson Controls / YORK's SI0389 (226) for YK Chillers Mod H, G, F, E, D, C; YMC2 Chillers Mod A and B requires a factory re-rating before the change, a refrigerant-specific liquid level sensor by part number, a new control board (031-03630-001), a software floor (Y.OPT.01.03.308 or Y.OPT.01.00C.308 or greater) with the refrigerant selected, a label kit and a Section 608-certified technician; its companion SI0390 (919) does the same for YVAA and YVWA (screw chillers). The refrigerant circuit takes it (same POE, an azeotrope, 104 percent of R-134a capacity on Chemours' own Table 1, 103.8 on this site's model at the same condition); the controls do not. The bulletin's own hard negative: "Can R-22 YK units be converted? No. R-513A is not a viable conversion solution. The unit will not meet performance or capacity."
How much capacity do I lose going from R-134a to R-513A or R-450A?
R-513A loses none at the conditions on file: Chemours' Table 1 prints 104 percent of R-134a capacity at 104 F condensing and 14 F evaporating, and this site's cycle model gives 103.8 percent there and 101.5 percent at water-chiller duty (100 F condensing, 40 F evaporating). R-450A gives 86.8 percent at chiller duty, which is 1.152x the displacement to hold the same tonnage. A retrofit keeps the compressor, so the OEM's re-rating at your design conditions is the number to install to; these are cycle-model figures at stated conditions, not ratings.
Why does the tool refuse R-514A (B1) for an R-134a machine when SNAP lists it R/N?
R-514A is listed R/N for centrifugal chillers, and that listing is for the low-pressure machines it was made for. It is not an R-134a retrofit: the pressure class is wrong and it is a B1 fluid. Chemours made Opteon XP30 "to replace R-123 in low pressure centrifugal chillers", and it is ASHRAE B1, higher toxicity. Its SNAP listing permits converting a low-pressure R-123 machine to it; that is a different machine with a purge unit and a vacuum on the low side. The B1 class also raises the ASHRAE 15 machinery-room and detector questions for any machine it does go into, which this tool does not answer and refuses to compute.
Does the retrofit change my EPA leak repair obligations?
It can, because the leak repair rule turns on what is in the machine. R-513A and R-450A contain HFC-134a, so 40 CFR 84.106 reaches the converted machine at a full charge of 15 lb or more, exactly as it reached the R-134a one (the residential and light commercial AC and heat pump subsector is outside 84.106 entirely under 84.106(a)(3)(ii), and a centrifugal chiller is never in it); R-514A and R-1224yd(Z) contain no HFC and sit below the 53 GWP cutoff, so neither leak repair rule would reach them. The tool runs the shipped leak-rate engine at the new refrigerant and your subsector and prints its answer. And the charge added at the conversion is not a leak-rate addition: under 84.106(b) the leak rate is calculated on every addition unless it is made immediately following a retrofit.
Can I still buy a new R-134a centrifugal chiller, or keep running the one I have?
Keep running it, yes: SNAP still lists HFC-134a "R/N" for centrifugal chillers. Buy a new one for this end use, no: the listing status reads "Unacceptable in new equipment, except as otherwise allowed under a narrowed use limit for military marine vessels and human-rated spacecraft and related support equipment, as of January 1, 2024." Technology Transitions adds its own dates for a new machine on R-134a (GWP 1430): manufacture and import of stand-alone comfort-cooling chillers using a regulated substance at 700 or greater ended January 1, 2025 (40 CFR 84.54(a)(10)(i)), industrial process refrigeration chillers January 1, 2026 (40 CFR 84.54(a)(10)(iii)), and new data-center systems January 1, 2027 (40 CFR 84.54(c)(13)). 84.54(e) lists three actions that count as an installation, increasing the machine's cooling capacity among them (84.54(e)(2)); a refrigerant conversion is not among them.
Chemours, JCI and Honeywell disagree on the R-513A charge. Which is right?
Chemours (C-10302) and JCI (SI0389) print an initial charge of about 85 percent and a final charge of about 97 percent of the R-134a charge; Honeywell's chiller guide prints approximately 8 percent higher than R-134a. This tool publishes no charge figure of its own and shows all three. The OEM's re-rating and the sight glass decide it on the machine.
Related Calculators
EPA Refrigerant Leak Rate Calculator
The converted machine's additions, on the new refrigerant: coverage, the 10 percent comfort-cooling trigger and the repair clock under 40 CFR 84.106.
Refrigerant Blend Top-Off Check
After the conversion the machine holds a blend. Whether it can be topped off after a leak, from the maker's own glide and leak-recharge data.
Chiller Purge Pump-Out Leak Check
For the low-pressure machines R-514A actually goes into: purge minutes per day against Trane's Figure 2 by tonnage, for R-123 and R-514A CenTraVac.
Converted? Every addition after it has a leak rate.
The charge that goes in at the retrofit is exempt under 40 CFR 84.106(b). Every addition after it is calculated on the new refrigerant, and the leak-rate calculator opens on this machine.