Old Chiller Refrigerants: Identify Before Removal

Centrifugal chillers manufactured prior to 1995 were primarily designed around chlorofluorocarbon (CFC) refrigerants, most notably R-11 and R-12. R-11 was the standard for large-tonnage, low-pressure centrifugal machines due to its excellent thermodynamic properties and operating efficiency. Because R-11 operates at a negative pressure (a vacuum) under normal ambient conditions, these chillers require purge units to remove non-condensable gases and moisture that leak into the system. If you are evaluating a vintage centrifugal chiller with a purge unit, it is highly probable that it was originally charged with R-11, unless a retrofit was performed.

High-pressure R-12 was also utilized in certain centrifugal applications, though less commonly than R-11, as well as in some older reciprocating systems. The production of both R-11 and R-12 was halted in developed countries by 1996 under the Montreal Protocol due to their high ozone depletion potential (ODP). Consequently, any chiller still operating on these refrigerants relies entirely on reclaimed stockpiles. The scarcity of these legacy CFCs has driven up maintenance costs significantly, making the identification of these gases a primary driver for equipment replacement or decommissioning decisions.

For decades, R-22 (a hydrochlorofluorocarbon or HCFC) was the workhorse refrigerant for small to medium-tonnage industrial chillers utilizing reciprocating, scroll, and screw compressors. Its versatility and efficiency made it the default choice for air-cooled and water-cooled systems across countless manufacturing facilities and commercial plants. Chillers built between the 1970s and the late 2000s are very likely to contain R-22, provided they have not been retrofitted with drop-in replacements.

The phaseout of R-22 began later than the CFCs, with a complete ban on new production and import taking effect in the United States in 2020. While R-22 chillers can legally continue to operate, servicing them requires sourcing reclaimed refrigerant, which fluctuates in price and availability. Facility managers evaluating older R-22 equipment must weigh the cost of topping off a leaking system against the capital expense of upgrading to modern, HFC or HFO-based equipment. When decommissioning an R-22 chiller, the recovered refrigerant still holds value, but it must be handled by certified professionals to ensure compliance with environmental regulations.

As the industry moved away from CFCs in the 1990s, manufacturers introduced transitional refrigerants to bridge the gap. R-123, an HCFC, was developed as a direct replacement for R-11 in low-pressure centrifugal chillers. Many older R-11 chillers were retrofitted to use R-123, and new machines were designed specifically for it. While R-123 has a significantly lower ODP than R-11, it is still an HCFC and is subject to its own phaseout schedule, with new equipment production halted in 2020. Identifying an R-123 chiller often involves checking for a purge unit, similar to R-11 systems, but the data plate will confirm the specific charge.

Simultaneously, R-134a (an HFC) emerged as the primary zero-ODP replacement for R-12 and eventually became a standard for many centrifugal, screw, and scroll chillers. Chillers manufactured from the late 1990s through the 2010s frequently utilize R-134a. While R-134a does not deplete the ozone layer, it has a high global warming potential (GWP), which has led to its inclusion in more recent phasedown regulations like the AIM Act. Therefore, even chillers utilizing these "newer" transitional refrigerants are now facing regulatory pressures, making accurate identification essential for long-term facility planning.

Determining the exact refrigerant in an older chiller cannot rely solely on the equipment's age or compressor type. The most reliable method of identification is locating the manufacturer's data plate, typically riveted or adhered to the chiller's control panel or main structural frame. This plate lists the factory-designated refrigerant type and the total charge weight. However, because industrial chillers have lifespans exceeding 20 to 30 years, many have undergone significant modifications, including refrigerant retrofits, during their operational history.

If a chiller was retrofitted (for example, from R-11 to R-123, or from R-22 to an HFC blend like R-407C), the servicing contractor should have affixed a new label detailing the updated refrigerant type, the date of the conversion, and the type of lubricating oil used (such as POE or mineral oil). If the data plate is illegible or missing, or if there is conflicting labeling, a certified HVAC technician must extract a sample of the refrigerant and test it using a refrigerant analyzer. Guessing the refrigerant type can lead to catastrophic compressor failure if the wrong gas or oil is introduced, or severe legal penalties if handled improperly during decommissioning.