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We compiled some frequently asked questions on using CO2 refrigeration systems (with a particular look at how they compare to ammonia systems)


CO2, or R-744, is a natural, non-toxic, and non-flammable refrigerant with no net greenhouse gas effect. It provides the optimum balance of performance, efficiency and safety, ideal for both new installations and retrofits of existing systems. As a natural substance with minimal impact on the environment, it’s unlikely to be phased out (which can be quite a costly endeavor). It is non-corrosive with most materials, and a good option for R-22 (Freon) replacements.
We never tire of recommending CO2 as a consideration for your next refrigeration system. However, we realize that there are many questions concerning this refrigerant that go unanswered. While we strongly recommend contacting us directly for any specific queries, we thought we would compile a series of questions we have recently received about CO2. Hope this helps clear up some of the common doubts!CO2 Vs. Ammonia

  • How is the day-to-day operation of a CO2 system similar to or different from an ammonia system?  (For example: draining/adding oil, condenser/cooling tower maintenance and sanitization, etc.)

    The outdoor condenser is in fact a gas cooler. In transcritical mode the gas is no longuer condesing but ccooling down from high temperature to lower temperature. Since it could be done with a dry or adiabatic gas cooler, the usage of water is no longer required or slight amount for extreme warm outdoor conditions. This eliminate the water treatment system of a cooling tower and tremendously reduce water waist and usage.

  • How does the life span of a CO2 system compare to an ammonia system?

    The life span is very similar. All components are replaceable without requiring major renovation. Compressors are low-cost unitary equipment (vs overhauls), and multiple glycol chillers can be replace. All of the piping is stainless steel, so no rust and insulation would be armaflex covered with PVC.

  • How often will CO2 need to be charged to the system? What would this cost (compared to ammonia)?

    CO2 would never need to be charged to the system unless service requires emptying the charge for a major reparation (which is an unlikely scenario). In case of a leak, the charge for a 160 TR system would be around 500 lbs. The price of CO2 is between $2-$3 per pound.

  • In an indirect C02 system, is the glycol/brine system the same as would be used for an indirect ammonia system (header trench, under ice piping, etc.)?

    In other words, if we were to install a CO2/glycol indirect system today, and decide in the future to replace the system with an ammonia/glycol indirect system, can the underfloor glycol piping remain as is? Could we just disconnect the CO2 system and swap it out with an ammonia system?Absolutely. The glycol circuits would not be affected and will have no impact. In fact, the cooling tower supplied as the condenser in an R6 plant could remain and be used with an ammonia package replacement. 

  • Since CO2 is not self-alarming, what extra safety measures are needed?

    Please refer to the R744 Safety Data Sheet:


CO2 sds



  • What are the warranty package options for CO2 and ammonia refrigeration systems with heat recovery?

       All CIMCO systems have a 1-year warranty from start-up material, parts and labor.

  • Other than onsite training by the installer, what certificates or training courses are available on C02 refrigeration systems in Ontario?

Emerson does CO2 Training in Brantford on the entire system. CIMCO provides system training for customers after the installation is complete. We would go over the day-to-day maintenance requirements for the system. Bitzer offers training and classes on CO2 compressors, and we also have chiller braze plate glycol training from Ala-Laval.



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