Editor's Note: CR4 thanks Larry Butz of GEA Consulting for contributing this blog entry.

Just when we were getting used to R-404A, 134a, 410A and a few others we decide that that's just too simple. First we get the new HFOs-1234yf and 1234ze that have lower GWPs to meet European carmakers needs to replace R-134a. This seems to have reactivated the "dial-a-blend" concept from the late 1980's from which blends such as R-410A , 404A and 407C emerged.

Today's staggering array of alternatives were partially exposed at the recent ASHRAE Winter Conference with code names such as DR-4 and DR-5 or N-40, l-20 or L-YF, each being a customized combination to yield a specific GWP in a particular application. Obviously, all other characteristics vary as compositions change. Capacity, efficiency, flammability, toxicity, high ambient performance, cost, etc all vary as well as our need to remember what the differences are between azeotropic and zeotropic mixtures and how that impacts system design, servicing and handling requirements.

With "dial-a-blend" we just optimize for each unique application, part of the world, technology type, etc. The race is on to determine winners and losers in the latest version of refrigerant wars. It should be interesting.

Note: For those who have not seen our quarterly newsletter I invite you to check out the last issue as well as past issues for news and information relevant to the Global HVAC industry on these topics:

• Global Warming/Climate Change
• Ozone Depletion
• Refrigerants
• Global Water Shortage
• Clean Energies
• Green Buildings

In this most recent issue, I provided the following commentary on the new phase we are entering with a whole new cast of characters.

- Larry Butz