I think that the only thing Carrier has missed the boat on here is that they used a proprietary protocol rather than a Standard protocol, such as BACnet or LonTalk. The fact is, many residential systems are used with commercial systems, as in office areas in factories, so any new commercial system that is installed with a proprietary protocol is about as short-lived as equipment that uses R-22 as a refrigerant.

Of course, the top Carrier system uses R-410A (which they have dubbed Puron) as a refrigerant, and their system uses a 2-speed compressor and a variable-speed fan motor for quiet operation and top efficiency. The interesting thing about the compressor they are using on this system is that it is Bristol's dual-capacity unit, which pumps with two pistons when it is running in one direction, but with just one piston when the motor direction is reversed. Three years ago, when I first wrote about this compressor, I didn't think it would be a successful competitor, because it requires a sophisticated digital system and two contactors to make it run, so I thought it would be more expensive than similar compressors from other manufacturers. However, the person I spoke to from Carrier told me that they are very satisfied with its cost, its operation, and its reliability.

Another new air conditioner that I was very impressed with at the Expo was the top-of-the-line condensing unit in Nordyne's Maytag brand of HVAC products (all their brands were there with different but nearby booths). It, too, has a 2-speed compressor and a variable-speed companion furnace or airhandler. However, it still uses conventional 24-volt technology.

What really impressed me about this unit is that its condenser coil is wrapped with a stunning stainless-steel cover that is not only very attractive, but extremely durable, and will hold its finish well. And the compressor they are using is the same one (a scroll design) I wrote about last year, that comes from Copeland. It's the one that achieves its capacity reduction with a simple solenoid valve that allows gas to bypass the compression cycle.

I found more interesting compressor technology when I got to the Tecumseh booth and heard that this company is trying to develop a new air-conditioner design using CO2 as a refrigerant! I didn't think that was possible and wanted to ask more questions, but none of their engineers was available at the booth when I got there. However, wouldn't that be an interesting innovation?

Speaking of refrigerants, a representative of one of the Chinese companies that was exhibiting told me they are selling air conditioners in Europe that use propane as a refrigerant. And when I asked, “Isn't that explosive?” I was told, “No, it's just flammable.” I don't know about that one.

In the line of “Where would you find one of those?” I noted a new condensing unit from National Comfort Products of Bensalem, Pa., that is specifically designed to mount flush into the walls of apartment houses. They are perfectly rectangular for a tight fit and are available with attractive optional designer grilles. Of course, this system requires copper tubing and a separate furnace or airhandler.

And last, I know that you're probably not in the fireplace business, but everyone should see the electric heater from Globaltec Fireplaces in Burnaby, British Columbia, Canada. These are, once again, electric heaters, that are available in a full line ranging from Franklin Stoves to the most chic of modern wall-mounts. I honestly couldn't tell they weren't gas fireplaces. Perhaps the flames look just a wee bit too good and too realistic, but I want one - and I live in a place where we seldom need electric heaters.

In next month's issue, I will discuss some of the interesting options and add-ons that I found at the 2005 AHR Expo.