The VVT concept and equipment originally were developed by a division of northern Florida Carrier distributor Florida Air-Conditioning Systems, called FACS Products. This division later was bought out by Carrier Corp. The system employs computerized dampers that control the temperature in each room by opening and closing the dampers, which in turn are controlled by digital thermostats. This is the “VV” portion of the system. At the same time, the central intelligence also determines when to turn on the central system in either heating or cooling mode, depending on the need. This is the “VT” portion of the system.
It was back in the mid-1980s that I moved to Jacksonville, Fla., to serve as the national service manager at the startup of this company. And at the time we were simply working on a way to develop a better damper. However, one of the problems with the concept was that a separate thermostat was needed to turn on the central system. Where would you put it? Locating it anywhere in the central space would result in it being controlled by the damper in that room (a controller being controlled by a controller). And what if, in a large building, one room needs cooling when another room needs heating?
Well, the project of developing a thermostat that could sense the temperatures in each room was assigned to an engineer and he soon said he had developed one. But I looked at it and could see he simply was connecting several temperature-sensing probes to a single terminal, which only would provide an average reading. It wouldn’t work.
But a low-paid young technician in the back room told us he had an idea. He then went on to develop a central box that polls each of the system’s digital thermostats to determine what and how much heating and/or cooling was needed. Voila! It worked! And thus came something truly unique in our industry — the first VVT system.
Of course, that was some 30 years ago and not only have several other working designs been developed by other manufacturers, but I’m sure even the original system has gone through many upgrades and improvements since then. However, I still don’t see as many of these systems on jobs as I would expect. Why not? Because they add an additional cost and a lot of people don’t understand them. Thus, most installations end up being put in a few upscale office buildings.
On a personal note, digital temperature control along with the addition of variable heating/cooling equipment truly has improved comfort in my own house. Yet for maximum comfort in every room (the room I’m in right now is warmer than the rest of the house), not much can beat a VVT-style system.
Are they worth the money? How important is comfort? Unfortunately, too much of our industry still is affected by the old “low-bid” mentality and jobs that can easily be sold in upscale housing, institutions, hotels/motels, offices, etc., usually are not offered in fear of losing a bid even when there are no competitors.
Unfortunately, I’m afraid we are well into becoming purveyors of equipment and not purveyors of comfort. Hopefully that can change.