Explore these images and more!Hide Air ConditionerAir ConditionersTeakFence Ah, so what exactly is this hidden flaw? "My HVAC guy put a zoned system in my house and told me it was the cat's pajamas," you may be thinking about now. Or maybe your HVAC installer described it as the bee's knees, the eel's ankle, or the elephant's instep. However they described it, there's one piece they absolutely should NOT have installed. First of all, let's be precise in our language and clear up exactly what we're talking about. The word zoning is used in more than one way in the context of heating and air conditioning systems in a house. First, larger houses are always zoned. If you have a two-story house, for example, you probably have at least two thermostats — one upstairs and one downstairs. The other way that the term 'zoning' is used is to describe a single duct system attached to a single HVAC system that serves multiple zones. In most homes, each thermostat is connected to its own heating and cooling system.

In a 'zoned system,' a single heating and air conditioning system is controlled by multiple thermostats in multiple zones. "Come on, man, just tell me what the flaw is!"Depending on the needs of the house, any combination of 1, 2, or 3 zone dampers may be open and sending conditioned air to their respective zones.carrier 10 ton hvac unit If only 1 or 2 of the zones are calling for air, most air handlers will create extra static pressure because 1 or 2 of the pathways are closed off. cost of an air handling unitEnter the bypass duct, shown at right. air conditioner unit size calculatorWhen the system is running but not all zone dampers are open, the bypass duct—in theory—is supposed to relieve the extra pressure and maintain good air flow throughout the duct system.

At the Affordable Comfort conference this year, I went to a talk on zoned duct systems where John Proctor and Rick Chitwood discussed the pros and cons of these systems. Proctor's take is basically that zoned systems are horrible and shouldn't be used. Chitwood likes them and says when done right, they provide exceptional performance. On one point, though, they both agreed: Bypass ducts should never be used. The bottom line is that zoned duct systems are tricky. I do believe that Chitwood is right, but so is Proctor. I think Proctor's main objection isn't that zoned systems can't work; it's that they're done wrong so often. In the end, if you do get one, make absolutely sure the installer doesn't put in a bypass duct. Perhaps the Worst HVAC Duct Idea Ever — The Panned Joist Return Case Closed: Get Those Air Conditioning Ducts out of the Attic How to Install Flex Duct ProperlyHave you heard the term 'dry-ship R-22 unit' yet? Well, let me tell you a dirty little secret of the EPA and the HVAC industry.

It involves the environment, the costs that homeowners pay to buy and maintain air conditioners and heat pumps, and a legal loophole that's starting to look as big as the ozone hole. As I've mentioned here before, my connection to the world of heating and air conditioning contractors goes way back. My grandfather had a heating, AC, plumbing, and electrical business (Bailes Electric) in Leesville, Louisiana, and I used to spend my teenage summers going out on calls with him and my uncle all day long. (The measuring cup below, which sits on my desk, is from the earlier business he had with his brother, Russell.) One of the things we often did on calls was put the gauges on air conditioners to check the refrigerant charge. Often, my grandfather, Pappaw, or my uncle would prepare to fix a leak in the system by emptying all the refrigerant first. Back in the '70s, there were no refrigerant capture systems or regulations, so we sprayed it all right out into the air. The refrigerants of choice at the time were the chlorofluorocarbons (CFCs), which usually went by their trade name, Freon.

I did a science fair project on CFCs and their effect on our atmosphere in 1978. Turns out, the stuff migrated up to the stratosphere, where it has a tremendous appetite for the three-atom form of oxygen, called ozone. That wasn't so good because ozone in the stratosphere has a tremendous appetite for ultraviolet (UV) rays from the Sun. UV rays, you're probably aware, have a tremendous appetite for skin cells, causing cancer when we get too much of it. You also may have heard reports of sheep going blind in Chile because of the extra UV, but it turned out to be a local infection instead. Still, CFCs destroy ozone and that leads to problems. The science is solid. Well, in 1987, the Montreal Protocol began the phaseout of CFCs and a plan to move to better and better refrigerants. (Better in terms of their effect on the ozone layer, that is.) In the early '90s, CFCs were phased out and replaced with the HCFC R-22 in air conditioning systems. At the end of 2009, the US banned the production of new air conditioners and heat pumps that used R-22, and the more benign HFC R-410A was set to become the only game in town.

So, the US EPA gave manufacturers and contractors some wiggle room, of course. They couldn't tell the manufacturers they had to destroy all their unsold units in 2010. They also couldn't just strand all the people out there who already had R-22 in their air conditioners. As a result, manufacturers could sell their stock of R-22 units, continue to make parts to maintain the existing systems, and keep making R-22 refrigerant. If you go to the EPA's website to read about the phase out of R-22, you'll find this statement: [H]eating, ventilation and air-conditioning (HVAC) system manufacturers may not produce new air conditioners and heat pumps containing R-22. Do you see the loophole? As long as they ship the units 'dry,' manufacturers concluded, they could continue to make and sell air conditioners and heat pumps designed to use R-22. Hence the term, 'dry-ship R-22 unit.' As it turns out, a surprisingly high percentage of new systems are in the 'dry-ship R-22' category.

Recently I was speaking with an HVAC supply house executive who told me that these loophole escapees make up about 30% of the units they sell. The author of an article on dry ship R-22 units on the Contracting Business website interviewed his local suppliers and found the following: One supplier told me it was about even. Several more said they sell slightly more dry units than R-410a systems. One supplier told me they sell four to five times as many dry units as complete systems. Yes, some of these might actually be used as they're intended — as replacement components in existing systems — but I think most people in the industry know that the majority of these dry-ship R-22 units are new installs. From what I hear, it was a manufacturer of low-end equipment that first walked through the loophole and starting making dry-ship R-22 units. When the EPA didn't step in to close the loophole, the race was on. Both the EPA and the HVAC industry share the blame. The makers of higher-end equipment don't want to give up market share to those on the lower end who can exploit a bigger price difference.

The dealers and the contractors, likewise, have to compete, and the EPA has forced their hand by allowing this situation to continue. Both sides are to blame: the HVAC industry for exploiting the loophole and the EPA for not closing it. The EPA is definitely more to blame because they could have shut this down as soon as it became apparent. They still can but are dragging their feet. Carrier has petitioned the EPA to close the loophole. , explained it this way: “As an industry, we were prepared for the R-22 transition — manufacturers had invested in the new technology and contractors had invested in technician training, as well as in helping consumers prepare for this transition. The loophole threw all that up in the air.” I don't understand all the forces at work in the meeting rooms of those HVAC manufacturers, but I wish they’d all take a principled stand and refuse to play this game. Perhaps if the bigger names did so, they could shame any company that exploited the loophole.

As long as the manufacturers keep making the dry-ship R-22 units, though, the downstream companies—the dealers and the contractors—feel the pressure to play the game, too. Not all of them, however. I know of one contracting company that, out of the more than 2000 condensers they've installed since this came up, only about 10 have been dry-ship R-22 units. If you're in the market for a new air conditioner or heat pump, you absolutely need to make sure that you don't get a new system using what should be an illegal refrigerant for new systems. If the contractor tells you that the R-410A system will be more expensive, ask him or her how much it'll cost you to maintain the system. If they tell you anything other than that it'll get very expensive as we get closer and closer to the ban of R-22, steer clear of them. Don't fall for this! It's a dirty little secret in the EPA and the HVAC industry with plenty of folks in the industry and government willing to justify jumping through the loophole.