Updated Thomas here, from Smart Air. I was living in China and concerned about what the air was doing to my health, so I started building DIY Air Purifiers and doing air quality tests in China. When I was doing those tests, I encountered two problems that are relevant to your question:1. Do wall-mounted air conditioners bring in dirty outdoor air?The tubes on my air conditioner led outside, so I had always presumed they brought in outdoor air. But it turns out they don't push indoor air out or bring outdoor air inside. They just recycle air indoors.But to be doubly sure, I ran tests! I waited for bad air pollution days in Beijing. (I didn’t have to wait long.) Then I tracked air quality before and after I turned on my AC unit.On average, particle counts had no change or went slightly down. You can see a video test and more info here:Does Air Conditioning Bring in Dirty Outside Air?However, that test was for particulate, and the question mentioned carbon dioxide. That brings up this question:2.

Even with the doors and windows closed, how much outdoor air is getting into our homes?If a lot of outdoor air is getting in, then carbon dioxide build-up shouldn't be a problem. I tested this in Beijing by leaving a particle counter on in my apartment while I went away on vacation for several days. All the windows and doors were closed. I also left an air purifier on a timer to turn on for two hours every day. Here's what I found when I came back:It's shocking how quickly the air became dirty again. Why is it getting dirty so quickly? Because outdoor air is constantly getting in--even in this most conservative test. I wasn't even home opening doors or walking in from outside.More info on that test here:http://particlecounting.tumblr.c...A caveat: some houses are sealed better, some are sealed worse.Conclusion: If your main concern is carbon dioxide, I wouldn't worry about pushing air out. However, I would make two exceptions:Exception 1: If you have an abnormally high number of people in the room or a very good seal around windows and doors, carbon dioxide will build up more.

Exception 2: If you have sources of indoor air pollution, like recent remodeling, smoking, or new furniture, then opening the windows can release those pollutants.Written Written Written You are talking about Wall mounted decorative unit.It does not take in or eject any outside air. It is re-circulating air inside the room. If you have bad air inside your room from breath of people, decorative/ furnishing materials or by any other means follow any of the following.Make controlled opening of window or doors to allow outside air but within limited quantity.Arrange exhaust from adjacent toilet etc which indirectly induce fresh air.Arrange a pair of vent pipe, say 32 mm PVC pipe through the wall, one at low level and the other at high level.Change over to a ducted central system which is taking care of fresh air entry and exhaust.WHAT IS A HEAT PUMP? Technically, a  is a mechanical-compression cycle refrigeration system that can be reversed to either heat or cool aInstallation for this type of system typically

consists of two parts: an indoor unit called an air handler and an outdoor unit similar to a central air conditioner, but referred to ashome ac unit replacementA compressor circulates refrigerant that absorbs andcost of window air conditioner repair releases heat as it travels between the indoor and outdoor units.central air conditioner ratings by brand HOW DOES A HEAT PUMP WORK? Think of a heat pump as a heat transporter constantly moving warm air from one place to another, to where its needed or not needed, depending on the season. Even in air that's seems too cold, heatWhen it's cold outside a heat pump extracts this outside heat and transfers it inside. When it’s warm outside, it

reverses directions and acts like an air conditioner, removing heat One advantage of a heat pump is that it moves heat instead of generating heat, giving you more energy efficiency. powered by electricity, so you can save substantially on fuelFor example, a Trane  heat pump is among the HVAC industry’s most efficient, with a rating up to 19.00  and 9.00 . Note that heat pumps are best for moderate climates, and a supplemental heating source may be needed for lower temperatures. year-round solution for home comfort, Trane heat pumps can become a key part of your matched system. An independent Trane dealer can help you decide if a heat pump system is right for you.Air conditioners and heat pumps utilize evaporator and condenser coils to move heat. Contrary to popular belief, there’s no “coolness generator” anywhere inside an A/C. The cooling comfort your air conditioner produces is created by removing heat energy from indoor air, moving it outside and then dispersing it into outdoor air.

These functions are handled by the evaporator and condenser coils. In the closed-loop system of a typical air conditioner, refrigerant circulates continuously between the indoor evaporator coil and the outdoor condenser coil. In its frigid, vaporous state, refrigerant has high heat absorbing properties. As it circulates through the evaporator coil installed in the indoor air handler, warm household air is drawn through the coil by the blower. Heat energy is transferred by the evaporator coil surfaces into the cold refrigerant, which is conveyed through an insulated line from the air handler to the outdoor condenser unit. At the outdoor unit, a compressor pressurizes the refrigerant, concentrating molecules of heat energy. The hot refrigerant gas enters the condenser coil, where it expands and condenses to a liquid. As refrigerant condenses inside the condenser coil, heat energy is rapidly released. The coil fan blowing over the condenser surface disperses this heat into outdoor air.

Back to the Beginning After leaving the condenser coil, the refrigerant circles back to the evaporator coil as a liquid under high pressure. Passing through an expansion valve, evaporation occurs and the refrigerant converts back to a frigid gas inside the evaporator coil. This process of transferring indoor heat outdoors continues as a continuous loop. Made for Each Other In today’s air conditioners, the evaporator and condenser coils are a matched set, engineered to accommodate your air conditioner's specific BTU capacity. Likewise, accurately determining the BTU requirements of your home is crucially dependent on the heat load calculation performed by an HVAC professional. When all the numbers are crunched and the components are matched, the result is maximum comfort and optimum efficiency. Feel free to contact Andrews Auld Heating & Cooling in Western North Carolina for more information about selecting and maintaining evaporator and condenser coils.