Asking how much an HVAC installation costs is kind of like asking, “how much does a new car cost?”  Well, are you buying a Porsche or a Honda? Is it a 911 or just a Boxster, and are you going to get the leather seats? Likewise, are you going to get a Carrier or a Goodman air conditioner? Does the ductwork need to be replaced? These are all questions that will affect your HVAC installation cost, so let’s take a closer look.
Here in Atlanta we get 6 to 10 $49 coupons in the mail weekly…I have always consider them a complete scam….just had my master bathroom& bedroom and guest bath completely remodeled down to the studs…Had my 3 returns nearest the area sealed to prevent sheet rock dust to spread…it worked and I personally cleaned all 7 returns when a 5 HP , new Rigid shop Vac($99 from HD)…took one hour and I found little evidence that “I need my ducts cleaned” Had quotes from $400 to $600…I use the best air filters for my air handler and change it every 2 to 3 months…..any dust is trapped in it and I believe the Air Duct folks are all cons….
The next step was cleaning the cold air returns. He found a good spot to drill an 8” hole for his vacuum hose. The procedure matched the other air ducts except that when he finished at the two cold return registers he drilled several holes in the cold ducts in the basement and blasted air into them. Because of our houses age and the upgraded return system, I noticed that the main sheet metal return duct had no top but was just butted up against the ceiling in the basement. When he blasted air in, dust and crap shot out the edges along the ceiling. Once he finished that he removed the filter and “swept” out anything at the bottom of the return with his hand into the 8” hose.

My 48 yr old house (mine for the last 4 yrs) has considerable dust in the return plenum (fiber duct). I’m remodeling and recently re-sealed the return plenum AND the site-fabbed transition built when the new unit was installed, 2013. The return was leaky no doubt drawing musty, dusty air from the crawl space due to the Red-Neck fab & seal job! Pitiful craftsmanship! It took me 7 hours to fix the new transition piece. Anyway, the dust in the house is the same “color” as whats in the return duct and I’m getting way too much & too often in the house. I’ve also cleaned my coils, which were not that dirty.
EPA does not recommend that air ducts be cleaned except on an as-needed basis because of the continuing uncertainty about the benefits of duct cleaning under most circumstances. EPA does, however, recommend that if you have a fuel burning furnace, stove, or fireplace, they be inspected for proper functioning and serviced before each heating season to protect against carbon monoxide poisoning. Some research also suggests that cleaning dirty cooling coils, fans and heat exchangers can improve the efficiency of heating and cooling systems. However, little evidence exists to indicate that simply cleaning the duct system will increase your system's efficiency.
Demonstrate visible evidence of microbial growth in your duct work. Some service providers may attempt to convince you that your air ducts are contaminated by demonstrating that the microorganisms found in your home grow on a settling plate (i.e., petri dish). This is inappropriate. Some microorganisms are always present in the air, and some growth on a settling plate is normal. As noted earlier, only an expert can positively identify a substance as biological growth and lab analysis may be required for final confirmation. Other testing methods are not reliable.
Installation: Replacement is quite easy, especially when an old refrigerant line set can be used. If the set is worn, it’s much better to pay the extra $400-$600 to replace it rather than risking it leaking later. When your AC loses refrigerant, you lose your cool air and the compressor is at risk of failing. A new installation means installing a coil in your furnace or air handler, running the line set between it and the coil in the condensing unit and adding refrigerant, if needed. Most ACs come pre-charged for 20-30 feet of line. If the line set is longer, a small amount of refrigerant is added.
My point is that the brand of equipment you choose is going to affect your HVAC installation cost greatly. People often call us for an air conditioning installation job and say, “I would like to install Carrier equipment.” Now, if you are a future client of ours, I’ll have to warn you – I can be a bit of a smart-ass. Why can’t work be fun? Besides…I was in the Navy for 11 years, what do you expect. 
Demand controlled kitchen ventilation (DCKV) is a building controls approach of controlling the volume of kitchen exhaust and supply air in response to the actual cooking loads in a commercial kitchen. Traditional commercial kitchen ventilation systems operate at 100% fan speed independent of the volume of cooking activity and DCKV technology changes that to provide significant fan energy and conditioned air savings. By deploying smart sensing technology, both the exhaust and supply fans can be controlled to capitalize on the affinity laws for motor energy savings, reduce makeup air heating and cooling energy, increasing safety and reducing ambient kitchen noise levels.[29]
The heat pump gained popularity in the 1950s in Japan and the United States.[13] Heat pumps can extract heat from various sources, such as environmental air, exhaust air from a building, or from the ground. Heat pumps transfer heat from outside the structure into the air inside. Initially, heat pump HVAC systems were only used in moderate climates, but with improvements in low temperature operation and reduced loads due to more efficient homes, they are increasing in popularity in cooler climates.
Roof-mounted systems have the heating and cooling systems in one cabinet. Sometimes called "gas packs" (if the heater uses natural gas), they typically cost less than a comparable split system. In dry regions, most homes originally had "swamp-coolers" installed. When replacing them with HVAC systems, it's often cheaper to use existing mounts and ducting.
If not properly installed, maintained and operated, these components may become contaminated with particles of dust, pollen or other debris. If moisture is present, the potential for microbiological growth (e.g., mold) is increased and spores from such growth may be released into the home's living space. Some of these contaminants may cause allergic reactions or other symptoms in people if they are exposed to them. If you decide to have your heating and cooling system cleaned, it is important to make sure the service provider agrees to clean all components of the system and is qualified to do so. Failure to clean a component of a contaminated system can result in re-contamination of the entire system, thus negating any potential benefits. Methods of duct cleaning vary, although standards have been established by industry associations concerned with air duct cleaning. Typically, a service provider will use specialized tools to dislodge dirt and other debris in ducts, then vacuum them out with a high-powered vacuum cleaner.