Clean air delivery rate is the amount of clean air an air cleaner provides to a room or space. When determining CADR, the amount of airflow in a space is taken into account. For example, an air cleaner with a flow rate of 100 cfm (cubic feet per minute) and an efficiency of 50% has a CADR of 50 cfm. Along with CADR, filtration performance is very important when it comes to the air in our indoor environment. Filter performance depends on the size of the particle or fiber, the filter packing density and depth and also the air flow rate.[30]
R-22 Freon is being phased out & isn't readily available. So the service company may only purchase as needed and the lack of availability would make their cost high. But, as long as they can get it, whatever the cost, unfortunately, is less expensive than replacing the A/C. Which will be the case eventually since it's no longer manufactured or sooner as in my case with a not so old a/c that sprang a leak, that would have been just a repair, but since it uses R-22 the whole unit has to be upgraded(replaced).  
They are also often harder to install. A proper location on the roof must be selected that can support the weight of the unit. Then a platform must be built and a drain pipe for the unit must be run along the roof to avoid problems with mold and corrosion. A crane must be used to lift the unit onto the roof while a team guides it into place and hooks it up.

At the state level the rebates are still substantial. For example, switching to a zoned system can get you a $100 rebate from various A/C companies, and state rebates are also included. In Pennsylvania a high-efficiency air conditioner alone can get you up to $300, and a high-efficiency complete HVAC system can see up to $1000. Maryland's incentives get up to $1,250, with a $100 rebate on a tune up of an existing system.

So HVAC sent Tony Diaz to my house. I was at work so he was subjected to the most excruciatingly exacting woman on the planet (my wife). Tony impressed her with his friendliness, professionalism and the obvious jouneyman-level knowledge of his craft. He found literally --burnt-out-- parts in our system and replaced them. It cost us a bit but I know enough about the parts to see there was no gouging on the parts and a fair rate for the labor. It wasn't cheap but it was fair and worth every dime.
Furnace Circuit Board -- The furnace circuit board controls a variety of functions. It not only handles the regular operation of the furnace, it also monitors the furnace's various safety circuits. Over time, vibrations from the furnace can weaken solder point and cause them to separate. Dirt and debris can cause short-circuits that damage the board. Failure of the circuit board can cause a variety of effects ranging from the fan not turning on to the complete shutdown of the furnace.

Central, "all-air" air-conditioning systems (or package systems) with a combined outdoor condenser/evaporator unit are often installed in North American residences, offices, and public buildings, but are difficult to retrofit (install in a building that was not designed to receive it) because of the bulky air ducts required. (Minisplit ductless systems are used in these situations.) Outside of North America, packaged systems are only used in limited applications involving large indoor space such as stadiums, theatres or exhibition halls.
Many central air conditioning systems use the furnace blower to distribute cool air through the home. If you do not have a central heating system installed, it is cost-effective to install a heating and air conditioning system at the same time. If you already have central heat, you can use the existing fans and duct system for the central air system.
Air conditioning units are prone to the pitfalls of wear and tear. You can prolong this, however, with proper maintenance procedures. Without regular maintenance even an immaculate AC installation in Fort Smith, Arkansas cannot guarantee performance. Our maintenance service is thorough, leaving no area unattended. If there’s a problem, we’ll catch it early and prevent avoidable breakdowns and costly repairs.
ISO 16813:2006 is one of the ISO building environment standards.[31] It establishes the general principles of building environment design. It takes into account the need to provide a healthy indoor environment for the occupants as well as the need to protect the environment for future generations and promote collaboration among the various parties involved in building environmental design for sustainability. ISO16813 is applicable to new construction and the retrofit of existing buildings.[32]
Cost Factors: The size of the unit, its efficiency and it’s single-stage, two-stage or variable-capacity are the top cost factors. Features like communicating technology and improved dehumidification performance also affect the price. Learn more about communicating technology here including the pros and cons, before being agreeing to a communicating system.
The HVAC installation costs below are based on residential installations only, and are priced for a single unit. Two units should be about twice the price. “Tim, shouldn’t there be a discount?” If people start giving you discounts, they are probably charging you too much to begin with.  That’s our philosophy anyway. Twice the parts and time should be twice the price from a fair contractor. The prices listed include component parts (with warranty), labor, and all materials for a complete HVAC installation.
Do you live in a historic home and want to tie your new system in to work with existing features? The price will go up to do the job right. All of these things add up to slow down the HVAC company, which takes more time, which costs more money for labor and parts. This is especially true if they are a legitimate company which is licensed, bonded and insured. Simply put, this is the “X-Factor” in your HVAC installation cost. Again, you could get people to do it for cheaper…but you won’t be happy with the results, I promise.

Installation: The old furnace is disconnected from the ductwork plenum, exhaust flue, gas and electrical hookups. In most cases, a new plenum must be made onsite or ordered from a local sheet metal fabricator. A new vent might be required too. The furnace is set and reconnected. Adjustments to the blower fan speed and burner are made to optimize furnace performance for your home and climate.
Air conditioners can create a lot of water because they remove moisture from the air. To get rid of this, they have a [usually plastic] drain pipe that comes out of the side of the air handler. Over time, algae can block this pipe and, when it does, the AC won’t work. In fact, some condensate drains have a float switch that won’t let the AC run if water backs-up. Water can also puddle around the unit or flood the area. To deal with condensate problems, please see Air Conditioner Leaks Water, below.