Natural ventilation is the ventilation of a building with outside air without using fans or other mechanical systems. It can be via operable windows, louvers, or trickle vents when spaces are small and the architecture permits. In more complex schemes, warm air is allowed to rise and flow out high building openings to the outside (stack effect), causing cool outside air to be drawn into low building openings. Natural ventilation schemes can use very little energy, but care must be taken to ensure comfort. In warm or humid climates, maintaining thermal comfort solely via natural ventilation might not be possible. Air conditioning systems are used, either as backups or supplements. Air-side economizers also use outside air to condition spaces, but do so using fans, ducts, dampers, and control systems to introduce and distribute cool outdoor air when appropriate.
A dehumidifier is an air-conditioner-like device that controls the humidity of a room or building. It is often employed in basements which have a higher relative humidity because of their lower temperature (and propensity for damp floors and walls). In food retailing establishments, large open chiller cabinets are highly effective at dehumidifying the internal air. Conversely, a humidifier increases the humidity of a building.
These are the prices for a proper installation from a professional – as a word to the wise, HVAC systems require fine tuning and the custom fabrication of parts during installation to work properly, otherwise they will likely fail prematurely. But there are plenty of people who will do it for cheaper than this, using substandard, used, or stolen equipment (stolen from construction sites and new housing developments). Or, they are using unskilled laborers with no experience, etc. But HVAC is not a “we’ll figure it out trade;” there is a right way and a wrong way to do things. There are just too many predatory companies out there, so be careful. I’d highly recommend not skimping on your HVAC contractor. If you go cheap, you will typically pay more in the long run...and in California, that will be a lot!

Before we get to HVAC installation prices, we will first need to briefly discuss some terms, definitions, and factors that will affect how an honest HVAC installation company determines their prices. Notice that I said honest. Unfortunately, there are dishonest people out there. There always have been, there always will be, and there is a good chance that you had an experience with such a contractor, which is what drove you to read this article. I can’t teach you how to tell if someone is honest, but I can give you the knowledge to help you decide. Take a look at How to Choose an HVAC Contractor for tips on what to look for.
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.
If you are using existing ducting, it will have to be inspected. Proper ducting loses around 2% to 5% of your energy. Old, leaking ducts can lose 50% or more. A contractor will need to have the ducts inspected and replace any parts ahead of time. If you are changing the size of your HVAC system because of significant changes to your home, you might need to replace the ductwork regardless.
Duct system installation and repairs affect HVAC installation cost. If you’re installing a new forced air heating or cooling system, your home must have ductwork – if you don’t have ducts installed, a new duct system will need to be designed and installed. Your existing duct system may require air sealing to eliminate air loss, helping your new heating and cooling system operate efficiently.

You can adjust for seasons: During the summer, you can have the air conditioner stay off during the cooler morning hours and start cooling the house as everyone gets up and starts moving around. During the winter, you can have your heater stay off while you are away at work and turn on about a half hour or so before you get home so that you are coming home to a nice, warm house.
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]
Free cooling systems can have very high efficiencies, and are sometimes combined with seasonal thermal energy storage so that the cold of winter can be used for summer air conditioning. Common storage mediums are deep aquifers or a natural underground rock mass accessed via a cluster of small-diameter, heat-exchanger-equipped boreholes. Some systems with small storages are hybrids, using free cooling early in the cooling season, and later employing a heat pump to chill the circulation coming from the storage. The heat pump is added-in because the storage acts as a heat sink when the system is in cooling (as opposed to charging) mode, causing the temperature to gradually increase during the cooling season.
Compressor -- Compressors are outdoor components in your system. The compressor is the pump that circulates the refrigerants through the air-conditioner. You can hear it when it's running so you'll know if it's working just by listening. If it starts getting louder, your compressor is about to fail. If it makes no sound when it should be on, it has already failed. Compressors fail for a number of reasons. Most often they fail due to strain from another failed part such as the fan motor. Electrical storms can also damage compressors. If the sound from the compressor gets louder or if you see a decrease in performance, you should have your compressor checked. A failed compressor will not heat or cool your house.
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.
Ductwork pinging or popping. If you hear a pinging or popping sound coming from metal ductwork, this may be caused by thermal expansion or by air blowing past a loose flap of metal. Track along the duct runs, listening for the sound. If you find it, make a small dent in the sheet metal to provide a more rigid surface that’s less likely to move as it heats and cools.
Although most new homes have ducts and vents already in place, many older homes have old convection heating systems or baseboard heaters without ductwork. In such cases, you will need to install ducts and vents to provide the air conditioning with a flow system. This would be the time to explore upgrading the existing heating system as well, as it will be much cheaper to do together.
Heaters exist for various types of fuel, including solid fuels, liquids, and gases. Another type of heat source is electricity, normally heating ribbons composed of high resistance wire (see Nichrome). This principle is also used for baseboard heaters and portable heaters. Electrical heaters are often used as backup or supplemental heat for heat pump systems.
An energy recovery ventilator: This component helps improve the air inside your home by swapping it out with fresh air from the outside. During the winter months when houses are closed up to keep out the cold, the air inside becomes a handy way for colds and flu to infect an entire family. By circulating outside air inside, the health of your family will have a better chance.
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.