It is especially important that your HVAC be installed up to code since almost all physical hardware devices come with environmental requirements that include acceptable temperature and humidity ranges. These environmental requirements are usually described in a product specifications document or in a physical planning guide. If your HVAC is especially extensive then a separate space, called a plenum, is often allocated to house and allow air circulation for the HVAC and any other communication cabling. This is typically in the space between the structural ceiling and a drop-down ceiling or under a raised floor. Failure to install your HVAC up to code could result in a serious design flaws within your new home.

One of the most important aspects in installing your HVAC is finding one that is size-appropriate to the home in terms of achieving the best efficiency and comfort level. Beyond the understanding of the maintenance and installation of the systems themselves, sizing the systems appropriately is perhaps one of the most difficult tasks of an HVAC contractor. If your HVAC contractor recommends a heating system that is too big or too little for your home the result will be an inefficient system that will cost more money in the long run. An oversized air conditioner may not efficiently dehumidify the air; and an oversized furnace is likely to cause a large temperature swing and create an uncomfortable climate inside the living areas within your home.

While the homeowner is generally dependent on his HVAC contractor there are several things he can do to help make sure that his HVAC is installed up to code. Some of these are:

 Contact your local gas or electrical company. They will sometimes perform a sizing calculation either for free or for a minimal charge. This will give you a different viewpoint to help you understand whether your HVAC that is being installed is the right one for you.
 Check out the references of your HVAC contractor. Do not be afraid to ask for references from other clients. Realize that this is a major part of your home and you want it done right the first time. A good contractor will follow procedures set forth by trade organizations such as the Air Conditioning Contractors of America (ACCA) in regards to appropriate sizing, and may use software programs to assist in the calculation.
 Have an independent inspection done throughout the stages of having your HVAC installed. This will help insure that the HVAC is being installed up to code before all components are installed. This also allows for any mistakes to be caught early and fixed promptly thus preventing costly delays.