All About HVAC
 
The term HVAC is similar to the abbreviation R.S.V.P.- we know the general meaning but are hard-pressed to say exactly what the letters stand for. For the record, HVAC stands for heating, ventilating and air conditioning. That means an HVAC system heats and cools your home, plus filters, cleans, humidifies and de-humidifies the air in it. Whether you're moving into an existing home, building a new one, or renovating, it's important to know your components. To get the best setup for your needs, read on for details.

Big Picture Concerns
When choosing an HVAC system, work with a quality contractor. This professional will do a "load calculation," which means they consider the house's square footage, insulation and the number of windows, plus your area's climate to determine the best equipment for your home. There are three main concerns.

Size. It does matter. And bigger isn't always better. A system that is too big switches from on to off more than necessary, wasting energy and money.
Efficiency. Different combinations of equipment create different rates of efficiency. An HVAC contractor can work with you to design an efficient and cost-effective system.
Warranty. A 10-year parts warranty is fairly standard on heat pumps and air conditioner compressors, as is a 5-year warranty on digital thermostats. But the warranty to look for is one that ensures parts and labor for at least one year. Larry Taylor, president-elect of the Air Conditioning Contractors of America association has some caveats about warranties. "An extended warranty does not necessarily mean everything is covered," he says. "Consumers need to read the warranty."

Outdoor Unit
An HVAC's heat pump and air conditioner compressor are the building blocks of the system, and are likely to be combined as one unit. This unit is sized in "tons," which pertains to its power. Typical single-family homes are served well by units between two to five tons. A unit's SEER (seasonal energy efficiency ratio) rating reflects its efficiency, and the higher the number the better. A rating of 10 is standard while a rating of 15 or more means high efficiency. Heat pumps also have a HSPF (heating seasonal performance factor) rating, the industry minimum being 6.8.

Ductwork and Vents
In a forced-air system, heated or cooled air is powered by a mechanical blower and flows through the house via ducts and vents. An HVAC contractor can determine if your home's existing ductwork and vents are adequate to effectively distribute the air or if additions to the system are needed.

Thermostat
With mechanical thermostats, you line up a lever with the desired temperature. It doesn't matter if it's a degree or two off (at least not until you get your bill). On the automated side, today's digital thermostats are much more accurate. Some even are programmable and enable you to pre-set temperature changes or set different temperatures or cycles for different areas of the house. This can add up to big savings.

Cost
The cost of the right comfort system varies. There are factors beyond the basic - size of home, efficiency desired, existing equipment - that affect price. "Even with two identical houses built side-by-side by the same builder, the cost of HVAC systems will likely be different," says Larry Taylor. "One family may have several children which probably means their doors are opening and closing more often, they have more dust and more germs. The other family may have pet hair to contend with and a home office full of equipment that generates more heat in that one room."

Installation
Generally, it's smarter to design and install a complete system with the help of a contractor. Systems constructed piecemeal tend to be less efficient and more costly. "It's like building a car one piece at a time as opposed to buying it whole. You need to be concerned with the parts working together properly," says Taylor.