The HVAC (heating, ventilation, air conditioning) subcontractor is one of three "mechanical" subs (plumbing, electrical, HVAC) that will need to be hired to build your home. If you are building the home yourself, check with your local building department to verify you are allowed to do the work of these three trades. Most places require this work to be signed off by a licensed professional.
All HVAC systems have the following parts. Each component relies on the others to function properly and efficiently.
Furnace: The furnace takes up the majority of the space in an HVAC system. It is usually in the basement or attic and its an important component. The furnace moves air from the heat exchanger into the air ducts. The furnace is sometimes confused with boilers, but they are different HVAC appliances.
Heat Exchanger: This is not part of the furnace. It is located inside the furnace, but the heat exchanger has its own capabilities. It adds heat to the incoming air from the combustion chamber.
Evaporator Coil: This HVAC part is also in the furnace, but handles a different job. Refrigerant runs through the evaporator coil. The coil absorbs heat from air passing over it. The now cold air blows through the air ducts throughout your home.
Condensing Unit: This is like the evaporator coil but for an outdoor HVAC unit. Inside the cube-shaped unit, the condensing unit exchanges heat with air that passes over it. Unlike the evaporator coil, the condensing unit gives off heat.
Refrigerant Tubes: These metal tubes connect the evaporator coil with the condensing coil. This means the refrigerant tubes connect the indoor and outdoor HVAC units. The tubes contain cooling refrigerant under a wide range of temperatures.
Thermostat: This is the part of the HVAC system that you are most familiar with. This small appliance is on a wall of the main level of your home. Depending on what temperature you set it at, you can turn on the air conditioning or heating system. A programmable or "smart" thermostat fine-tunes your homes' temperature even if you are not there. That means you can save money on your energy bill.
Ductwork: The air ducts move air throughout your home. Air comes into the HVAC system through certain sections of the ductwork. It is distributed to rooms through other sections.
Vents: As the air travels through the ductwork, it enters the room through vents. Rectangular covers on the floor or ceiling direct and take air.
Heat Pump: During warm months, the heat pump takes the heat from the inside to the outside. During cold months, it does the opposite.
Before you begin the HVAC rough-in, set up an appointment between your HVAC sub and your plumber. This meeting should take place after the home is framed but before either of their work begins. This is a great idea because it allows open discussion of where the drains and ductwork will be located. This is a pro-active way to reduce conflict between these mechanical trades. This is especially needed if your house plan features open concepts. When walls are eliminated, space for these items become scarce. Avoid installing these items on exterior walls at all costs! Ductwork installed on exterior walls and in unconditioned space will be inefficient, may create condensation and mold and will leave cold and warm spaces in your new home.
According to the U.S. Environmental Protection Agency, indoor air quality is four to five times worse than outdoor air quality. Indoor air has many sources of pollution, including pet dander, cooking, remodeling projects, and off-gassing of materials like cabinets or carpeting.
To improve indoor air quality in your home, it's critical to constantly remove polluted air and introduce fresh air. Thus, proper ventilation is imperative.