Known in the trades as Heating, Ventilation and Air Conditioning (HVAC), this home service industry keeps your climate controlled and family comfortable. An HVAC unit means central air, central heat, central convenience. To keep your home fit for human habitation throughout New York's stifling summers and icy winters, an HVAC system, expertly installed and maintained, will keep you smiling smugly at whatever Mother Nature throws your way.
- An HVAC Primer
- On Cost and Contracts
- On Service
- What Should I Look for in an HVAC Professional?
- Credentials Please
- Questions Your HVAC Contractor Will Ask
All air conditioning (A/C) systems operate under the same principle: a fan sucks in your home's warm air across coils that contain a refrigerant (freon), and the cooled air is then blown into the room. Central A/C operates with two principle components: a condensing unit and evaporator coil. The condenser pressurizes the refrigerant so that it cools before it is sent to the evaporator coil. Heat is released in the process, so this unit must be located outside of the home. The cooled refrigerant is then circulated to the evaporator coil, where a blower moves warm air collected from the plenum (the dead space above the ceiling) across the cooled coils to dehumidify and cool it. Finally, this cool air is directed via duct-work back into the rooms. (And you thought an air conditioner just contained a fan and a block of dry ice!)
Heating is supplied in one of three ways: forced air, hydronic or steam. In the forced air system, air is heated as a blower moves it through your furnace or a heat pump and distributes it via duct-work through the home. While a furnace heats the air through burning natural gas, wood or coal, a heat pump functions like an air conditioner with the refrigerant cycle reversed. Chill is released at the condenser and warm air produced at the evaporator coil. The air is further heated through electric heating coils at the blower. In the hydronic system, water is heated via gas or electricity in a boiler and distributed to radiators. The steam system works similarly from a boiler, with steam distributed directly to radiators rather than water.
Believe it or not, it's not the air that makes your room a delightful temperature. It's math. Maybe you thought there would be no math involved, but you don't want to glaze over when your mechanical man starts spouting acronyms such as BTU, EER and CFM. All of this has to do with the efficiency of your system. Heating is measured in BTUs (British Thermal Units). Cooling is measured in tons. The capacities of furnaces, boilers, heat pumps and air conditioners are determined by how many tons or BTUs they carry. The standard for an 800-square-foot area is 30,000 BTUs of heat and one ton of air conditioning. Obviously, the bigger the space, the more capacity you will need.
The EER, or Energy Efficiency Rating, measures the relationship between space and the energy needed to properly condition its climate. equipment with higher EERs will properly condition more space with less capacity. The higher the EER, the higher the quality (and cost) of the equipment and the less your energy bills.
Ducts are a significant aspect of HVAC system efficiency. Obviously, you want to have as direct a path as possible between the heat/cool source and the space it's to condition. If the ductwork is too small, the run extending from the source too far or if there are too many bends and jogs, the airflow will suffer. Designers specify the amount of CFMs (the measurement of the airflow through your ductwork) necessary to properly condition a space. If this isn't met, the efficiency of your system is compromised because your equipment has to work harder than it should for a given space.
As in any other trade, you'll be charged for labor, materials and a 10 to 20 percent mark-up for overhead and profit, plus tax. Make sure the estimate includes any other associated work—electrical, plumbing, plaster—that may be necessary for the installation if you expect someone to do it. All makes and models of equipment should be spelled out on the bid proposal. If your HVAC professional is fishing for a service agreement to cover the gaps in the warranty, see if you can get him to discount his price if you accept. ItÍs okay to sign off on the bid proposal to execute the work, but it should refer to drawings (best generated by an engineer as opposed to a sketch on the back of a napkin) and they should be attached. Clean-up, transportation (possibly parking, too, in New York City), commencement and completion dates, payment schedule, change order procedure, licensing and insurance information should all be included in the contract, if not on the bid proposal. He should be responsible for the cost and time of obtaining permits.
There are a lot of variables in HVAC, so warranties count. One year for parts and labor is typical. You should get your mechanical contractor to do a check-up once a year. Treat him like a dentist—you wouldn’t neglect to brush your teeth between check-ups, and you shouldn’t neglect your filters between visits from the HVAC man. Change them once a month; dirty filters will degrade the system’s efficiency. It’s easy to do; just get a lesson before the installer leaves. Also know where the gauges and valves are and how to read them. And try to maintain a good relationship with your mechanical man after the job. You don’t want to have to pay someone else to become familiar with your custom-designed, intricate home system.
Your HVAC service provider is essentially putting the lungs into your house, and you don't pick your surgeon based on a nudge and a wink. Talk to general contractors and ask who they recommend. Know that HVAC invariably involves plumbing and electrical work. You want to know whether the person you hire can handle the work necessary to make the system function, or if you'll have to bring in other trades to assist. If there is going to be work in and around your existing space, find out how clean and careful he is. Your research into a good HVAC person will be more effective if you learn a few things about how these systems work. There's more to HVAC than thermostats. Learn the language so that when the installer asks if he can cut ducts in your apartment, you won't immediately report him to People for the Ethical Treatment of Animals.
HVAC is a complicated field. With all the inter-trade coordination, mechanical speak and math involved, your mechanical contractor's civility and credibility must be backed up with the required licensing and insurance. This includes coverage for general liability, worker's comp and property damage.
Manufacturers and distributors—a great source of recommendations—will allow only licensed mechanical contractors to purchase certain HVAC equipment. States insist on licensing to handle freon. In fact, every individual employed by a mechanical contractor should hold a general license to work. Make the usual rounds by checking up with the New York City Department of Buildings at (212) 312-8217.
- Where is the interior unit going to go? Large utility room? A closet?
- Do you have permission to place a condenser outside? From the co-op? The city?
- Is there enough ceiling height to add ductwork?
- Where do you want the controls?