AFUE - Annual Fuel Utilization Efficiency
This is the rating that all heating systems are given by the federal government, and rates the efficiency of each manufacturers system. It is similar to the EPA ratings for gas mileage on your car. The higher the AFUE rating, the higher the efficiency, and therefore, the lower your heating bill. Gas systems run as high as 94% and oil as high as 86% AFUE.

Boiler
A boiler produces hot water to heat a home using hot water baseboard, European style panel radiators, or to circulate hot water to hydro-air air handlers.

BTU’s - British Thermal Units
A measurement of heat and cooling used in the heating and cooling business. All equipment is rated in BTU’s. The higher the number, the more heating or cooling you have. One BTU is equal to the heat a single wood match produces when burning.

Condensing Unit
This is the outdoor unit that contains the a/c compressor (just like your refrigerator), that produces the cooling for your central a/c system.

Dehumidifier
This device, located in the basement, dries out a humid basement in spring, summer and fall. Ideally, it should be installed to allow a hose to drain the moisture into a sump in the basement, precluding daily emptying of the dehumidifier bucket.

EAC’s - Electronic Air Filters
These are a step above media filters in filtration performance and can even filter cigarette smoke from the air when attached to a central heating or cooling system. EAC's typically cost $600 to $800 installed.

ERV - Energy Recovery Ventilator
This device is similar to an HRV except it also recovers the moisture in winter that would ordinarily be lost to the outside. In summer, it brings in fresh air while rejecting the excess moisture to the outside. This allows your central a/c system to work easier by not having to dehumidify the hot humid air being introduced by the ventilator.

Furnace
This is a popular system that produces warm air to heat the home. Metal ductwork distributes warm air from the furnace to floor and ceiling registers throughout the house.

Geothermal Heat Pumps
These are used for cooling, and in some cases heating homes throughout the country. They use very deep wells (typically 900 to 1,500 feet deep) to either reject the a/c system heat in the summer, or extract heat from the earth in the winter.

HEPA - High Efficiency Particulate Filter
This is similar to the air filters that hospitals use, but on a smaller scale for homes. They can be free standing devices in a room, or whole house devices attached to a basement warm air heating system. This allows all rooms to get the benefit of the filtration it produces.

HRV - Heat Recovery Ventilator
This device, located in attics and basements, brings fresh air in to the home while exhausting the same volume of air, and recovering 75 to 80% of the heat. It is more efficient and comfortable than opening windows in winter.

Humidifier
This is the device that is attached to the basement warm air furnace or hydro-air air handler, and produces moisture for the home in winter. Typically, 35% to 45% relative humidity is comfortable in the winter.

Hydro Air
This is a system whereby a hot water boiler produces hot water, and pumps it into a special air handler with both heating and cooling coils inside (they look like car radiators inside the air handlers). It looks like the indoor air handler of a central a/c system and produces both warm air from hot water to heat the home in winter and cooling in summer.

Media Filters
These are used on all warm air heating and central cooling systems to filter the air to a high level. They are ideal for families with allergies. Media filters typically cost $300 to $400 installed.

Registers, Grilles and Diffusers
These are the “grilles” on your floor, walls and ceilings that bring warm or cool air into each room.

SEER - Seasonal Energy Efficiency Ratio
This is the ratio of electricity consumed by the a/c or heat pump system compared to the energy it produces. The federal government rates the equipment. The higher the SEER number, the more energy efficient the system is. Currently the minimum for a/c systems is 13 SEER.