Glossary

BTU – British thermal unit. A unit of heat energy – approximately the amount of energy needed to heat one pound of water by one degree Fahrenheit.

dBA – a unit for measuring sound power or pressure, deciBel on the A scale.

Capacity – the ability of a heating or cooling system to heat or cool a given amount of space. For heating, this is usually expressed in BTU’s. For cooling, it is usually given in tons.

Compressor – the pump that moves the refrigerant from the indoor evaporator to the outdoor condenser and back to the evaporator again. The compressor is often called “the heart of the system” because it circulates the refrigerant through the loop.

Condenser – a device used to condense a refrigerant thereby rejecting the heat to another source, typically an air cooled or water cooled condenser.

Cassette – a fan coil unit that fits mainly in the ceiling void with only a diffuser plate visible, diffuses conditioned air in one, two, three or four directions.

HVAC – heating, ventilation and air conditioning.

Heat Pump Principle – The principle of using a heat pump, which is an environmental energy technology, that extracts heat from low temperature sources (air, water, ground) and upgrades it to a higher temperature, then releasesing it where it is required for heating rooms and water. A heat pumps can also be operated in the reverse order, for cooling purposes.

Inverter system – Constantly alters fan and motor speeds. This enables faster cooling of a room, and the inverter air conditioner doesn’t have to switch itself on and off to maintain a constant temperature.

kw – standard measurement of heat or power, 1kw = 1000 watts = 3412Btu/hr = 860kcal.

Load Calculation – a mathematical design tool used to determine the heat gain and heat loss in a building so that properly sized air conditioning and heating equipment may be installed.

Packaged Terminal Air Conditioner (PTAC) – A self contained heating and air conditioning system that is most commonly found in motels, aged and assisted care facilities, hotels,sunrooms and apartments.

Refrigerant – a substance that produces a refrigerating effect while expanding or vaporizing.

Reverse cycle – the reverse cycle air conditioner internally reverses its operation to provide heating or cooling, as required.

SEER Rating – The Seasonal Energy Efficiency Ratio (SEER) measures air conditioning and heat pump cooling efficiency, which is calculated by the cooling output for a typical cooling season divided by the total electric energy input during the same time frame. A higher SEER rating means greater energy efficiency.

Split System – a central air conditioner consisting of two or more major components. The system usually consists of a compressor-containing unit and condenser, installed outside the building and a non-compressor – containing air handling unit installed within the building. This is the most common type of system installed in a home.

Zoning – the practice of providing independent heating and/or cooling to different areas in a structure. Zoning typically utilizes a system controller, zoning dampers controlled by a thermostat in each zone, and a bypass damper to regulate static pressure in the supply duct.