Angie's LIST Guide to
Glossary: Heating and cooling

A collection of terms and definitions relating to the purchase, installation and maintenance of home heating and cooling equipment.

Air exchange - Energy Star

Air exchange rate: Air exchange rate is the rate at which air from outdoors replaces the air that exists inside a structure. Air exchange rate is measured in two ways.

Air changes per hour, or ACH, is defined as the number of times outside air replaces inside air within an hour. Cubic feet per minute, or CFM, measures the volume of outside air that replaces inside air.

Backup furnace: A backup furnace is installed as a secondary source of heat, usually in homes that rely upon geothermal systems or solar energy for primary heat sources.

British thermal unit: Most often referred to as BTU, the British thermal unit is a measurement of the amount of heat that is needed to raise the temperature of one pound of water one degree.

CFM/cubic feet per minute: A measurement of the volume of air that flows through any given space in one minute.

Combustion chamber: Combustion describes a series of chemical reactions that cause the release of heat. A combustion chamber in a furnace is an enclosed space where combustion takes place.

Condenser coil: The condenser coil is located within an air conditioner or heat pump. As the fan blows in air from the outside, refrigerant circulates through the condenser coil.

Outside air is then either released or collected, depending upon the unit’s current function.

Cooling capacity: The term cooling capacity is used in reference to air conditioning systems. It is a measurement of the amount of heat that the AC unit can remove from a room in a one hour time frame.

Draft: Draft refers to the movement of heated air, or combustion air, through a chimney.

Energy Star: Created by the Environmental Protection Agency, the Energy Star Program rates energy efficient products that are used in homes, including heating and cooling systems.

Energy Star rating - Heat load

Energy Star rating: Displayed as a comparative guide for purchasing new appliance, including heating and cooling devices, the Energy Star rating of a product is determined by how energy efficient that product is.

Rating guidelines vary from item to item. In order for a cooling system to be Energy Star qualified, it must be at least 10 percent more energy efficient than the minimum government standard.

Flue: The flue is the structure through which heated air, or combustion air, moves before they are released from indoors to outdoors.

Forced air system: A forced air system is a type of heating system. With a forced air system, rooms are heated by air that is blown with fans through ducts.

Freon: Freon is an organic compound that is used as a coolant in HVAC systems. The name Freon is a registered trademark of DuPont, but is often used interchangeably with coolants of the same type such hydrochlorofluorocarbons.

Fuel efficiency: Fuel efficiency refers to the ratio of amount of heat produced in regards to the amount of fuel that is used.

Heat exchanger: The heat exchanger is located inside a furnace. Its function is to transfer heat into the air, which is then pumped throughout the building structure.

Heat loss: Heat loss refers to the heat that leaks from the inside of a building to the outside, an important consideration when purchasing new HVAC equipment or making energy efficiency improvements.

Heat pump: A heat pump moves heat either into or outside of a building structure. To heat a home, a heat pump pulls air from outdoors, heats the air and moves it through rooms via ducts. To cool a home, air is removed from building structures and pushed outside.

Heating load: Heating load is a measurement, usually measured in BTUs, of the heat flow needed to keep a stable temperature indoors.

HEPA - Negative pressure

HEPA: An acronym for High Efficiency Particulate Arrestance, a type of air filter.

HERS/Home Energy Rating System: HERS is an energy rating program used by homeowners, builders, and mortgage lenders to measure the energy quality within a home. HERS typically measures energy losing deficiencies.

HVAC home zoning: A home that is set up with zoning has separate thermostat controls for different areas, or zones, within the home. This allows certain areas to be cooler or more heated than others, which may lead to reduced energy use.

IAQ/Indoor air quality: IAQ refers to the amount of pollution that is in the air within a building.

Infiltration: Occurs when air leaks into a building from outside. Infiltration is usually present when there are cracks in the building structure.

Integrated heating system: An integrated heating system is a type of appliance that has the ability to perform multiple functions. A typical integrated heating system heats air as well as water for indoor plumbing use.

MERV rating: An acronym for Minimum Efficiency Reporting Value. MERV ratings are used to describe the size of the holes in filters. Filters with higher MERV ratings have smaller holes, which allow only the smallest sized particles to pass through.

Negative pressure: When more air is removed from a space than is given to the space, negative pressure occurs.

Particulates - Vapor retarder

Particulates: Particulates are minute particles of dust, fumes or other pollutants that contaminate inside air or that are released into outside air.

Plenum: The plenum is the section of ductwork that connects an air handler directly to the rest of the ducts in the system.

Positive pressure: When more air is pumped into a space than is removed to the space, positive pressure occurs.

Radiant barrier: A radiant barrier prevents heat from entering into a building, usually from the roof structure. It is made from a thin, foil sheet and is usually installed in attics.

Refrigerant: Also known as coolant, refrigerant is a liquid that is used in HVAC systems that aids in the transfer or removal of heat.

Return duct: Indoor air that is reused to heat or cool a building is supplied through the return duct.

R-value: A measure of a material's ability to withstand heat conductivity. Materials with high R-Values offer stronger resistance, thereby offering greater insulation from temperature changes, while materials with low R-Values have poorer resistance to heat.

SEER: An acronym for Seasonal Energy Efficiency Ratio. SEER is a term commonly used by HVAC professionals in order to rate the efficiency of an HVAC system.

A SEER rating described the amount of energy that is used to regulate temperature over the course of a year. Currently, the lowest SEER Rating allowed by the U.S. Department of Energy is 13.0.

Supply duct: Supply ducts are used with forced air systems. Forced air units function by pushing either heated or cooled air indoors through the supply ducts.

Therm: A unit of heat. One therm of air is equal to 100,000 BTUs.

Ton: A ton is a unit of measurement that is used when determining the amount of energy needed to cool indoor air. One ton of air is equal to 12,000 BTUs.

Vapor retarder: A vapor retarder is a type of material that hinders structural damage from moisture by blocking water vapor. This material is usually made from plastic sheeting, specially treated paper, low permeance paint or metallic foils.


Are there any recommendations for heating oil deliveries in the Glenside, PA area?

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