Title: Unit 13 Glossary
Course: HAC 140 Weatherization > Section: HAC 140 Weatherization

Unit 13 Glossary

Terms

Term | Definitions
Ambient air | Outdoor or unconditioned air.
ASHRAE | American Society of Heating, Refrigerating, and Air-Conditioning Engineers. International technical society which develops standards for those concerned with refrigeration processes and the design ...
Base load | The energy used by electric or gas appliances in a home that is not used for space conditioning, thus not a seasonal load.
Blower | Used in reference to furnace blowers, also called squirrel cages. The blades should be cleaned for optimal performance.
Cad cell | A flame sensor composed of the chemical compound cadmium sulfide. Its purpose is to sense whether a flame is present during a burner cycle. If a flame is not detected, it activates a relay, which ...
Carbon dioxide (CO2) | One of two main products of complete combustion of a hydrocarbon. (The other is water vapor.)
Carbon monoxide (CO) | Carbon monoxide is a tasteless, odorless, colorless, and poisonous gas that is a by-product of incomplete combustion of fossil fuels. It is usually caused by a lack of air to support combustion or ...
Carbon monoxide content | A measure of the carbon monoxide level in the air.
Certification label | Metal plate fastened to the exterior of a mobile home, showing that it meets all construction requirements under the HUD Code.
Combustible gas leak detector | Device used for finding natural gas or propane leaks.
Combustion air | Air that chemically combines with a fuel during the combustion process to produce heat and flue gases, mainly carbon dioxide and water vapor.
Combustion efficiency | Percentage of fuel burned during combustion, also referred to as steady state efficiency.
Concentric flue | A double wall flue pipe allowing the supply of combustion air and the simultaneous evacuation of combustion gases.
Conditioned air | Air that has been heated, cooled, humidified, or dehumidified to maintain an interior space within the "comfort zone."
Data plate | Mobile home label permanently affixed to the home, usually in a bedroom closet, the electrical panel box cover, or kitchen cabinet, which contains the name and address of the manufacturer, serial ...
Digital probe thermometer | Device for testing temperature rise and fan operating temperatures.
Domestic hot water tank (DHWT) access door | Portal allowing access to the domestic hot water tank in a mobile home.
Downflow | Air flow configuration in a furnace where cool air is taken from above and discharged as warm air from the bottom.
Draft gauge | Device for testing chimney draft.
Fan-off temperature | The furnace combination fan and limit control FAN OFF setting lets the furnace blower continue to run for an interval after the furnace burner has turned off, but will shut the blower off after th ...
Fan-on temperature | When the designated warm temperature has been reached inside of the furnace warm air plenum chamber the FAN ON switch turns on the furnace blower to deliver warm air to the occupied space.
Flue gas | Gases arising from the combustion of fuels, mainly consisting of carbon dioxide. Fuel gas normally contains pollutants, such as carbon dioxide, nitrogen oxide, sulfur dioxide, and dust.
Ground vapor retarder | A material that impedes the passage of water vapor from the ground.
Heat exchanger | Furnace component that transfers the heat from the combustion gases to the surrounding air. Combustion gases travel from the burner through the heat exchanger and then out the flue in properly fun ...
Heat rise | The number of degrees of temperature increase that air is heated as it is blown over the heat exchanger. Heat rise is measured as supply temperature minus return temperature.
High limit | Safety feature that causes the burner to shut down if the factory-set maximum temperature in the supply plenum is reached (typically set at 200 degrees F).
HUD code | Standards and specifications applied to mobile home construction as set forth by the U.S. Department of Housing and Urban Development.
I-beam | A rolled or extruded metal beam having a cross section resembling an I.
Incidental repair | Repair necessary for the effective performance or preservation of weatherization materials. Such materials may include framing or limited roof repair, so attic insulation doesn’t get wet. It doe ...
Indoor air quality (IAQ) | The quality of indoor air relative to its acceptability for healthful human habitation. Assessing and ameliorating, when necessary, the quality of indoor air is a major concern of the weatherizati ...
Inspection mirror | A small round mirror on the end of a handle used for viewing inside an inaccessible cavity.
Jalousie windows | A type of window usually associated with mobile homes with two or more panes of glass that pivot on a horizontal axis.
Make-up air | Air supplied to a space to replace exhausted air.
Manual J | Load calculation that allows the user to properly size HVAC systems for single-family-detached homes, small multi-unit structures, condominiums, town houses, and manufactured homes.
Manufactured home | Transportable homes that are quick and cheap to build. Another name for mobile home.
Minimum ventilation requirements (MVR) | Lowest level of ventilation that will be acceptable to human occupants and that will minimize the potential for adverse health effects. This level may be measured using ASHRAE Standard 62.2.
Mobile home belly | Part of a mobile home that contains the insulation, duct system, and plumbing. It is enclosed by the sub- and finished floor, with a rodent barrier underneath.
Mobile Home Energy Audit (MHEA) | Mobile Home Energy Audit software used to evaluate mobile home energy usage and predict cost effective retrofit based on savings to investment ratio.
National Fire Protection Association (NFPA) | A U.S. organization charged with developing standards for fire prevention and suppression, including the National Electric Code.
Oak Ridge National Laboratory (ORNL) | Laboratory where the Mobile Home Energy Audit (MHEA) software was developed.
Oxygen content | A measure of the amount of oxygen in the air.
Rodent barrier | Guard used to keep rodents from entering a mobile home through the belly.
Roof jack | Chimney assembly that penetrates the roof and includes the flashing and chimney cap assemblies.
Savings-to-investment ratio (SIR) | A calculation that determines the cost-effectiveness of a weatherization measure by dividing the estimated savings over its lifetime by the cost. SIR is computed over the lifetimes of the retrofit ...
Sealed combustion | A heater that draws air for combustion from outdoors and has a sealed exhaust system.
Site-built home | Homes that are constructed entirely at the building site. These homes conform to all State, local, or regional codes where the house is located.
Smoke tester | Device to test the amount of smoke being produced by an oil burning furnace. High smoke means the fuel-to-air ratio is off, and combustion is less efficient than it should be.
Steady-state efficiency | The measurement of heat system balance in the on-cycle when heat into system equals heat out. Generally provided as a percentage of the maximum available heat generation capacity (100%) against th ...
Steel chassis | Supporting frame for the mobile home structure exclusive of the body or housing.
Temperature rise | The number of degrees of temperature increase that air is heated as it is blown over the heat exchanger. Heat rise is measured as supply temperature minus return temperature. See also heat rise.
Thermal boundary/thermal barrier | The continuous layer of building components, such as insulation, that retard conductive heat flow. See also thermal envelope.
Thermal break | A thermal break is an element of low thermal conductivity placed in an assembly to reduce or prevent the flow of thermal energy between conductive materials.
Thermal mass | A solid or liquid material that will absorb and store warmth and coolness until it is needed.
U-factor | U-factor is a measure of non-solar heat flow through all the components of a material, typically used in reference to windows. The lower the U-factor, the better the thermal performance. U-factor ...
U.S. Department of Housing and Urban Development (HUD) | United States government agency charged with rule-making and enforcement of the HUD Code.
Window film | Plastic films, coated with a metallic reflective surface, that are adhered to window glass to reflect solar heat gain.
Worst case CAZ testing | A safety test, performed by specific procedures, designed to assess the probability of backdrafting in the home.