NJ HVAC Contractor key terms

The number of degrees a refrigerant vapor is above its saturation temperature at a given pressure. Measured at the evaporator outlet, it confirms the metering device is feeding the coil correctly.

The number of degrees a liquid refrigerant is below its saturation temperature at a given pressure. Measured at the condenser outlet, it verifies the charge and indicates how much liquid is stacked in the condenser.

A thermostatic expansion valve that meters refrigerant into the evaporator by holding a set superheat, using a sensing bulb on the suction line to modulate the orifice opening.

Heat energy absorbed or released during a phase change with no change in temperature, such as refrigerant boiling in an evaporator or steam condensing in a coil. It drives most of the cooling and heating capacity.

Heat that changes the temperature of a substance without changing its phase. It is what a thermometer reads and what dry-bulb temperature measures in air.

The total heat content of a substance per unit mass, combining sensible and latent energy. On a psychrometric chart, the difference in enthalpy between entering and leaving air gives coil capacity.

The temperature of air measured by a thermometer with a wetted bulb exposed to moving air, reflecting evaporative cooling. It indicates the moisture content and limits how cold evaporative or condenser-air cooling can go.

A graph plotting air properties, including dry-bulb, wet-bulb, dew point, humidity ratio, relative humidity, and enthalpy, used to calculate sensible and latent loads and coil performance.

The air supplied to a burner to support complete combustion. Codes require a permanent, adequately sized opening or duct from outdoors or a sufficiently large indoor volume for appliances in confined spaces.

Air mixed with fuel gas at the burner before ignition, which sets the initial flame shape and combustion quality. Excess primary air cools the flame; too little produces carbon monoxide and soot.

Air drawn into a draft hood or draft diverter to mix with flue products, stabilizing draft and diluting carbon monoxide. It is not combustion air, though codes often count it in vent sizing.

A device on a natural-draft gas appliance that isolates the burner from chimney pressure changes and admits dilution air. It must be installed in the same atmospheric pressure zone as the appliance it serves.

A gas appliance that operates with a non-positive vent pressure and a flue-gas temperature high enough to avoid condensation, vented with listed Type B vent or a lined masonry chimney.

A closed piping circuit that circulates heated or chilled water between a boiler or chiller and terminal units such as baseboard, radiators, or fan-coil units.

A tank connected to a hydronic system that absorbs the volume increase of water as it heats, limiting pressure rise and protecting the relief valve from nuisance discharge.

A pump that moves water through a hydronic loop, selected for flow rate and head pressure. It is typically sized to overcome pipe, fitting, and terminal-unit friction at design flow.

The outdoor temperature at which a heat pump's heating capacity equals the building's heat loss. Below it, supplemental or auxiliary heat must make up the difference.

Supplemental heating capacity, usually electric resistance strips or a second fuel-fired stage, that operates when a heat pump cannot meet the load alone or during defrost.

A timed or demand-initiated reversal of a heat pump's refrigerant flow that melts frost from the outdoor coil. It temporarily cools the space, so auxiliary heat is energised during the cycle.

The number of gallons of hot water a storage water heater can raise by a specified temperature rise in one hour. It depends on input rating, efficiency, and tank design.

The volume of hot water a storage water heater can deliver in the first hour of draw, accounting for tank volume plus recovery during that hour. It is used for sizing by fixture demand.

The sum of straight duct or pipe length plus the friction allowance assigned to fittings such as elbows and tees, expressed in feet. It is used to size fans, blowers, and pumps against total pressure loss.

The outward force per unit area exerted by air in a duct, measured in inches of water column. External static pressure is the resistance a blower must overcome through the duct system.

The pressure loss per unit length of duct, usually inches of water column per 100 feet of equivalent length. It drives duct sizing in the equal-friction method.

The route air travels from conditioned rooms back to the air handler, including return grilles, ducts, and the plenum. Undersized return paths raise static pressure and reduce delivered airflow.

A separate unit that conditions and delivers outdoor ventilation air to a building independently of the space heating and cooling equipment, often with its own dehumidification, leaving the terminal units to handle only the space load.

A room-by-room heating and cooling load calculation procedure that accounts for envelope, orientation, infiltration, and internal gains. In New Jersey it is the accepted basis for sizing residential equipment under the energy code.

A procedure for selecting equipment so its capacity matches the calculated Manual J load, including checking sensible and latent capacity at design conditions and verifying blower airflow.

A duct design procedure that sizes duct runs from the blower's available static pressure, the friction rate, and each run's equivalent length.

The outdoor and indoor temperatures and humidity values used for load calculations, taken from published weather data for the location. They set the capacity and airflow the system must deliver.

New Jersey's statewide building code, administered by the Department of Community Affairs, that adopts model codes and the associated licensing, permit, and inspection requirements for construction work.

The discipline-specific portion of the New Jersey construction code, such as building, electrical, plumbing, mechanical, or fire, each enforced by its own licensed subcode official.

A licensed municipal official who reviews and inspects work within a single technical section, such as mechanical or plumbing, and issues approvals for that discipline.

A New Jersey credential issued by the Board of Examiners of Heating, Ventilating, Air Conditioning and Refrigeration Contractors that authorises the holder to contract for and perform HVACR work.

The licensed individual whose credential qualifies a contracting business to operate and who is responsible for the work performed under that business's registration.

A permanent opening or duct sized by code to supply combustion, ventilation, and dilution air to fuel-burning appliances in a confined space. Blocking it is a common cause of carbon monoxide incidents.

The EPA credential required for technicians who service, repair, or dispose of appliances containing ozone-depleting refrigerants or their substitutes, obtained by passing a type-specific exam.

The process of removing refrigerant from a system into an approved container before opening or disposing of equipment, required by federal rules rather than venting it to the atmosphere.

A written amendment to a contract that modifies scope, price, or schedule after signing. Without a signed change order, extra work is often unenforceable and difficult to collect.

A legal claim against real property filed by a contractor or supplier who has not been paid for work or materials. New Jersey has strict notice and filing deadlines that must be met to preserve the right.