OR HVAC Contractor key terms

A credential issued by the state board that allows a business to offer or perform construction work, including HVAC installation, for compensation in Oregon. It requires a bond, insurance, and a qualifying individual who passes the required exam.

The person named on a contractor's license who has met the training and exam requirements and is responsible for the contractor's compliance with Oregon law. The license depends on this person's continued eligibility and good standing.

A surety bond a licensed Oregon contractor must keep in force to protect customers who suffer damages from the contractor's improper work or abandonment. A claim against the bond is filed through the state contractors board.

A written statement Oregon contractors must give residential customers, describing the right to file a complaint with the contractors board and to pursue the contractor's bond. It is typically required in the contract or as an attachment.

Oregon rules require a written contract for residential work above a set dollar threshold, signed by both parties and stating the scope, price, and payment terms. Change orders must also be documented in writing.

A legal claim recorded against real property by a contractor or supplier who was not paid for labor or materials that improved the property. Strict notice and deadline rules apply, and the lien can lead to foreclosure.

A written warning an Oregon contractor must give an owner at or before signing a contract, stating that unpaid contractors and suppliers may record a lien against the property. It protects the owner from surprise liens.

A notice a material supplier or subcontractor may give the owner early in a project to preserve lien rights even without a direct contract with the owner. Timing and delivery methods are set by statute.

A percentage of each progress payment an owner or general contractor withholds until the work is substantially complete. It provides leverage to finish punch-list items and resolve defects before final payment.

The stage when the work is sufficiently complete for the owner to use it for its intended purpose, even though minor items remain. It starts warranty periods and affects retainage and lien deadlines.

A written list of incomplete or defective items identified during a walkthrough near the end of a project. Completing the list is usually a condition of final payment and release of retainage.

The state board that licenses mechanical contractors and certifies HVAC and refrigeration technicians, sets continuing education rules, and administers discipline for code violations. It works alongside the building codes division.

The adopted statewide building code, based on the International Building Code with Oregon amendments, that governs structural, mechanical, and related construction requirements. Local governments enforce it with limited amendment authority.

Written authorization from a building department to install, alter, or replace regulated equipment. Work done without a permit can be ordered removed or exposed, and the contractor may face fines and license discipline.

A building official's on-site review of permitted work at defined stages to confirm code compliance. The installer must request it, and work must be accessible for review before it is concealed.

The last inspection that confirms all permitted work is complete and code compliant, allowing the system to be placed in service and the permit to be closed. It typically requires prior rough-in approvals.

The minimum distance required between heat-producing equipment, vent connectors, or flues and materials that can burn. Listed equipment labels state these distances, and reducing them without an approved method creates a fire hazard.

A listed double-wall metal vent for venting listed gas appliances with draft hoods. Its design maintains an insulating air space, allowing reduced clearance to combustible materials compared with single-wall pipe.

The pipe that carries flue gases from an appliance's draft hood or flue collar to the chimney or vent. Its size, slope, length, and rise are limited by code to ensure reliable draft.

A device on a gas appliance that mixes flue gases with room air and breaks excessive draft, stabilizing the pressure at the appliance outlet. It also prevents downdrafts from blowing out the pilot or burner flame.

A condition where combustion products spill from an appliance into the living space instead of rising up the vent, often because of depressurization, blockage, or a cold flue. It is a serious carbon monoxide hazard.

The air an appliance needs to burn fuel safely and to dilute flue gases. Codes specify how much must be supplied from indoors, outdoors, or a combination, and undersized supply causes incomplete combustion.

A colorless, odorless gas produced by incomplete combustion that binds to hemoglobin and can be fatal at low concentrations. HVAC work must prevent its generation and ensure it is vented outdoors.

A room-by-room method for estimating heating and cooling loads from building envelope, orientation, and climate data. Sizing equipment from it prevents short cycling and poor humidity control.

A method for sizing ducts and selecting fittings so that available static pressure matches the pressure drop through the distribution system. It uses room airflows from the load calculation.

A procedure for choosing equipment whose capacity matches the calculated load at the actual design conditions, including airflow and indoor wet-bulb. Oversizing is a common cause of comfort complaints.

The fraction of total cooling capacity that removes sensible heat, with the remainder removing latent heat. A high ratio means less moisture removal, so it helps diagnose humidity problems in a building.

The resistance to airflow measured at the supply and return plenums of an air handler, expressed in inches of water column. It indicates whether the duct system, filter, and coil are within the blower's rated capacity.

The volume of air moving through a system per unit time, commonly expressed in cubic feet per minute. Correct airflow is required for capacity, temperature rise, and safe heat exchanger operation.

The difference between supply and return air temperatures across a furnace or heat pump, checked against the manufacturer's rating plate range. An out-of-range rise signals airflow, fuel, or blower problems.

The number of degrees a refrigerant vapor is above its saturation temperature at a given pressure. It is used to verify the expansion device setting and to confirm the evaporator is properly fed.

The number of degrees a liquid refrigerant is below its saturation temperature at a given pressure. Measuring it helps confirm the condenser charge and the amount of liquid seal at the expansion device.

A thermostatic expansion valve that meters refrigerant into the evaporator while holding a target superheat. It responds to evaporator outlet temperature and pressure and is common in packaged and split systems.

The temperature at which a refrigerant changes phase at a given pressure. Comparing it with measured line temperatures is the basis for superheat and subcooling readings.

The process of removing refrigerant from a system into a recovery cylinder rather than venting it to the atmosphere. Federal rules prohibit knowing venting and require certified technicians and approved equipment.

The federal technician credential required to buy or handle regulated refrigerants and to service appliances containing them. It is issued after passing an EPA-approved exam covering environmental and safety rules.

A device that trips when current leaks from the circuit to ground, protecting people from shock. The electrical code requires it for receptacles serving equipment in certain wet or outdoor locations.

A fuse or circuit breaker that opens a circuit when current exceeds its rating, preventing conductor and equipment damage. HVAC equipment must be protected at or below the maximum rating on its nameplate.

A switch or breaker installed near equipment that removes all power for servicing. It must be within sight of the equipment and rated for the load, and its location must be clear to service personnel.

A control that senses space temperature and signals heating or cooling equipment to run. Modern programmable and communicating models add scheduling, humidity control, and fault reporting functions.

A small transformer that steps line voltage down to low voltage for thermostats, relays, and control boards. A shorted control circuit can overload and burn it out, causing a no-cooling call.

The ordered steps a system follows from a call for heat or cool through startup, normal running, and shutdown. Troubleshooters compare the observed sequence with the manufacturer's documented sequence to locate faults.

A required test of new or altered fuel gas piping using air or inert gas at a specified pressure for a set duration, with the system capped and isolated. Leaks are found with a bubble solution, never a flame.

A short downward leg of pipe installed before a gas appliance's controls to catch dirt, scale, and condensate. It protects the gas valve and orifices from debris carried in the supply line.

Another name for the sediment trap installed at the appliance connection, typically a tee with a capped nipple below the gas valve. It must be installed so debris settles out of the gas stream.

The practice of locating fuel gas leaks with an approved electronic detector or soap bubble solution applied to joints. Open flames are prohibited, and leaks must be repaired before the system is placed in service.

A procedure for de-energizing equipment, applying a personal lock and tag, and verifying zero energy before service. It prevents unexpected startup or release of stored energy such as refrigerant or gas pressure.

Gear such as gloves, safety glasses, and respirators worn to reduce injury risk on the job. HVAC work may require it for refrigerant contact, brazing, sharp edges, and electrical hazards.

An instrument that measures very low absolute pressure in microns to confirm a system has been evacuated of air and moisture before charging. A standing decay test shows whether the vacuum holds.

A tool with compound and high-pressure gauges plus hoses and valves used to read system pressures and to connect a recovery or vacuum pump. Proper purging prevents cross-contamination of refrigerants.