OR HVAC Contractor flashcards
OR HVAC Contractor · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- CCB license bond amount
- Oregon requires a $20,000 surety bond for a residential general contractor and $10,000 for a residential specialty contractor, filed with the CCB before the license is issued.
- Right to cure notice
- Before suing over a residential construction defect, the owner must give the contractor written notice and a reasonable chance to inspect and offer to repair.
- Oregon lien recording deadline
- A construction lien must be recorded within 75 days after the claimant last furnishes labor, materials, or equipment to the project.
- Written contract threshold
- Oregon residential contracts over $2,000 must be in writing and include the CCB number, scope of work, price, and payment schedule.
- CCB license renewal cycle
- Oregon contractor licenses renew every two years; renewal requires a current surety bond and completion of required continuing education hours.
- Oregon residential code scope
- The Oregon Residential Specialty Code applies to one- and two-family dwellings and townhouses, while commercial and larger multi-family work follows the Oregon Structural Specialty Code.
- HVAC rough-in inspection
- Rough-in inspection covers ductwork, refrigerant lines, gas piping, and venting before concealment; final inspection follows equipment startup and controls completion.
- Permit before HVAC work
- Installing, altering, or replacing HVAC equipment, ducts, or gas piping requires a permit from the jurisdiction before work begins.
- Combustion air opening sizing
- When both combustion air openings communicate with outdoors, each is sized at 1 square inch per 1,000 Btu/h of total appliance input.
- Sensible heat formula
- Sensible Btu/h equals 1.08 times CFM times the dry-bulb temperature difference across the coil or air handler.
- Latent heat formula
- Latent Btu/h equals 0.68 times CFM times the difference in humidity ratio measured in grains of moisture per pound of dry air.
- Manual J and Manual D
- ACCA Manual J calculates building heating and cooling loads; Manual D sizes the duct system to deliver that airflow at acceptable static pressure.
- External static pressure limit
- Total external static pressure equals supply plus return static; it must stay within the air handler's rated limit or airflow drops and the coil may freeze.
- Heat pump balance point
- The balance point is the outdoor temperature where heat pump capacity equals building heat loss; below it, supplemental heating stages operate.
- Superheat definition
- Superheat is the evaporator outlet temperature minus the saturated suction temperature at the measured suction pressure; typical target is 8 to 12 degrees F.
- Subcooling definition
- Subcooling is the saturated condensing temperature minus the liquid line temperature; typical target on a TXV system is 8 to 12 degrees F.
- TXV function
- A thermostatic expansion valve modulates refrigerant flow to hold a constant evaporator superheat as load and suction pressure change.
- Recovery cylinder fill limit
- A refrigerant recovery cylinder must not be filled above 80 percent of its capacity by weight, leaving room for liquid expansion.
- R-410A pressure behavior
- R-410A is a near-azeotropic HFC blend operating at roughly 60 percent higher pressure than R-22, so gauges and components must be rated for it.
- Suction accumulator purpose
- A suction accumulator traps liquid refrigerant and meters it back as vapor, protecting the compressor from liquid slugging on long or variable-load systems.
- Ohm's law and power
- Voltage equals current times resistance; power in watts equals voltage times current for a resistive load, with 746 watts per horsepower.
- Run capacitor failure signs
- A failed run capacitor reduces motor torque, raises running current, and causes the compressor or fan motor to overheat and trip overloads.
- Thermostat terminal letters
- R is 24-volt power, W is heat, Y is compressor, G is fan, O or B is the reversing valve, and C is common for thermostat power.
- Locked rotor amps
- LRA is the current drawn at startup with the rotor stalled; start capacitors and relays supply extra torque until the motor reaches running speed.
- Disconnect within sight
- The NEC requires a disconnecting means within sight of HVAC equipment and a branch circuit sized to the nameplate minimum circuit ampacity.
- Sediment trap location
- A sediment trap is installed downstream of the appliance shutoff valve and ahead of the gas controls to catch dirt and pipe scale.
- Vent category definitions
- Category I vents operate under negative pressure non-condensing, Category III positive pressure non-condensing, and Category IV positive pressure condensing.
- Manifold pressure check
- Natural gas appliances commonly require 3.5 in. w.c. manifold pressure and LP appliances 10 to 11 in. w.c., verified at the appliance regulator outlet.
- Gas piping leak test
- New gas piping is pressure-tested with air or inert gas at the code's specified test pressure and duration before gas is introduced.
- Nitrogen purge while brazing
- Flowing nitrogen through tubing during brazing prevents internal oxidation scale that can clog metering devices and contaminate compressor oil.
- A2L refrigerant handling
- A2L refrigerants are mildly flammable; service requires ignition-source control, ventilation, and leak detection per ASHRAE 15 and the equipment listing.
- Acetylene regulator limit
- Acetylene working pressure must never exceed 15 psig, and the torch valve should be opened no more than one and a half turns.