Free NATE CHP-5 Exam Flashcards

Verify that the equipment is isolated and de-energized before starting service. Address stored energy as part of the isolation procedure.

Check the product’s safety data sheet (SDS). It also gives guidance on protective equipment, storage, and accidental releases.

While climbing, keep either both hands and one foot or both feet and one hand on the ladder.

Reaming removes the ridge left by the cutter. Keep the shavings out of the tubing so debris cannot enter the refrigerant circuit.

A correctly sized bender helps preserve the tubing’s round cross-section. A kink reduces the flow area and can create a restriction.

Plan a route that preserves the truss. If it must be altered, obtain approval from a registered design professional and follow the locally adopted code.

In the evaporator. Low-pressure refrigerant absorbs heat as it boils, cooling the air that passes over the coil.

It regulates refrigerant flow into the evaporator and creates a pressure drop. The lower pressure lets the refrigerant boil at a temperature below that of the air being cooled.

EPA Section 608 technician certification is the federal credential for covered work. It is separate from NATE CHP-5. The required certification type depends on the equipment.

The damper closes in response to heat to help limit fire spread through the opening. Check the locally adopted code for the assembly and any exceptions.

3 A. Ohm’s law gives I = V ÷ R, so divide 24 V by 8 Ω.

Each branch connected across the same two points sees the same voltage. The branch currents depend on the individual loads.

It shows electrical paths between the supply rails. Follow the switches, safeties, and loads on those paths to work out the sequence of operation.

In a permanent split capacitor (PSC) motor, it stays in the auxiliary winding circuit and shifts that winding’s current phase relative to the main winding, helping produce a rotating magnetic field.

R is the transformer’s supply side and C is its common side on a typical single-transformer system. Confirm the terminals on the equipment wiring diagram.

The thermostat connects R to Y, sending a cooling demand to the equipment. The equipment’s controls and safeties determine when the compressor can run.

It confirms that the inducer has created the specified pressure differential. A failure to prove draft calls for diagnosis of the inducer, venting, and sensing path.

The control energizes a coil that moves the contacts. The contacts then complete the separate line-voltage circuit feeding the compressor.

Excessive resistance in the contact path, such as damaged contacts or a poor connection. Good closed contacts normally have very little voltage drop.

Compare the microfarad reading to the tolerance printed on the capacitor. Measure it only after isolating power, safely discharging it, verifying discharge, and disconnecting it from the circuit.

Relative humidity falls. The saturation vapor pressure rises as the air warms while the actual vapor pressure stays the same.

It brings in outdoor air and removes or dilutes contaminants that build up indoors. Recirculating air through a particle filter serves a different purpose.

Lower relative humidity. Wet-bulb depression is dry-bulb temperature minus wet-bulb temperature. Drier air allows more evaporation from the wet wick.

When the boot’s surface falls below the dew point of the surrounding air. That air becomes saturated as it cools at the surface.

Dry-bulb and wet-bulb temperatures. Their intersection lets you read properties such as humidity ratio, relative humidity, and dew point.

480 cfm. Multiply the duct cross-sectional area by the average air velocity. Here, 0.75 ft² × 640 ft/min = 480 ft³/min.

0.53 in. w.c. Subtract the signed return reading from the supply reading at the equipment manufacturer’s specified test points.

The filter is adding resistance, often because of loading. Compare the measured drop with the filter’s baseline or rating at that airflow.

Measure the airflow at each outlet and compare it with the design target for that room. Recheck other outlets after each adjustment because changing one branch can redistribute airflow.

Without an adequate return path, supply air pressurizes the room and can reduce delivered airflow. A properly sized return duct, transfer grille, or jump duct provides a way back.

Nitrogen displaces oxygen and limits oxide scale inside the tubing. Loose scale can contaminate the refrigerant circuit and restrict small passages.

The clearances allow airflow through the outdoor coil and help limit recirculation of discharge air. The installation instructions also specify room for service access.

It seals the unit-to-curb interface. A continuous gasket around the specified perimeter and duct openings helps prevent air leakage and water entry.

Negative pressure at the drain pan can pull air in through the drain and impede drainage. A water seal sized to the manufacturer’s instructions lets condensate leave while blocking that air path.

It measures absolute pressure at the system. Lower microns indicate a deeper vacuum. Use the equipment maker’s target and hold procedure to judge the result.

Compression and sharp bends increase resistance and reduce airflow. Use supports and spacing that keep the duct open and follow the manufacturer’s instructions.

The shallow diagonal bends stiffen the panel and reduce flexing as duct pressure changes.

Check the new unit’s requirements for tubing diameter, length and lift, refrigerant and oil compatibility, and line condition. Matching connection sizes alone is insufficient.

Airflow changes the load on the indoor coil and affects refrigerant readings. Establish the specified airflow, stabilize the equipment, and use the manufacturer’s charging method.

Confirm that the vent material, routing, and termination meet the furnace installation instructions and local code. Proper venting carries combustion gases outdoors.

52°F. Subtract return air temperature from supply air temperature after operation stabilizes. Compare the result with the furnace nameplate range.

15°F. Subtract saturated vapor temperature from measured suction-line temperature at the same location. Use the dew-point value for a blend with temperature glide.

12°F. Subtract actual liquid-line temperature from saturated liquid temperature at the same location. Use the bubble-point value for a blend with temperature glide.

It measures carbon monoxide in the combustion exhaust at the sampling point. A separate ambient measurement checks for CO in occupied air.

For a given fuel and a representative, undiluted sample, more residual oxygen generally indicates more excess air. Interpret the reading with CO and the appliance’s specified test conditions.

Verify that the indoor coil and metering device are approved for the new outdoor unit. Use the manufacturer’s match data to confirm compatibility and rated capacity.

A broad sheet-metal panel flexes and snaps as pressure changes. Inspect the panel and check for excessive system static pressure.

Measure delivered airflow and compare it with the room’s design target. Low flow points toward a local duct, damper, or return-path issue worth investigating.

75% of total cooling changes the air temperature and 25% removes moisture, under the measured or rated conditions. The ratio is sensible cooling divided by total cooling.

About 21,600 Btu/h. Multiply 1.08 × 800 cfm × 25°F. The 1.08 factor assumes standard air density and specific heat, so adjust it for substantially different conditions.