Connecticut HVAC Exam Prep FREE Sample Exam — Fixed Set

An evaporator has heavy frost building on the coil, low suction pressure, a warm conditioned space, and weak airflow from the registers. Inspection finds a very dirty air filter restricting air through the coil. The cause is most likely:

An overcharge of refrigerant

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A condenser fan running backwards

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Low airflow across the evaporator, which drops coil temperature below freezing and builds frost that blocks airflow further

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A liquid-line restriction after the filter drier that starves the evaporator, raises superheat, and reduces cooling in the last circuits of the coil downstream

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A homeowner asks why the new R-454B air handler runs its blower for a while after a leak sensor trips, even though cooling has stopped. What is the correct explanation?

The blower is removing residual heat from the electric heat strips, a normal cool-down sequence that happens to coincide with the sensor alarm event

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The blower pressurizes the duct system so refrigerant vapor is forced back through the leak point into the coil, resealing the system temporarily

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The blower dilutes and disperses leaked refrigerant through the duct system so room concentration stays low

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The blower run is a fault in itself, because mitigation design requires the air handler to shut down every moving part the instant a sensor trips

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A TXV system in cooling mode has normal evaporator superheat, both pressures somewhat high, and subcooling of 24°F against a manufacturer target of 10°F. Cooling capacity is slightly reduced. What condition best fits these readings?

Overcharge, with excess liquid backing up in the condenser

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Undercharge, with the condenser only partly filled with liquid

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A restricted liquid-line filter drier starving the TXV

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Low indoor airflow across the evaporator coil

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At a furnace install, a flexible gas connector is routed through a hole in the furnace cabinet side to reach the gas valve. What is wrong with this?

Connectors must not pass through the cabinet

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Flexible connectors are prohibited on all furnaces, so the entire run from the meter must be flexible line without rigid pipe

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The connector is too visible for inspection, and routing it through the cabinet is preferred so it is hidden from view at all times

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Nothing is wrong, provided the hole is left sharp and unbushed so the connector is gripped tightly and cannot move in service

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A 96% AFUE furnace is installed in a basement. Its flue gases are relatively cool and the vent system is designed to operate under positive pressure with a condensate drain at the furnace. How should its venting be handled?

Vent it into an existing unlined masonry chimney with no corrosion-resistant liner, relying on the chimney's natural draft to carry the cool flue gases out

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Use a single-wall metal connector into a Type B vent shared with a water heater

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Vent it with the manufacturer-approved sealed plastic vent system and drain the condensate as directed

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Let it vent into the basement and rely on dilution air to carry products out

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Return ducts leak in a dusty attic and the house seems dustier with a slight negative pressure effect on a water heater. Why is return leakage especially concerning?

It only wastes a little cool air

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It pulls unfiltered attic air and contaminants into the system and can depressurize the home

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It improves indoor air quality

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It lowers humidity in all cases

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A heating system with an adjustable heat anticipator short-cycles and the room temperature swings widely. The anticipator is set well above the actual control-circuit current through the thermostat. What adjustment is indicated?

Set the anticipator to match the measured current of the device it switches

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Increase the anticipator setting even further above the measured current in order to lengthen the heating cycles and reduce the temperature swing

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Remove the anticipator so the thermostat senses only room air

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Replace the thermostat with one that has no heating contacts

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A furnace clocks at an input 20% above its rating plate after a gas-valve replacement. The most likely setup causes are:

Manifold pressure set too high or wrong-size orifices installed

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A vent connector one size larger than the minimum, because a larger vent increases draft and pulls extra gas through the burner orifices

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A sediment trap with a long capped leg, because the trap volume adds a reserve of gas that the meter counts as additional furnace input

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A thermostat set several degrees above room temperature, because a larger temperature difference makes the gas valve deliver more fuel per hour

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On a cold morning a water heater spills briefly at the draft hood for the first minute after firing, then establishes steady draft and spills no more. The flue is clear and zone pressure is near neutral. What best fits this pattern?

Cold flue with delayed draft

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A blocked flue, which characteristically spills only at startup and then clears itself completely once the burner has run for about a minute

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A cracked heat exchanger in the nearby furnace, which pushes flue gas out of the water heater hood only while both appliances start at the same time

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Excessive combustion-appliance zone depressurization, which is known to disappear on its own as soon as the burner warms regardless of exhaust operation

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A meter shows a capacitor in a de-energized unit still holding charge. What should the technician do before handling its terminals?

Touch both terminals together with bare fingers to drain off the stored charge as quickly as possible

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Safely discharge the capacitor through an appropriate resistor and verify zero volts

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Assume it drained because power is off

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Hit it with a screwdriver handle

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A homeowner finished a 400-square-foot addition served by the existing system and now wants a changeout. What design step is required before selecting equipment?

A new load calculation covering the enlarged conditioned space, rather than sizing from the original home alone

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No calculation, because additions under 500 square feet are absorbed by the safety factor built into every residential system

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Sizing by the addition's square footage at the same tons-per-square-foot ratio the original installer used decades ago

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Selecting equipment one full ton larger than the old unit, which reliably covers any addition of this general size

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A boiler room in a New Haven building contains fuel-fired appliances with a combined input of 160,000 Btu/h, and the contractor wants to rely on the indoor-air standard method for combustion air. The room as built measures 7,500 cubic feet. What does the method require here?

The room is unconfined, because the standard method needs only 25 cubic feet per 1,000 Btu/h, which gives 160 x 25 = 4,000 cubic feet for this combined input rating and plenty of margin.

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More room volume or another combustion-air method: the standard method needs 50 cubic feet per 1,000 Btu/h, so 160 x 50 = 8,000 cubic feet, and a 7,500-cubic-foot room leaves the space confined.

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The room is unconfined no matter what its volume is, because indoor air may always be used when the appliances sit in a room whose door can simply be left open during firing.

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The volume is sufficient if only the largest single appliance is counted instead of the combined input, because the indoor method is applied appliance by appliance in a shared room.

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Connecticut HVAC Exam Prep FREE Sample Exam — Fixed Set

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