Iowa HVAC Exam Prep FREE Sample Exam — Fixed Set

A mountain-town home at 6,000 feet has high summer humidity during monsoon weeks and long mild shoulder seasons. Which equipment reasoning best fits all three conditions together?

Pick the largest single-stage unit available so altitude losses are covered by raw tonnage, accepting short shoulder-season cycles as a minor comfort tradeoff overall

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Size by nameplate sea-level capacity alone, because humidity control and part-load behavior matter far less at elevation than they do for lowland installations nearby

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Use derated capacity, favor modulation for part load and humidity control

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Choose equipment by its heating rating first and let cooling size fall where it may, since mountain homes are heating-dominated and summer loads rarely govern equipment selection

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A belt-drive blower motor draws nameplate amps at its current sheave setting. A proposal would raise blower speed by 10 percent to gain airflow. What should the contractor verify before approving the change?

Only that a longer belt is in stock, because a 10 percent speed change is small enough that motor loading can be assumed unchanged for planning purposes

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That the motor has reserve capacity, since power rises about 33 percent

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That the supply registers are adjustable, because register dampers alone can absorb any extra motor load created by the faster blower speed setting

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That the thermostat has a fan switch, because continuous fan operation is the only approved way to keep a faster blower motor within its temperature rating

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A furnace trips its rollout switch repeatedly. Flames are visibly rolling out of the burner compartment when the blower starts. Which cause should be investigated first?

A thermostat with a short cycle timer that repeatedly stops and restarts the furnace during a single call for heat, long before any flame or venting problem could develop in the burner compartment

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An oversized gas orifice in one burner

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Low gas supply pressure at the inlet tap

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A cracked or plugged heat exchanger, or blocked flue passage, that lets blower air or flue pressure push flames outward

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When a heating or cooling cycle ends and no zone is calling, many panels drive all zone dampers to the open position. Why?

To use the closed duct system as storage for conditioned air, holding the cooled or heated air in the branches until the next zone thermostat begins a call

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To test each damper motor at full travel after every cycle, because a damper that is not exercised to both stops on every cycle loses its panel calibration

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To raise static pressure in the idle system, which keeps dust from settling in the branches while the blower is off between equipment cycles

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So the next call, fan-only operation, or purge starts with an unrestricted air path

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A 24 V contactor coil measures 15 ohms. Using Ohm’s law, about how much current does the coil draw when energized?

0.63 A

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1.6 A

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39 A

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360 A

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A technician brazes a copper refrigerant joint and the filler metal balls up and refuses to flow into a properly cleaned joint. The flame was held mostly on the filler rod, heating the tubing unevenly. What technique correction is needed?

Add large amounts of additional flux all around the joint and keep applying it until the filler finally melts and flows into place on its own without further heating

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Quench the joint with water so the filler hardens faster

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Use a smaller flame and keep heating only the rod

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Heat the fitting and tubing evenly to proper brazing temperature and let the heated joint melt the filler, drawing it in by capillary action

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A large commercial restroom with a row of water closets needs a makeup-air path for its exhaust fan. Which arrangement works?

Seal the restroom completely — undercut, grille, and gaps all closed — so the exhaust fan can pull the room to its deepest possible vacuum, caulking every wall joint and fitting a sealed, gasketed door with a closer that pulls it fully shut against the frame

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Vent the exhaust fan into the corridor ceiling so the corridor, rather than the restroom, receives the odors being removed

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Provide transfer air — a door undercut, transfer grille, or ducted path sized so makeup air can enter as the fan exhausts, keeping the room slightly negative to contain odors

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Supply the restroom with more air than the fan exhausts so odors are pushed out into the corridor whenever the door is opened

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In proportional balancing, a branch reads 60 percent of design flow while the main reads 90 percent of design. What does proportional method direct the balancer to do first?

Close the main damper until the main also reads 60 percent so everything matches

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Set the branch reading 60 percent to exactly 100 percent of its design flow by opening its damper fully and leaving it there, regardless of how short the total system flow is or what happens to every other branch

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Work with the ratios: set the outlets in proportion to each other starting from the least-favored run, rather than forcing any single outlet to full design flow while the total is short

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Abandon the job, because any branch below design means the fan must be replaced

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A new 3-ton system is commissioned and total external static pressure measures well above the blower table limit at the selected tap, while delivered airflow is low. What is the correct commissioning response?

Add refrigerant until the temperature split looks normal despite the low airflow, adding charge in repeated increments and rechecking the split after each addition until it appears acceptable at the registers

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Raise the cooling charge target to compensate for the duct system

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Find and correct the restriction, such as undersized or crushed duct, a restrictive filter, or closed registers, then re-measure static and airflow

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Seal the return grille partly so static pressure numbers come down

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A stacked closet in a multifamily unit houses a water heater below and an air handler above, with barely enough room to remove the air handler’s filter. Why is this arrangement a service concern worth documenting?

Because stacked equipment voids the water heater warranty automatically, and documentation is needed only to assign warranty responsibility later

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Because filters in stacked closets never need changing, so the concern is limited to the appearance of the installation in inspection photographs

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Because water heaters in a shared closet heat the return air so much that cooling capacity is lost, and documentation triggers a larger cooling unit

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Because inadequate access leads to skipped maintenance and unsafe workarounds, and filters, drains, and shutoffs must remain reachable for routine service

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A homeowner who lives in a single-family house that is her principal residence wants to replace a failed component on her own furnace herself. A neighbor insists state trade licensure bars her from doing any of this work. Who is right?

The homeowner may do the work, since the licensing chapter does not prohibit an owner from working on the owner's principal residence of this kind

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The neighbor is right, because every repair to a fuel-burning appliance in any dwelling must be performed by a licensed master or a person working under one

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The homeowner may do the work only after obtaining a specialty sublicense, which is the credential the state issues to owners for work on their own homes

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The neighbor is right unless the home is farm property, because the owner exemption in the licensing chapter is limited strictly to agricultural buildings and land

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A dryer exhaust layout uses two 90-degree elbows and one 45-degree elbow. Taking the general maximum equivalent length of 35 feet, reduced by 5 feet for each 90-degree elbow and 2.5 feet for each 45-degree elbow, what is the longest actual straight duct run this layout may use?

22.5 feet of straight duct, with the three elbows consuming 12.5 feet of the length allowance the exhaust system is permitted overall

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35.0 feet of straight duct, with elbow deductions applied only when the manufacturer's instructions for the dryer are unavailable to the installer

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27.5 feet of straight duct, with each of the three elbows charged at the gentler 45-degree rate since the duct turns gradually at each fitting

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47.5 feet of straight duct, with each elbow adding its deduction figure to the allowance in the same way a longer vent raises a chimney's capacity

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Iowa HVAC Exam Prep FREE Sample Exam — Fixed Set

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