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BOMI SMT practice questions

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Question 1Systems Maintenance Technician (SMT) designation curriculum

A building technician is asked to describe the primary purpose of a preventive maintenance program. Which statement best describes that purpose?

  1. Repairing equipment only after a breakdown has occurred
  2. Replacing all building equipment on a fixed annual cycle
  3. Scheduled servicing of equipment before failure to reduce breakdowns Correct answer.
  4. Documenting tenant complaints about building comfort

Explanation

Preventive maintenance means servicing, inspecting, and adjusting equipment on a planned schedule so that failures are avoided rather than repaired after the fact. It lowers unplanned downtime and extends equipment life. Complaint logging and blanket replacement are separate activities, not the definition of preventive maintenance.

Question 2Systems Maintenance Technician (SMT) designation curriculum

A technician must shut down a motor-driven pump to replace a worn coupling. Which step should be taken first to protect personnel?

  1. Notify the building owner of the repair cost
  2. Order the replacement coupling from the supplier
  3. Record the pump runtime hours in the log
  4. Verify zero energy state after lockout and tagout Correct answer.

Explanation

Lockout and tagout isolate the energy source, and the stored or residual energy must then be verified as zero before anyone works on the equipment. Only after verification is it safe to begin disassembly. Cost notification, parts ordering, and logging do not protect workers from unexpected energization.

Question 3Systems Maintenance Technician (SMT) designation curriculum

In a hot-water heating system, what is the function of an expansion tank?

  1. It filters sediment from the circulating water
  2. It absorbs the volume change of water as it is heated Correct answer.
  3. It raises the system pressure to the relief valve setting
  4. It stores hot water for domestic use

Explanation

Water expands as it warms, and the expansion tank provides an air cushion that accepts that added volume without over-pressurizing the loop. Without it, pressure swings would open the relief valve or stress the piping. It does not filter water, store domestic hot water, or set system pressure.

Question 4Systems Maintenance Technician (SMT) designation curriculum

A technician reads a refrigerant gauge set on a running air-conditioning system and wants to determine superheat. Which two measurements are required?

  1. Discharge pressure and liquid line temperature
  2. Suction pressure and suction line temperature Correct answer.
  3. Discharge pressure and compressor current
  4. Suction pressure and outdoor air temperature

Explanation

Superheat is the difference between the actual suction line temperature and the saturation temperature corresponding to the suction pressure. Both the suction pressure and the suction line temperature must therefore be measured at the same point. Discharge-side readings give subcooling, and ambient or electrical readings are not part of the superheat calculation.

Question 5Systems Maintenance Technician (SMT) designation curriculum

During a routine inspection a technician finds the condensate drain pan under an air-handling unit holding standing water. Which condition is the most likely direct cause?

  1. A loose belt on the exhaust fan
  2. A failed supply fan capacitor
  3. A clogged condensate drain trap or line Correct answer.
  4. An overcharged refrigerant circuit

Explanation

Standing water in a drain pan usually means condensate cannot leave, which points to a blocked trap, sloped or plugged drain line, or a dry trap that will not drain. Refrigerant charge, supply fan capacitors, and exhaust belts affect cooling or airflow but do not directly block condensate removal.

Question 6Systems Maintenance Technician (SMT) designation curriculum

A centrifugal chilled-water pump shows a worn mechanical seal and is leaking steadily. What is the correct maintenance response?

  1. Replace the mechanical seal and inspect the shaft for wear Correct answer.
  2. Tighten the gland until the leak stops permanently
  3. Add sealant to the chilled-water loop
  4. Increase the pump speed to compensate for the leak

Explanation

A leaking mechanical seal is a wear item and should be replaced, with the shaft and seal seat inspected for scoring or damage that would ruin a new seal. Speeding up the pump or adding chemicals treats symptoms and can damage the system. Gland tightening applies to packed pumps, not mechanical seals.

Question 7Systems Maintenance Technician (SMT) designation curriculum

A technician is troubleshooting a direct digital control loop where the valve does not respond to the controller output. Which check should come first?

  1. Recalibrate every sensor on the network
  2. Reconfigure the entire building automation schedule
  3. Confirm the controller output signal reaches the actuator Correct answer.
  4. Replace the controller with a new unit

Explanation

Effective troubleshooting moves from the controller output toward the field device, so the first check is whether the command signal actually arrives at the actuator. If the signal is present, the fault lies in the actuator or valve; if absent, the controller or wiring is suspect. Replacing hardware or recalibrating everything before this check wastes time.

Question 8Systems Maintenance Technician (SMT) designation curriculum

What is the purpose of balancing a hydronic distribution system after installation?

  1. To raise the loop pressure above the relief setting
  2. To adjust flow so each terminal receives its design water flow Correct answer.
  3. To increase pump horsepower to the maximum available
  4. To eliminate the need for control valves at terminals

Explanation

Balancing adjusts valves and flow devices so that every terminal gets the design flow rate, preventing short-circuiting of water to the nearest coils. Proper balance delivers intended comfort and efficiency. It does not raise pressure above relief settings, maximize pump power, or remove the need for control valves.

Question 9Systems Maintenance Technician (SMT) designation curriculum

A technician notices that a belt-driven supply fan squeals and the belt shows glazing and cracks. What is the appropriate action?

  1. Loosen the belt so it slips freely
  2. Increase the motor speed to stop the squeal
  3. Replace the belt and check pulley alignment and tension Correct answer.
  4. Apply belt dressing and continue operating

Explanation

Glazed, cracked belts are worn out and should be replaced, and the cause, usually misalignment or incorrect tension, must be corrected or the new belt will fail the same way. Belt dressing masks the symptom, and changing speed or deliberately loosening the belt accelerates wear and reduces airflow.

Question 10Systems Maintenance Technician (SMT) designation curriculum

Which practice best protects a cooling tower from biological growth and scale?

  1. Shutting off the fan during warm weather
  2. A documented water treatment program with regular testing Correct answer.
  3. Draining and refilling the basin once each year
  4. Adding untreated makeup water continuously

Explanation

Cooling towers require ongoing chemical or non-chemical treatment with regular testing of biocides, scale inhibitors, and blowdown control to limit biological growth, scaling, and corrosion. Annual draining alone does not control growth between cycles. Continuous untreated makeup and fan shutdown do not address water quality.

Question 11Systems Maintenance Technician (SMT) designation curriculum

A technician is inspecting a fire sprinkler system and finds a gauge reading zero on the wet system. What should be done?

  1. Assume the gauge is broken and take no action
  2. Open the main drain fully and leave it open
  3. Paint over the gauge to mark it as faulty
  4. Investigate for a closed valve, leak, or tripped condition and restore pressure Correct answer.

Explanation

Loss of pressure on a wet sprinkler system is a serious condition that can indicate a closed control valve, a leak, or a system trip, and it must be investigated and corrected promptly. Assuming the gauge is faulty or opening the drain would leave the system unprotected. Fire protection systems must remain charged and in service.

Question 12Systems Maintenance Technician (SMT) designation curriculum

What is the main function of a variable frequency drive on a supply fan motor?

  1. It replaces the need for a motor starter contactor
  2. It varies motor speed to match load and save energy Correct answer.
  3. It converts the motor to a single fixed speed
  4. It increases motor voltage above nameplate rating

Explanation

A variable frequency drive adjusts the frequency and voltage supplied to the motor so its speed can follow the actual load, which reduces energy use at part load. It does not fix speed, eliminate all starting components, or intentionally exceed nameplate voltage. Speed control is the defining function.

Question 13Systems Maintenance Technician (SMT) designation curriculum

A technician must verify that a newly installed motor rotates in the correct direction before coupling it to a pump. Which approach is appropriate?

  1. Wait for the pump to overheat as an indicator
  2. Bump-start the uncoupled motor and observe rotation Correct answer.
  3. Reverse two wires and assume rotation is correct
  4. Run the motor fully coupled and listen for noise

Explanation

The safe method is to momentarily bump-start the motor while it is uncoupled and observe the shaft direction against the required rotation arrow. Coupling first and relying on noise or overheating risks damage to the pump. Guessing at wiring changes without observation is not verification.

Question 14Systems Maintenance Technician (SMT) designation curriculum

Which task belongs to a routine monthly inspection of a centrifugal chiller rather than an annual overhaul?

  1. Disassembling the evaporator bundle
  2. Performing a full refrigerant recovery
  3. Replacing the compressor bearings
  4. Recording operating pressures and checking for leaks Correct answer.

Explanation

Routine inspections are non-invasive checks such as logging pressures, temperatures, oil levels, and looking for leaks or unusual noise. Bearing replacement, full refrigerant recovery, and bundle disassembly are major overhaul tasks performed on a longer cycle. Separating routine from overhaul work keeps maintenance planning accurate.

Question 15Systems Maintenance Technician (SMT) designation curriculum

A technician finds a steam trap that is blowing live steam continuously. What is the likely consequence if it is not repaired?

  1. Energy loss and possible water hammer or system imbalance Correct answer.
  2. Reduced steam pressure at the boiler only
  3. Automatic reset of the boiler safety controls
  4. Improved condensate removal and higher efficiency

Explanation

A trap stuck open passes live steam to the condensate return, wasting energy and upsetting the balance of the steam and condensate system, and it can contribute to water hammer. It does not improve efficiency, and it has no resetting effect on boiler safety controls. Failed traps should be tagged and repaired.

Question 16Systems Maintenance Technician (SMT) designation curriculum

Which reading indicates that a refrigerant circuit is likely undercharged?

  1. Low suction pressure with high superheat Correct answer.
  2. High discharge pressure with normal superheat
  3. High suction pressure with low superheat
  4. Normal suction pressure with normal subcooling

Explanation

When charge is low, less refrigerant enters the evaporator, so suction pressure drops and the vapor becomes more superheated before leaving the coil. High suction pressure with low superheat points instead to an overcharge or metering problem. Normal readings indicate a properly charged circuit.

Question 17Systems Maintenance Technician (SMT) designation curriculum

What is the purpose of a trap primer on a floor drain?

  1. It heats the drain line to prevent freezing
  2. It filters debris before it enters the drain
  3. It increases drain flow during heavy use
  4. It maintains a water seal in the trap to block sewer gas Correct answer.

Explanation

Floor drains in infrequently used areas can dry out, allowing sewer gas to enter the building, so a trap primer adds a small amount of water to keep the trap seal intact. It does not boost flow capacity, filter debris, or heat the line. Maintaining the seal is a health and odor control measure.

Question 18Systems Maintenance Technician (SMT) designation curriculum

A technician is replacing a failed pressure relief valve on a hot-water boiler. Which practice is correct?

  1. Add a shutoff valve below the relief valve for servicing
  2. Install a plug in place of the valve to stop weeping
  3. Install a valve with the same or approved rating and no shutoff valve downstream Correct answer.
  4. Set the new valve above the boiler's maximum allowable pressure

Explanation

Relief valves must match the boiler's rated capacity and pressure and must discharge without any downstream shutoff that could be closed and defeat the safety function. Plugging the opening or installing isolation below the valve removes protection. Setting the valve above the maximum allowable pressure defeats its purpose entirely.

Question 19Systems Maintenance Technician (SMT) designation curriculum

Which condition most commonly causes a centrifugal pump to cavitate?

  1. A worn coupling between motor and pump
  2. An oversized discharge pipe
  3. Excessive discharge valve opening
  4. Insufficient net positive suction head available Correct answer.

Explanation

Cavitation occurs when the absolute pressure at the pump suction falls below the liquid's vapor pressure, typically because available net positive suction head is too low. Symptoms include noise and vibration. Discharge valve position, coupling wear, and oversized discharge piping do not create the vapor bubbles that define cavitation.

Question 20Systems Maintenance Technician (SMT) designation curriculum

A technician is asked to set up a vibration monitoring route for critical rotating equipment. What is the main benefit of trended vibration data?

  1. Guaranteed reduction in equipment purchase costs
  2. Replacement of the need for operator inspections
  3. Elimination of the need for lubrication schedules
  4. Early detection of bearing wear and imbalance before failure Correct answer.

Explanation

Trending vibration lets a technician spot rising levels or changing signatures that indicate bearing wear, imbalance, or misalignment, so repairs can be planned before a breakdown. It does not remove lubrication or inspection duties, and it cannot guarantee procurement savings. It is a predictive maintenance tool.

Question 21Systems Maintenance Technician (SMT) designation curriculum

A technician notices that a pneumatic control system's actuator responds sluggishly and the compressor cycles frequently. Which area should be investigated?

  1. Air supply pressure and leaks in tubing and fittings Correct answer.
  2. The outdoor humidity sensor calibration
  3. The building's electrical demand profile
  4. Chilled-water supply temperature setpoint

Explanation

Pneumatic controls depend on a stable, dry air supply at the correct pressure; leaks or low pressure cause sluggish actuators and frequent compressor cycling. Water temperature, electrical demand, and humidity sensors do not explain compressed-air symptoms. Leak testing and pressure verification are the first steps.

Question 22Systems Maintenance Technician (SMT) designation curriculum

When a technician changes the air filter in an air-handling unit, why is it important to record the pressure drop across the new filter?

  1. It determines the building's ventilation code compliance
  2. It establishes a baseline for judging future loading Correct answer.
  3. It sets the unit's cooling capacity
  4. It proves the fan motor is correctly sized

Explanation

Recording the initial pressure drop gives a baseline, so later readings can show how much the filter has loaded and when it should be changed. It does not size the fan motor, set cooling capacity, or by itself establish code compliance. Baseline data supports condition-based maintenance decisions.

Question 23Systems Maintenance Technician (SMT) designation curriculum

What is the correct response when a technician finds frayed insulation on an energized electrical conductor inside a panel?

  1. Increase the breaker size to reduce heating
  2. Ignore it because the panel cover conceals the conductor
  3. De-energize the panel, then repair or replace the damaged conductor Correct answer.
  4. Wrap the frayed area with tape while the panel is live

Explanation

Damaged insulation on an energized conductor is a shock and arc-flash hazard, so the circuit must be de-energized before repair or replacement. Taping a live conductor exposes the worker to contact, ignoring it leaves a latent hazard, and upsizing a breaker does not fix insulation damage. Electrical work follows lockout and safe-work practices.

Question 24Systems Maintenance Technician (SMT) designation curriculum

A technician is evaluating why a rooftop unit short-cycles on its high-pressure switch on a hot afternoon. Which factor is the most probable cause?

  1. Restricted condenser airflow or a dirty condenser coil Correct answer.
  2. A clogged condensate drain
  3. An undercharged refrigerant circuit
  4. A failed evaporator fan motor

Explanation

High condensing pressure on a hot day usually results from poor heat rejection, such as a dirty coil, blocked airflow, or a failed condenser fan. An undercharge lowers pressure rather than raising it, and evaporator fan or drain problems do not directly cause high-side trips. Cleaning and airflow checks come first.

Question 25Systems Maintenance Technician (SMT) designation curriculum

Which document should a technician consult to confirm the correct lubricant and interval for a specific gearbox?

  1. The equipment purchase invoice
  2. A generic building maintenance checklist
  3. The manufacturer's installation and maintenance manual Correct answer.
  4. The building fire evacuation plan

Explanation

The manufacturer's manual specifies the approved lubricant type, quantity, and service interval for that exact model. Generic checklists may not match the equipment, and invoices or evacuation plans contain no lubrication guidance. Following the manual protects the warranty and the equipment.

Question 26Systems Maintenance Technician (SMT) designation curriculum

What is the primary purpose of a preventive maintenance program for building systems equipment?

  1. To eliminate the need for a maintenance budget
  2. To replace the need for operator training
  3. To guarantee that equipment never requires repair
  4. To reduce unplanned failures and extend equipment service life Correct answer.

Explanation

Preventive maintenance schedules routine tasks such as lubrication, inspection, and adjustment at planned intervals. Doing this work before failures occur reduces unexpected breakdowns, keeps efficiency high, and extends the useful life of equipment. It does not remove the need for budgets, training, or occasional repairs.

Question 27Systems Maintenance Technician (SMT) designation curriculum

A technician is about to service a pump driven by a motor controlled by a local disconnect. Which step must be completed before any work begins?

  1. Notify the building owner by email after work starts
  2. Close the discharge valve and start the pump briefly
  3. Lock out and tag out the disconnect and verify zero energy Correct answer.
  4. Remove the motor terminal cover while the circuit is live

Explanation

Lockout/tagout isolates the energy source and prevents accidental re-energization while a technician works on the equipment. Verification of zero energy, such as a voltage check at the motor terminals, confirms the isolation actually worked. This sequence protects the technician from shock and unexpected startup.

Question 28Systems Maintenance Technician (SMT) designation curriculum

Which unit is most commonly used to express the capacity of a cooling coil in North American building service work?

  1. Revolutions per minute
  2. Gallons per minute
  3. Pounds per square inch
  4. British thermal units per hour Correct answer.

Explanation

Cooling capacity describes the rate of heat removal, which is expressed in British thermal units per hour or in tons of refrigeration. Gallons per minute measures flow, pounds per square inch measures pressure, and revolutions per minute measures rotational speed. Only the heat rate unit describes coil capacity.

Question 29Systems Maintenance Technician (SMT) designation curriculum

What does a bearing temperature rise of 40 degrees Fahrenheit above ambient on a running motor most likely indicate?

  1. That the motor is oversized for the load
  2. A developing lubrication or alignment problem worth investigating Correct answer.
  3. That the ambient temperature sensor has failed
  4. Normal operation that requires no attention

Explanation

Bearings normally run warm but a rise well above ambient suggests friction from poor lubrication, misalignment, or excessive load. Trending the temperature helps confirm whether the condition is worsening. Investigating early prevents seizure and costly motor damage.

Question 30Systems Maintenance Technician (SMT) designation curriculum

Which practice best prevents scale buildup in a cooling tower basin?

  1. Adding fresh water only during winter months
  2. Increasing the recirculating water temperature
  3. Maintaining proper chemical treatment and blowdown control Correct answer.
  4. Reducing the makeup water supply pressure

Explanation

Scale forms when dissolved minerals concentrate as water evaporates, so chemical treatment and controlled blowdown keep mineral levels within limits. Blowdown removes concentrated water and makeup replaces it with fresher water. Temperature and supply pressure changes do not control mineral concentration.

Question 31Systems Maintenance Technician (SMT) designation curriculum

What is the main function of a strainer installed ahead of a control valve in a water line?

  1. To measure the flow rate through the valve
  2. To capture debris that could clog or damage the valve Correct answer.
  3. To regulate the downstream water pressure
  4. To absorb water hammer during valve closure

Explanation

A strainer protects downstream components by trapping dirt, scale, and debris before they reach the valve seat or plug. The screen must be cleaned periodically or it will restrict flow. Pressure regulation, flow measurement, and surge absorption are functions of other devices.

Question 32Systems Maintenance Technician (SMT) designation curriculum

A technician is asked to record a pump's suction and discharge pressures during a routine round. Why is this data useful?

  1. It establishes a baseline for detecting future performance loss Correct answer.
  2. It confirms the motor windings are electrically sound
  3. It replaces the need to measure flow directly
  4. It proves the pump is correctly sized for the building

Explanation

Recording pressures during normal operation creates a baseline against which future readings can be compared. A rising pressure differential or falling suction pressure can reveal fouling, wear, or cavitation before failure. The data supports trend analysis rather than proving design adequacy or electrical condition.

Question 33Systems Maintenance Technician (SMT) designation curriculum

Which item belongs on a technician's daily log for a central plant?

  1. The manufacturer's warranty expiration dates
  2. Operating pressures, temperatures, and any abnormal noises observed Correct answer.
  3. The building's construction drawings
  4. The original equipment purchase price

Explanation

Daily logs capture the current operating condition of equipment so trends and abnormalities can be spotted quickly. Pressures, temperatures, and unusual sounds are the kind of dynamic data that change day to day. Warranty dates, purchase prices, and construction drawings are reference documents, not daily operating records.

Question 34Systems Maintenance Technician (SMT) designation curriculum

A technician measures a voltage of 208 volts between two legs of a three-phase motor circuit. What does this reading most likely represent?

  1. The resistance of the motor windings
  2. The power factor of the motor
  3. The current drawn by one phase
  4. The line-to-line voltage supplied to the motor Correct answer.

Explanation

Voltage measured between two phase legs is the line-to-line supply voltage, which for many commercial systems is 208 volts. Current is measured in amperes, resistance in ohms, and power factor is a dimensionless ratio. The meter function and units identify the quantity being measured.

Question 35Systems Maintenance Technician (SMT) designation curriculum

A technician observes that a motor's running current is well above its nameplate full-load amps while the voltage is normal. Which cause is most likely?

  1. Mechanical overload or binding in the driven equipment Correct answer.
  2. A disconnected remote start contact
  3. An open winding in the motor
  4. A blown control fuse

Explanation

Excessive current with normal voltage points to the motor working harder than designed, often from a mechanical overload, misalignment, or binding load. An open winding, blown fuse, or open start contact would prevent the motor from running or draw no current. Current draw reflects the mechanical load placed on the motor.

Question 36Systems Maintenance Technician (SMT) designation curriculum

During a vibration survey, a technician finds that vibration amplitude rises sharply at exactly the blade-pass frequency of a fan. What does this pattern most likely suggest?

  1. A loose foundation bolt
  2. Misalignment between the motor and fan shaft
  3. Aerodynamic or blade-related imbalance such as a damaged or fouled blade Correct answer.
  4. A worn motor bearing

Explanation

Vibration concentrated at the blade-pass frequency typically points to problems with the fan wheel itself, such as a damaged, fouled, or unbalanced blade. Loose mounts, bearing wear, and shaft misalignment produce characteristic signatures at other frequencies. Matching the peak frequency to the component helps target the inspection.

Question 37Systems Maintenance Technician (SMT) designation curriculum

A technician must confirm that a newly installed motor rotates in the correct direction before coupling it to a pump. Which step is appropriate?

  1. Skip the check because the factory sets rotation direction
  2. Bump-start the uncoupled motor briefly and observe the shaft rotation Correct answer.
  3. Reverse two control wires at random until it sounds right
  4. Run the coupled pump for one hour and check for noise

Explanation

A brief bump start of the uncoupled motor lets the technician observe shaft rotation safely before the pump is connected. If rotation is wrong, swapping two of the three motor leads corrects it. Running the coupled pump in reverse can damage the pump and should be avoided.

Question 38Systems Maintenance Technician (SMT) designation curriculum

A technician finds that a steam coil is not heating even though steam pressure at the main is normal. Which check is most appropriate first?

  1. Verify the trap and control valve are functioning and condensate is draining Correct answer.
  2. Replace the coil immediately
  3. Close the main steam isolation valve
  4. Increase the boiler pressure setpoint

Explanation

Normal main pressure with poor heating usually means steam is not reaching or staying in the coil, often because the trap has failed or the control valve is stuck closed. Confirming condensate drainage and valve operation isolates the cause before any replacement. Raising boiler pressure or isolating the main does not diagnose the coil problem.

Question 39Systems Maintenance Technician (SMT) designation curriculum

What is the purpose of a bypass line around a control valve in a hydronic system?

  1. To reduce the pressure drop across the pump
  2. To increase the design flow rate through the coil
  3. To meter the amount of water used by the building
  4. To allow flow to continue while the valve is serviced or removed Correct answer.

Explanation

A bypass lets maintenance personnel isolate and remove a control valve while keeping water flowing through the circuit. This avoids a full system shutdown for repairs. It is not intended to change design flow, reduce pump pressure drop, or meter consumption.

Question 40Systems Maintenance Technician (SMT) designation curriculum

A technician is preparing to replace a compressor contactor. Which safety precaution is most important before starting the work?

  1. Wear gloves and work with the circuit energized to save time
  2. Remove the compressor from its mounting base
  3. De-energize and lock out the unit disconnect, then verify no voltage at the contactor Correct answer.
  4. Discharge the refrigerant charge to atmosphere

Explanation

Electrical work on a contactor requires the circuit to be de-energized, locked out, and verified dead before touching terminals. This protects against shock and arc flash. Working live, venting refrigerant, or unbolting the compressor are unnecessary and unsafe actions for a contactor replacement.

Question 41Systems Maintenance Technician (SMT) designation curriculum

A technician notices water dripping from the insulation on a chilled-water pipe in a conditioned space. What is the most likely cause?

  1. A failed vapor barrier or insulation that is too thin, allowing condensation Correct answer.
  2. Excessive water pressure in the pipe
  3. Too much glycol in the loop
  4. A closed valve downstream of the pipe

Explanation

Condensation forms when a cold surface is exposed to humid air and falls below the dew point. A damaged vapor barrier or inadequate insulation thickness allows moisture to condense on or inside the insulation. Water pressure, valve position, and glycol concentration do not directly cause surface condensation.

Question 42Systems Maintenance Technician (SMT) designation curriculum

A technician is asked to verify the operation of a low-water cutoff on a hot-water boiler. What is the correct approach?

  1. Disconnect the control and rely on the sight glass
  2. Drain the boiler completely and restart the burner
  3. Follow the manufacturer's test procedure and confirm the burner shuts off at the test level Correct answer.
  4. Increase the boiler setpoint and watch the gauge

Explanation

Low-water cutoffs must be tested using the manufacturer's procedure, which simulates a low-water condition and confirms the burner shuts down. Draining the boiler fully or bypassing the control defeats the safety function. The test verifies that the safety device actually works, not just that water is visible.

Question 43Systems Maintenance Technician (SMT) designation curriculum

A technician finds that a rooftop unit's condenser coil is heavily fouled with lint and dirt. What is the expected effect on system performance?

  1. Lower condensing pressure and reduced compressor current
  2. No measurable effect on capacity
  3. Lower discharge air temperature with no change in current
  4. Higher condensing pressure, higher compressor current, and reduced capacity Correct answer.

Explanation

A fouled condenser cannot reject heat efficiently, so condensing pressure and temperature rise. The compressor works harder, drawing more current and delivering less cooling capacity. Cleaning the coil restores heat transfer and reduces energy use.

Question 44Systems Maintenance Technician (SMT) designation curriculum

Which record is most useful to a technician diagnosing a recurring intermittent fault on an air handler?

  1. The original architectural floor plan
  2. The equipment history log showing past faults and repairs Correct answer.
  3. The building occupancy schedule
  4. The utility rate schedule

Explanation

An equipment history log records past faults, repairs, and parts replacements, which helps identify recurring patterns. Intermittent problems often leave a trail in service records that points to a root cause. Occupancy schedules, floor plans, and rate schedules do not document equipment behavior.

Question 45Systems Maintenance Technician (SMT) designation curriculum

A technician is setting up a new water-treatment program for a closed hot-water loop. Which parameter is most important to monitor to protect against corrosion?

  1. Return air temperature in the mechanical room
  2. Supply water pressure at the boiler
  3. Water flow velocity at the pump
  4. pH and inhibitor concentration Correct answer.

Explanation

Corrosion in closed loops is controlled by maintaining pH within the recommended range and keeping inhibitor concentration at target levels. These chemical parameters directly affect metal passivation. Flow velocity, boiler pressure, and room air temperature are not the primary corrosion indicators in a closed loop.

Question 46Systems Maintenance Technician (SMT) designation curriculum

A technician observes that a centrifugal chiller's approach temperature has increased gradually over several months while load and condenser water temperature remain similar. What does this trend most likely indicate?

  1. A refrigerant overcharge
  2. A failed compressor motor
  3. An open bypass valve in the chilled-water loop
  4. Fouling or reduced heat transfer in the condenser tubes Correct answer.

Explanation

Approach temperature is the difference between the leaving condenser water and the condensing refrigerant temperature. A rising approach at similar conditions indicates the condenser tubes are losing heat-transfer effectiveness, often from fouling. Overcharge, motor failure, and chilled-water bypass would not produce this specific trend.

Question 47Systems Maintenance Technician (SMT) designation curriculum

A technician must choose between repairing and replacing a 15-year-old packaged rooftop unit with a failed compressor. Which analysis best supports the decision?

  1. Defer the decision until the unit fails completely
  2. Choose replacement because the unit is more than ten years old
  3. Compare repair cost, remaining life, and energy cost against replacement cost and savings Correct answer.
  4. Choose repair because it always costs less than replacement

Explanation

A sound repair-versus-replace decision weighs the repair cost against the remaining service life, efficiency improvements, and future energy savings of a new unit. Age alone is not a sufficient criterion, and repair is not always cheaper over the life cycle. Deferring until total failure removes the chance to plan and budget.

Question 48Systems Maintenance Technician (SMT) designation curriculum

A technician finds a control valve that hunts continuously around its setpoint with a short cycle period. Which cause is most plausible?

  1. A closed isolation valve on the coil
  2. A failed temperature sensor reading high
  3. A clogged strainer upstream
  4. Excessive proportional gain or an oversized valve Correct answer.

Explanation

Hunting with a short period typically results from control loop tuning that is too aggressive or a valve oversized for the load, which makes small corrections produce large flow changes. A clogged strainer or closed isolation valve would reduce or stop flow rather than cause oscillation. Sensor failure usually produces a steady offset or a fixed reading.

Question 49Systems Maintenance Technician (SMT) designation curriculum

A technician is investigating repeated nuisance trips of a motor's overload relay. Which approach best identifies the root cause?

  1. Bypass the overload relay temporarily
  2. Increase the overload relay setting until trips stop
  3. Measure running current and compare it with the relay setting and nameplate data Correct answer.
  4. Replace the overload relay with a larger size

Explanation

Nuisance trips require comparing actual running current with the nameplate full-load amps and the relay's set point to see whether the trip is legitimate. If current is normal, the relay or its environment may be at fault; if current is high, the load or motor is the issue. Raising the setting, upsizing, or bypassing the relay removes protection without diagnosing the cause.

Question 50Systems Maintenance Technician (SMT) designation curriculum

A technician is planning maintenance on a cooling tower during a busy cooling season. Which consideration most affects the scheduling decision?

  1. The color of the tower basin
  2. The number of spare fan belts in stock
  3. The age of the maintenance vehicle
  4. The need to coordinate with building load and have backup capacity during shutdown Correct answer.

Explanation

Cooling tower maintenance often requires a shutdown, so scheduling must account for building cooling load and available backup capacity. Coordinating with building operations avoids comfort or process impacts. Basin color, vehicle age, and spare belt inventory are minor factors compared with system availability.