2024 Residential Mechanical Inspector

Residential Mechanical Inspector (M1)

60 Questions

2 Hours

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1. Which of the following materials is approved for use in a condensate disposal system?

A) Cross-linked polyethylene (PEX)

B) Lead

C) Black iron

D) Rigid aluminum

2 / 60

2. What is the maximum allowable pressure differential across the door of a mechanical room when return air is taken from it?

A) 0.10 inch wc

B) 0.05 inch wc

C) 0.01 inch wc

D) 0.02 inch wc

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3. What is the minimum vertical termination height above the highest connected appliance draft hood outlet or flue collar for a single-wall metal pipe?

A) 3 feet

B) 12 feet

C) 10 feet

D) 5 feet

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4. Zero lateral length applies only when the vent is:

A) Connected horizontally

B) A straight vertical vent attached to a top outlet

C) Connected to two appliances

D) Installed with at least two elbows

5 / 60

5. When a combustion air duct terminates in an attic space, which of the following is true?

A) It must be installed with insulation

B) It shall not be screened

C) It must be screened to prevent debris entry

D) It must include a backdraft damper

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6. Where is air not permitted to be discharged from a mechanical exhaust system?

A) Through a roof termination

B) Through a dedicated vent cap

C) Through an exterior wall

D) Into an attic or crawl space

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7. If not specified by the manufacturer, how far must a dryer exhaust duct terminate from openings into the building?

A) At least 18 inches

B) At least 6 feet

C) At least 3 feet

D) At least 12 inches

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8. Which pipe joint method is permitted for Schedule 40 or heavier pipe?

A) Glue joint

B) Compression only

C) Slip joint

D) Threaded, flanged, brazed, welded or listed press‑connect

9 / 60

9. What is the minimum required open area for a dryer exhaust duct terminal outlet passageway?

A) 15.0 square inches

B) 10.5 square inches

C) 18.0 square inches

D) 12.5 square inches

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10. According to the requirements, what should the pressure relief valve on a boiler be set to?

A) The minimum pressure level of the system

B) The normal operating pressure of the system

C) 50% above the boiler’s operating pressure

D) The maximum rating of the boiler

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11. What is the maximum allowed length for a 7-inch diameter smooth-wall exhaust duct for ventilation equipment with a fan rated at 250 CFM?

A) 133 feet

B) 148 feet

C) 88 feet

D) 54 feet

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12. Which of the following workmanship requirements must be met during gas piping installation?

A) Visible defects may be repaired on site.

B) Pipe and fittings must be free of burrs and defects.

C) Threaded joints may be reused.

D) Pipe must be painted yellow before testing.

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13. What is the requirement for the location of appliances to ensure proper air supply?

A) They must be installed in an attic

B) They must be placed near return air ducts

C) They must not interfere with circulation of combustion, ventilation, and dilution air

D) They must be installed next to exhaust equipment

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14. Plastic pipe venting materials listed to UL 1738 must be installed according to which of the following?

A) The builder’s written design

B) The vent manufacturer’s instructions

C) Standard IRC duct installation guidelines

D) The local utility provider's specifications

15 / 60

15. Are new under-floor plenums permitted in residential construction?

A) No, they are prohibited in new structures

B) Yes, if located in vented crawl spaces

C) Yes, if cleanouts are not present

D) Yes, with moisture barriers and sealed space

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16. What is the required minimum melting point of brazing material for nonferrous pipe joints?

A) >1000°F

B) 1200°F

C) 950°F

D) 750°F

17 / 60

17. When a single-wall metal pipe connector for an oil-fired appliance passes through a wall, what is required for protection?

A) A 2-inch clearance and plastic thimble

B) No protection if the pipe is under 4 inches in diameter

C) Installation inside a 2-hour fire-rated chase

D) A ventilated metal thimble 4 inches larger in diameter, with 6 inches clearance to combustibles

18 / 60

18. According to the IRC, combustion air ducts may serve:

A) A single enclosure only

B) Multiple enclosures if the appliances have the same input rating

C) Any space within the thermal envelope

D) Both upper and lower openings in the same system

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19. Which of the following standards must packaged oil-fired boilers conform to?

A) UL 834

B) ASME Boiler and Pressure Vessel Code, Section I

C) UL 2523

D) UL 726

20 / 60

20. Plastic piping used in undiluted LP‑gas systems must comply with which standard?

A) ASTM D2513

B) UL 467

C) CSA B149.1

D) NFPA 58

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21. Where must a draft hood be located in relation to combustion air openings?

A) In the attic space above the appliance

B) In a separate ventilated enclosure

C) Adjacent to the flue termination point

D) In the same room or space

22 / 60

22. Draft regulators are required for which of the following appliances when connected to a chimney?

A) Oil-fired appliances

B) Gas-fired appliances

C) Direct-vent appliances

D) Electric appliances

23 / 60

23. If not elevated, how far must an exhaust opening be located from a mechanical air intake?

A) 8 feet

B) 5 feet

C) 3 feet

D) 10 feet

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24. What is the required galvanized sheet metal thickness for a rectangular duct measuring 11 to 12 inches at 1/2-inch water gauge?

A) 0.019 inches

B) 0.016 inches

C) 0.024 inches

D) 0.013 inches

25 / 60

25. Which of the following is not an approved listing and labeling standard for refrigeration cooling equipment?

A) UL 484

B) UL 1995

C) UL 1042

D) UL/CSA 60335-2-40

26 / 60

26. Which of the following is not an allowed location for a vented floor furnace?

A) Where the burner assembly does not project into an occupied under-floor area

B) Where the register is 6 inches from an inside wall corner

C) Where the register is 5 feet below projecting combustible materials

D) Where the register is within 10 inches of a door

27 / 60

27. Where are shutoff valves required to be installed in relation to a heat exchanger in a hydronic piping system?

A) Only on the return side of the heat exchanger

B) On both the supply and return sides of the heat exchanger

C) Only on the supply side of the heat exchanger

D) No shutoff valves are required

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28. What is the minimum required vertical distance above finished ground level for an exterior combustion air intake opening?

A) 8 inches

B) 12 inches

C) 6 inches

D) 18 inches

29 / 60

29. How shall pressure regulators be vented according to G2421.3?

A) To the attic

B) To a plumbing vent

C) Directly outdoors

D) To a mechanical room

30 / 60

30. What is the minimum free area required for each combustion air opening when combining spaces on the same story?

A) 10 square inches per 1,000 Btu/h of appliance input

B) 2 square inches per 1,000 Btu/h of appliance input

C) ½ square inch per 1,000 Btu/h of appliance input

D) 1 square inch per 1,000 Btu/h of appliance input

31 / 60

31. What is the maximum horizontal hanger spacing allowed for copper or copper-alloy pipe in hydronic piping systems?

A) 8 feet

B) 12 feet

C) 10 feet

D) 6 feet

32 / 60

32. What is the requirement for conduit terminating outdoors in piping installations?

A) It must be sealed indoors only

B) It must be vented above grade and sealed

C) It must be painted yellow

D) It must terminate below grade

33 / 60

33. A dwelling with over 7,500 square feet and more than 7 bedrooms requires what minimum airflow for a continuous whole-house mechanical ventilation system?

A) 180 CFM

B) 135 CFM

C) 150 CFM

D) 165 CFM

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34. What is the minimum intermittent exhaust rate required for a bathroom or toilet room in a one- or two-family dwelling?

A) 40 CFM

B) 25 CFM

C) 20 CFM

D) 50 CFM

35 / 60

35. What is the minimum required width of solid flooring along the attic passageway to an appliance?

A) 24 inches

B) 22 inches

C) 30 inches

D) 18 inches

36 / 60

36. When installed on noncombustible flooring, how far must the floor extend beyond a vented room heater on all sides?

A) 18 inches

B) 12 inches

C) 16 inches

D) 24 inches

37 / 60

37. Before accepting a gas piping system for use what inspections must be completed?

A) Only pressure

B) Visual and pressure tests

C) Destructive weld testing

D) Only visual

38 / 60

38. What is the minimum thickness for a galvanized steel vent connector for a low-heat appliance with a diameter less than 6 inches?

A) 0.027 inch

B) 0.019 inch

C) 0.012 inch

D) 0.034 inch

39 / 60

39. Which of the following is considered part of the required indoor air volume for combustion air?

A) Attics connected by insulation baffles

B) Rooms directly connected to the appliance space by open, doorless passageways or code-sized combustion openings

C) Rooms connected by ductwork and vents

D) Rooms with openings that have doors and no vents

40 / 60

40. Protective steel shield plates must extend how far above sole plates to protect dryer exhaust ducts?

A) 1 inch

B) 1½ inches

C) 2 inches

D) 3 inches

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41. Which of the following materials is approved for use as a connector on oil or solid fuel-burning appliances?

A) Type L vent or single-wall metal pipe

B) PVC pipe

C) Corrugated aluminum duct

D) Cast iron

42 / 60

42. When sizing a vent for a high-altitude installation, what input rating should be used to determine the minimum capacity?

A) Sea-level input

B) Nameplate input

C) Derated actual input

D) Maximum hourly output

43 / 60

43. What must happen if a condensate pump located in an attic or crawl space fails?

A) The pump must automatically restart every 10 minutes

B) The appliance or equipment must be prevented from operating

C) A visual alarm must notify occupants

D) The equipment must continue to operate using a backup drain

44 / 60

44. Electric duct heaters must comply with which listing standard?

A) UL 1996

B) UL 484

C) UL 1995

D) UL 1042

45 / 60

45. When a chimney formerly used for liquid or solid fuel appliances is repurposed for gas appliances, the cleanout’s upper edge must be located how far below the lowest chimney inlet opening?

A) Not less than 3 inches

B) Not less than 6 inches

C) Not more than 12 inches

D) Exactly level with the lowest inlet

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46. What is required if the pressure drop results in supply pressure lower than the appliance minimum?

A) Lower the load.

B) Use larger appliances.

C) Install an isolation valve.

D) Redesign the piping system.

47 / 60

47. Which term in venting system tables indicates that a vent configuration is not permitted due to condensate risk or geometric limitations?

A) NAT Max.

B) FAN + FAN

C) NA

D) NAT + NAT

48 / 60

48. In what location are individual shutoff valves required for each boiler or modular boiler in multiple boiler installations?

A) Supply and return piping

B) Exhaust piping

C) Supply piping only

D) Return piping only

49 / 60

49. What is not permitted when working with load-bearing members of cold-formed steel light-frame construction?

A) Any cutting or notching of flanges and lips

B) Holes in the web section of steel framing

C) Use of screws or bolts for pipe support

D) Fastening piping within 1 inch of steel flanges

50 / 60

50. When is a sediment trap not required?

A) When incorporated in the appliance

B) If installed in horizontal runs

C) If installed outdoors

D) If gas type is dry

51 / 60

51. What must be included on the label of a fuel-burning unit?

A) Type of fuel, hourly rating in Btu/h (W), and required clearances

B) Voltage, amperage, and type of refrigerant

C) Fuel cost estimate and maintenance schedule

D) Manufacturer’s service hotline

52 / 60

52. When vents pass through insulated assemblies, what is the minimum required thickness of the steel used for the insulation shield?

A) 0.012 inch (No. 30 gage)

B) 0.034 inch (No. 20 gage)

C) 0.0187 inch (No. 26 gage)

D) 0.025 inch (No. 22 gage)

53 / 60

53. Which of the following statements about return air is correct?

A) Return air is permitted from bathrooms and closets if grilles are used

B) Return air may be shared between adjacent dwelling units if filtered

C) Return air from one dwelling unit shall not be discharged into another

D) Return air ducts must always terminate in the furnace plenum

54 / 60

54. Which of the following mounting practices is permitted for wall-mounted illuminating appliances?

A) Mounting to decorative fascia panels with gas pipe supports

B) Hanging from ceiling joists using galvanized plumber’s tape

C) Attaching directly to gas supply pipe with support straps

D) Secure mounting to structural surfaces without depending on gas piping

55 / 60

55. Installation of conversion burners must conform to which standard?

A) CSA B149.1

B) UL 1482

C) ANSI Z21.56

D) ANSI Z21.8

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56. What is the maximum horizontal length allowed for a Type B double-wall vent connector, unless part of an engineered system?

A) 75% of the height of the chimney or vent

B) 100% of the height of the chimney or vent

C) 50% of the height of the chimney or vent

D) 90% of the height of the chimney or vent

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57. What is the required number of threads to be cut on a 1-inch iron pipe according to table G2414.8.2?

A) 11

B) 8

C) 9

D) 10

58 / 60

58. What must fuel-fired appliances be designed for?

A) Conversion between fuels without restriction

B) Use with any available fuel source

C) Only natural gas at any altitude

D) The specific fuel type and installation altitude

59 / 60

59. For oil-fired or solid fuel-burning appliances, what is the minimum allowable connector size when connected to a natural draft chimney?

A) At least 1 inch larger than the flue collar

B) Based on total appliance input rating

C) Equal to or greater than the flue collar of the appliance

D) As required by the chimney manufacturer

60 / 60

60. Refrigeration systems using Group A1 refrigerants must be listed in accordance with:

A) UL 484 and UL 730

B) UL/CSA 60335-2-40 or UL 1995

C) UL 1996 only

D) ANSI Z21.47

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