Nevada C-1A Boilers Contractor Examination

What is the primary purpose of a safety or pressure-relief valve on a boiler?

• AMaintain a constant circulating-loop temperature during light load.
• BAutomatically add makeup water when the system cools.
• CIndicate water level in the gauge glass during firing.
• DPrevent pressure from exceeding the boiler maximum allowable working pressure.

Which installation practice is prohibited on a boiler safety or relief valve?

• AA full-size discharge pipe of the same diameter as the valve outlet.
• BA rigid discharge pipe approved for the system temperature.
• CA shutoff valve between the boiler tapping and the relief valve, or on the discharge pipe.
• DSupport of the discharge pipe so it does not stress the valve body.

A suspected natural-gas leak at a boiler gas train should be located with which method?

• AAn open flame passed along fittings until the leak lights.
• BA listed combustible-gas detector or a noncorrosive leak-detection solution (soap test).
• COxygen introduced into the piping to raise the test pressure quickly.
• DA match at the relief-valve discharge to confirm draft.

Per UMC 2018 Section 1005.0, how must a boiler safety or relief valve discharge be piped?

• AReduced one pipe size, valved, and tied into the building sanitary stack.
• BThrough a water-seal trap so steam cannot enter the room.
• CInto the expansion tank so discharged water is saved.
• DFull size, with no valves or obstructions, to a safe point such as within 18 inches of th…

Using the indoor standard method, what minimum room volume is required for combustion air for a 120,000 Btu/h gas boiler?

• A1,200 cubic feet
• B2,400 cubic feet
• C6,000 cubic feet
• D12,000 cubic feet

What does a low-water fuel cutoff do on an automatically fired steam or hot-water boiler?

• AIt raises firing rate when the water line is low so remaining water boils faster.
• BIt automatically stops the burner when the water level falls below the lowest safe level.
• CIt opens the safety valve whenever the gauge glass is empty.
• DIt equalizes pressure between the supply and return headers.

Incomplete combustion at a gas- or oil-fired boiler is most dangerous because it can produce which product?

• APure nitrogen with no heating value.
• BDistilled water that floods the condensate trap.
• CInert argon that dilutes the flame to yellow.
• DCarbon monoxide, a toxic, odorless gas.

Before a light-off attempt on an NFPA 85 single-burner boiler, the furnace must be purged with about how many air changes?

• AOne air change at any damper position.
• BEight air changes of the furnace and gas-pass volume.
• CTwenty-four air changes with the fuel valves open.
• DNo purge is required if the last shutdown was less than one hour ago.

A hot-water heating boiler has a maximum output of 250,000 Btu/h. What is the minimum relieving capacity of its ASME pressure-relief valve?

• A250,000 Btu/h, at least equal to the boiler maximum output.
• B150,000 Btu/h, because 60 percent of output is enough.
• C30 psi, which automatically equals 30,000 Btu/h.
• DThe same gpm as the circulator nameplate.

A 180,000 Btu/h boiler takes all combustion air from outdoors through two vertical ducts. Metal louvers provide 75 percent free area. What minimum gross area is required for each opening?

• A18 square inches
• B45 square inches
• C60 square inches
• D180 square inches

Which reference listed for the Nevada C-1A exam governs installation of oil-burning equipment, tanks, and oil piping?

• ANFPA 54, National Fuel Gas Code
• BNFPA 70, National Electrical Code
• CNFPA 13, Standard for the Installation of Sprinkler Systems
• DNFPA 31, Standard for the Installation of Oil-Burning Equipment

Which fuel-oil grade is the usual distillate for automatic gun-type boiler burners?

• ANo. 6 residual (bunker) oil that must be heated to pump.
• BNo. 2 distillate fuel oil.
• CGasoline stored in the same indoor tank.
• DCrude oil taken directly from a well tank.

Per NFPA 31, where must a fuel-oil fill pipe terminate?

• AInside the boiler room within 12 inches of the burner.
• BInto the sanitary building drain through a trap.
• CAt the chimney cleanout so spills evaporate up the flue.
• DOutside the building at least 2 feet from any building opening at the same or lower level.

Per NFPA 31 8.6.3, a tank vent pipe shall terminate outside the building at a point not less than how far from any building opening?

• A6 inches measured along the wall only
• B2 feet measured vertically or horizontally
• C12 feet above the ridge in all cases
• D25 feet from the lot line in all cases

The outer end of a fuel-oil fill pipe must be equipped with which device?

• AA glass sight gauge that drains into the boiler room.
• BA tight metal cover designed to discourage tampering and identified as a fuel-oil fill.
• CA spring-loaded vacuum breaker open to the boiler room.
• DA hose-thread connection left uncapped for the next delivery.

Per NFPA 31 8.2.1, which materials are acceptable for tank fill and vent piping?

• APVC schedule 40 drainage pipe.
• BFlexible vinyl garden hose.
• CUnlisted polyethylene irrigation tubing.
• DWrought-iron, steel, or Schedule 40 brass pipe.

Unless an exception applies, oil piping that connects a burner to its supply shall not be smaller than which size?

• A3/8-inch iron pipe or 3/8-inch OD tubing
• B1/8-inch iron pipe or 1/8-inch OD tubing
• C1-inch iron pipe in all cases
• D2-inch iron pipe in all cases

Which fitting type shall not be used in fuel-oil piping under NFPA 31 8.2.5.4?

• AStandard steel pipe fittings.
• BListed copper-tubing fittings.
• CCast-iron fittings.
• DWrought-iron pipe fittings.

NFPA 31 8.2.10 prohibits transferring fuel oil to an appliance by which method?

• AA listed oil pump drawing from the tank.
• BGravity feed from an elevated tank through a listed constant-level valve.
• CPressurizing the storage tank with air or other gas.
• DA two-pipe suction and return loop into the top of the tank.

Unless the appliance is approved for a higher inlet pressure, the oil-supply pressure at the burner shall not exceed which value?

• A3 psig
• B15 psig
• C30 psig
• D100 psig

Where the supply tank is below the burner, how shall the oil piping be arranged?

• APitched toward the tank, with no traps in the line.
• BPitched toward the burner so oil always runs downhill to the nozzle.
• CInstalled with a water-seal trap at the lowest point.
• DLoop-sealed under the floor slab to keep air out.

A fuel-oil return line from a burner or pump to the supply tank shall be installed how?

• AWith a shutoff valve at the tank top and another at the burner.
• BTied into the tank vent so excess oil can breathe.
• CDischarged onto the boiler-room floor drain.
• DWith no valves or obstructions, entering the top of the same tank.

The vent outlet of a fuel-oil supply tank shall terminate at least how far from any air inlet or flue-gas outlet of an appliance?

• A6 inches
• B12 inches
• C5 feet
• D25 feet

After oil piping is installed and before it is concealed, NFPA 31 8.8.1 requires which tightness test?

• AA 10-minute soap test at 1 psig only.
• BA hydrostatic or pneumatic test at not less than 1-1/2 times maximum working pressure, bu…
• CAn oxygen pressure test at 25 psig for 24 hours.
• DNo test is required if flared copper fittings were used.

Two indoor fuel-oil supply tanks may be cross-connected to the same burner only if their aggregate capacity does not exceed which limit?

• A60 gallons
• B275 gallons
• C660 gallons
• D2,000 gallons

Which oil-tank gauging practice is prohibited by NFPA 31 8.7.4?

• AA method of determining oil level on tanks that do not keep a constant level.
• BA fill-point visual or audible signal that the oil has reached a predetermined safe level.
• CA glass gauge, or any gauge that will spill oil from the tank if the gauge breaks.
• DA listed liquid-level indicator arranged so oil or vapor is not discharged into the build…

Which PSI-allowed reference is the National Fuel Gas Code used on the Nevada C-1A exam?

• ANFPA 31, 2018 edition
• BNFPA 85, 2024 edition only
• CNFPA 58, 1998 edition
• DNFPA 54, 2012 edition

Per NFPA 54 (2012) 9.6.4, an appliance manual shutoff valve shall be located where?

• AOnly at the gas meter, regardless of appliance distance.
• BConcealed in a wall with no access panel.
• CWithin 6 feet of the appliance it serves, and accessible.
• DOn the vent connector, downstream of the draft hood.

Which medium shall never be used to pressure-test fuel-gas piping?

• AAir
• BNitrogen
• CCarbon dioxide
• DOxygen

What is the purpose of a sediment trap (drip leg) at a gas boiler?

• ATo raise manifold pressure to 2 psi.
• BTo replace the appliance manual shutoff valve.
• CTo vent flue gas if the chimney is blocked.
• DTo collect scale, dirt, and condensate before they enter the appliance controls.

Natural gas used in NFPA 54 pipe-sizing tables is assigned which specific gravity?

• A0.60 (lighter than air)
• B1.00 (same as air)
• C1.50 (typical LP-gas)
• D2.31 (same as feet of water per psi)

For a single-family dwelling gas-piping system, NFPA 54 (2012) 8.1.4 requires a pressure test of not less than 3 psi for at least how long?

• A10 minutes
• B1 minute
• C30 minutes in all cases, copied from NFPA 31
• D24 hours minimum on every house

What is the general minimum cover for underground fuel-gas piping under NFPA 54 (2012) 7.1.2.1?

• A6 inches in all locations
• B36 inches under every lawn
• C48 inches because Nevada frost line is assumed statewide
• D12 inches, increased to 18 inches where external damage is likely

Where must a gas sediment trap be installed when it is not built into the appliance?

• AUpstream of the meter only.
• BDownstream of the appliance shutoff valve, as close to the appliance inlet as practical.
• CIn the vent connector above the draft hood.
• DOn the hydronic return to catch magnetite.

A Category I gas-vent connector shall slope upward toward the chimney or vent at not less than which pitch?

• A1/8 inch per foot
• B1 inch per foot
• CLevel, to keep condensate in the connector
• D1/4 inch per foot

A Type B gas vent shall extend at least how far in vertical height above the highest connected appliance draft hood or flue collar?

• A12 inches
• B2 feet
• C5 feet
• D15 feet in every dwelling

A mechanical-draft gas vent terminating through a sidewall shall not terminate less than which clearance from a door, operable window, or gravity air inlet?

• A4 feet below or 4 feet horizontally from, or 1 foot above, the opening
• B1 inch from any opening in all directions
• C25 feet above finished grade only
• DNo clearance is required if the vent is plastic

Copper tubing used for fuel gas under NFPA 54 (2012) shall be which type?

• AType M only, because it is the thinnest and cheapest.
• BType DWV, because gas is not a water service.
• CType K or Type L.
• DAny refrigeration ACR coil regardless of listing.

A listed appliance fuel-gas connector shall not exceed which length?

• A3 feet
• B6 feet
• C15 feet
• D25 feet

When all combustion air comes from outdoors through two openings that communicate directly or through vertical ducts, each opening shall have a free area of not less than which ratio?

• A1 square inch per 1,000 Btu/h
• B1 square inch per 2,000 Btu/h
• C1 square inch per 3,000 Btu/h
• D1 square inch per 4,000 Btu/h

A 160,000 Btu/h gas boiler takes all combustion air from outdoors through two horizontal ducts. What minimum free area is required for each opening?

• A40 square inches
• B53 square inches
• C80 square inches
• D160 square inches

A 140,000 Btu/h atmospheric gas boiler is installed in a 30 ft × 20 ft × 8 ft room with no outdoor combustion-air openings. Using the indoor standard method, is the volume adequate?

• AYes. Required volume is 2,800 ft³ and the room has 4,800 ft³.
• BYes. Required volume is 1,400 ft³ and the room has 4,800 ft³.
• CNo. Required volume is 7,000 ft³ and the room has only 4,800 ft³.
• DNo. Required volume is 14,000 ft³ and the room has only 4,800 ft³.

In a closed hydronic heating system, what is the main job of the expansion tank?

• ATo add dissolved oxygen so the boiler water stays fresh.
• BTo raise static pressure to the relief-valve setting on every start.
• CTo store domestic hot water for kitchen use.
• DTo absorb the increase in water volume as the system is heated.

What is the function of a circulator in a forced-hot-water heating system?

• ATo create the combustion draft through the chimney.
• BTo move water through the boiler, piping, and heat emitters.
• CTo reduce gas manifold pressure to 3.5 inches water column.
• DTo open the safety valve at MAWP.

How does a hydronic convector typically deliver heat to a room?

• ABy boiling steam in an open pan on the floor.
• BBy heating a finned-tube element so room air moves across the fins by convection.
• CBy storing ice that is melted overnight.
• DBy dumping boiler flue gas into the occupied space.

One pound per square inch of water pressure is equal to approximately how many feet of water head?

• A0.433 feet
• B1.00 foot
• C2.31 feet
• D27.7 feet

Why are isolation (service) valves installed at a hydronic boiler and circulator?

• ATo replace the ASME pressure-relief valve.
• BTo keep the expansion tank from ever seeing system pressure.
• CTo block the relief-valve discharge as required by UMC 1005.0.
• DTo allow the boiler, pump, or a zone to be serviced without draining the entire system.