Nevada C-1F Heating, Cooling and Circulating Air Contractor Examination

Per the 2018 UMC fuel-gas rules allowed on the Nevada C-1F exam, which test medium is prohibited when pressure-testing new gas piping?

• ADry air
• BNitrogen
• CCarbon dioxide
• DOxygen

After a fuel-gas piping system is pressurized, the accepted field method to locate a leak is which of the following?

• APass an open flame along each joint until the flame lengthens
• BStrike each fitting with a hammer and listen for a change in pitch
• COpen every appliance valve and smell for odorant at the burner
• DApply a noncorrosive leak-detection solution and watch for bubbles

Carbon monoxide from a gas-fired warm-air furnace is produced primarily by which condition?

• AComplete combustion with excess outdoor air
• BA high-limit switch that opens on a temperature rise
• CA listed Type B vent with the required 1 inch clearance
• DIncomplete combustion from a cracked heat exchanger, blocked vent, or starved burner

Before opening a gas train, replacing a circulating pump, or working on an electrically powered furnace blower, the C-1F mechanic's first safety step is to:

• AIncrease thermostat setpoint so residual heat is used up
• BBypass the high-limit so the unit cannot cycle during the repair
• COpen a window and leave the unit running so CO is diluted
• DLock out and tag the electrical disconnect and close the appliance fuel shutoff

Clearance from a listed warm-air furnace, unit heater, or vent connector to combustible construction is determined first by which source?

• AA uniform 18 inch rule for every gas appliance
• BThe C-1F license classification, which sets a 6 inch statewide clearance
• CWhatever clearance the existing building already provides
• DThe appliance or vent listing and the manufacturer's installation instructions, then the…

A Category I furnace is being started in a tight mechanical closet after weatherization sealed the building. The most important safety check before firing is that:

• AThe thermostat anticipator is set to 1.0 ampere
• BThe evaporator coil is charged to nameplate superheat
• CThe gas meter index is turning even with all appliance valves closed
• DRequired combustion air volume or outdoor openings are provided so the burner is not star…

When a new fuel-gas piping system is placed in service, residual air must be purged. The 2018 UMC / NFPA 54 practice is to discharge the purge:

• AInto the furnace heat exchanger so the inducer can dilute it
• BInto a return-air plenum so the blower mixes it below the lower explosive limit
• CThrough a lighted burner so any gas is immediately consumed
• DTo a safe outdoor location, away from ignition sources and openings into the building

A replacement gas furnace is installed in a residential garage. In addition to vehicle-protection and elevation rules, the unit must have which electrical safety feature at the appliance?

• AA lighting outlet only, with the disconnect at the electric meter
• BA GFCI receptacle in lieu of an equipment disconnect
• CA 30-amp fuse in the thermostat cable
• DA readily accessible disconnecting means in sight of the appliance, as required for the e…

A homeowner reports headaches whenever the furnace runs. The circulating air smells of exhaust, the flame wavers when the blower starts, and a CO detector near the supply register alarms. The most likely equipment failure is:

• AA dirty evaporator coil starving refrigerant flow
• BAn oversized Type B vent that is slightly cool
• CA clogged evaporative-cooler pad on the same roof
• DA cracked heat exchanger allowing flue gas into the circulating-air stream

A mechanical room houses a 100,000 Btu/h atmospheric furnace. A new 400 cfm kitchen exhaust is added with no makeup air. The principal combustion-air hazard is that the exhaust can:

• AIncrease indoor volume above the 50 cubic feet per 1,000 Btu/h threshold
• BRaise the furnace temperature rise and trip only the fan switch
• CConvert the furnace to a Category IV condensing appliance
• DDepressurize the room so the furnace backdrafts and spills flue gas at the draft hood

Per 2018 UMC Section 1316.9 as used on the Nevada C-1F open-book exam, a new low-pressure fuel-gas piping system (not welded, not more than 14 inches water column) shall stand an air, carbon dioxide, or nitrogen test of not less than which pressure and time?

• A3 psi for 10 minutes
• B60 psi for 30 minutes
• CWorking pressure only, held for 5 minutes
• D10 psi for not less than 15 minutes with no perceptible drop

Per 2018 UMC Section 1316.9, welded fuel-gas piping, or piping that will carry gas at pressures in excess of 14 inches water column, shall be tested at not less than which of the following?

• A10 psi for 15 minutes
• B15 psi for 15 minutes
• C25 psi for 10 minutes
• D60 psi for not less than 30 minutes

Where a sediment trap is not built into a gas appliance, the 2018 UMC requires the sediment trap to be installed in which location?

• AUpstream of the appliance shutoff valve, as close to the meter as practical
• BIn the street-side service riser below the meter
• COnly on propane systems; natural-gas furnaces do not need sediment traps
• DDownstream of the appliance shutoff valve, as close to the appliance inlet as practical

Per the 2018 UMC, each gas appliance shall have a shutoff valve located in the same room as the appliance and within what maximum distance of the appliance?

• A3 feet
• B10 feet
• C25 feet, if the valve is readily accessible
• D6 feet

Corrugated stainless steel tubing (CSST) gas piping installed under the 2018 UMC must be electrically bonded because:

• AA low-impedance bond to the structure grounding electrode system reduces arc damage if th…
• BBonding replaces the need for a sediment trap
• CCSST is listed only for propane and must be isolated from natural-gas steel pipe
• DBonding allows the installer to omit the appliance shutoff valve

A copper hydronic heating line is joined to a steel boiler tapping. The fitting used to limit galvanic corrosion at that joint is a:

• ADielectric union or dielectric isolating fitting
• BStandard black-iron coupling
• CFlare union rated only for fuel gas
• DRubber hose barb

Underground metallic fuel-gas piping installed under the 2018 UMC must be protected from corrosion by which method?

• AApproved coating or wrapping, with joints and fittings coated after assembly, or a listed…
• BPainting the pipe with leftover latex after backfill
• CLeaving bare steel because soil moisture equalizes potential
• DWrapping only the last 12 inches before the riser

A closed hydronic heating circuit delivers 100,000 Btu/h with a 20°F water temperature drop. Using GPM = Btu/h ÷ (500 × ΔT), the required flow is closest to:

• A5 gpm
• B8 gpm
• C10 gpm
• D20 gpm

Per 2018 UMC Section 701.4.1 (standard indoor method), the minimum indoor volume that may supply combustion air without outdoor openings is how many cubic feet per 1,000 Btu/h of appliance input?

• A20 cubic feet
• B35 cubic feet
• C50 cubic feet
• D100 cubic feet

Using the 2018 UMC Chapter 7 two-permanent-openings outdoor method, where the openings communicate directly with the outdoors or through vertical ducts, each opening shall have a free area of not less than:

• A1 square inch per 1,000 Btu/h of total input
• B1 square inch per 2,000 Btu/h of total input
• C1 square inch per 4,000 Btu/h of total input
• D1 square inch per 5,000 Btu/h of total input

Using the 2018 UMC Chapter 7 two-permanent-openings outdoor method, where the openings communicate with the outdoors through horizontal ducts, each opening shall have a free area of not less than:

• A1 square inch per 2,000 Btu/h of total input
• B1 square inch per 1,000 Btu/h of total input
• C1 square inch per 4,000 Btu/h of total input
• D1 square inch per 10,000 Btu/h of total input

When two permanent indoor openings connect a furnace closet to adjacent indoor volume, 2018 UMC Chapter 7 requires each opening to have a free area of not less than 1 square inch per 1,000 Btu/h and not less than:

• A50 square inches
• B75 square inches
• C100 square inches
• D200 square inches

Under the 2018 UMC Chapter 7 one-permanent-opening outdoor method, the single opening to the outdoors shall have a free area of not less than:

• A1 square inch per 1,000 Btu/h of total input
• B1 square inch per 2,000 Btu/h of total input
• C1 square inch per 3,000 Btu/h of total input, and not less than the sum of the vent-conne…
• D1 square inch per 8,000 Btu/h of total input

A 80,000 Btu/h Category I furnace is installed in a 20 ft × 20 ft × 8 ft room that does not communicate with other indoor space. Using the UMC 701.4.1 standard method, the room:

• AHas 3,200 cubic feet, which is less than the 4,000 cubic feet required (50 × 80), so outd…
• BHas 3,200 cubic feet, which exceeds the 4,000 cubic feet required, so no outdoor openings…
• CNeeds 8,000 cubic feet, so the furnace cannot be installed in any residential room
• DIs automatically unconfined because it is larger than a closet

Where two combustion-air openings serve an enclosure, 2018 UMC Chapter 7 locates them so that:

• AOne opening begins within 12 inches of the top of the enclosure and one within 12 inches…
• BBoth openings are centered on the door at mid-height
• CBoth openings are in the ceiling so hot flue gas can escape
• DBoth openings are in the floor so cold air cannot short-circuit

Combustion-air openings are covered with metal louvers that are not listed for a free-area percentage. 2018 UMC Chapter 7 assumes the metal louvers have a free area of:

• A25 percent of the louver face area
• B50 percent of the louver face area
• C75 percent of the louver face area
• D100 percent of the louver face area

Where mechanical combustion-air supply is used, 2018 UMC Chapter 7 requires the fan to interlock with the appliance and to deliver not less than which airflow per 1,000 Btu/h of total input?

• A0.35 cfm
• B0.10 cfm
• C1.00 cfm
• D4.00 cfm

A closed hydronic heating system rises 23.1 feet from the fill valve/gauge to the highest radiation. Using fill pressure = (height in feet ÷ 2.31) + 4 psi for positive venting, the cold-fill pressure should be set closest to:

• A8 psi
• B10 psi
• C14 psi
• D30 psi

On a closed, completely filled hydronic heating loop, the circulator's required total dynamic head is primarily the sum of:

• APipe, fitting, valve, and terminal friction losses around the circuit; static lift cancel…
• BThe building height in feet, because the pump must lift every gallon to the top floor
• CBoiler horsepower multiplied by 2.31
• DThe relief-valve setpoint in psi converted to feet

The connection of a diaphragm expansion tank, and therefore the hydronic point of no pressure change, should be located:

• AOn the system piping at the pump suction, typically near the air separator and fill valve
• BOn the pump discharge so the tank sees maximum pressure
• CAt the highest radiation so air can leave through the tank
• DOn the boiler drain so the tank can be emptied with the boiler

Per 2018 UMC Chapter 12, hydronic panel piping that will be embedded in building construction shall be hydrostatically tested at not less than which pressure before it is covered?

• A15 psi for 5 minutes
• B30 psi, equal to the relief-valve setting
• C100 psi
• DWorking pressure only, after the finish floor is installed

Fuel-gas pipe on the 2018 UMC C-1F exam is sized by the longest-length method. That method uses which length to enter the capacity table for every section of the system?

• AThe length of the shortest branch only
• BThe vertical rise only, ignoring horizontal run
• CThe developed length from the meter or regulator to the most remote appliance, used for a…
• DThe sum of all branch lengths added together as one equivalent pipe

Fuel-gas piping that passes through a concrete slab or underground exterior wall must be protected from damage and shear by:

• AA listed sleeve, wrapping, or other approved protection at the penetration
• BA tight concrete grout bond with no sleeve so the pipe cannot move
• CLeaving a 2 inch unsealed hole so the pipe can sweat
• DA hose clamp and duct tape at the slab edge

PEX tubing used as the closed-loop piping of a hydronic heating system should have which additional feature that potable-water PEX often lacks?

• AAn oxygen-diffusion barrier, so oxygen cannot enter the loop and corrode iron boilers and…
• BA fuel-gas listing so the same coil can carry natural gas
• CA refrigerant flare so the loop can be converted to a heat pump
• DNo markings, so the tubing can be buried unlisted

A hydronic coil must deliver 80,000 Btu/h with a 10°F water temperature drop. Using GPM = Btu/h ÷ (500 × ΔT), the required flow is:

• A8 gpm
• B10 gpm
• C16 gpm
• D32 gpm

In hydronic head calculations, 1 psi of water pressure is equal to which column of water?

• A1.00 foot
• B4.62 feet
• C2.31 feet
• D27.7 feet

A mechanical room contains a 120,000 Btu/h furnace and a 40,000 Btu/h water heater, total 160,000 Btu/h. Using the outdoor two-opening vertical/direct method (1 in² per 4,000 Btu/h), each opening requires a free area of:

• A20 square inches
• B32 square inches
• C40 square inches
• D160 square inches

A furnace closet has only 60 percent of the indoor volume required by UMC 701.4.1. The installer wants to use the combination indoor-and-outdoor combustion-air method. The correct approach is to:

• AIgnore the shortfall; 60 percent is close enough for Category I appliances
• BSize outdoor openings for the full input, then also add the full indoor openings
• CReduce the outdoor opening sizes in proportion to the indoor volume that is actually avai…
• DSeal the closet completely and rely on the draft hood to pull air down the vent

Automatic makeup water to a closed hydronic heating system must be protected against backflow into the potable supply by which device?

• AA listed backflow preventer or approved air gap on the makeup line, plus a pressure-reduc…
• BA boiler drain hose left in a mop sink
• CA gas cock on the cold-water line
• DThe expansion tank alone, which isolates the city main

The 2018 UMC prohibits installing fuel-gas piping in which of the following locations?

• AA dedicated, ventilated mechanical room
• BA crawl space with the pipe supported and protected
• CAn air duct, clothes chute, chimney, or elevator shaft, or a circulating-air plenum
• DAn exterior wall, sleeved and sealed where it penetrates

Under NAC 624.190(f), a Nevada C-1F Heating, Cooling and Circulating Air license authorizes fabrication and installation of heating, evaporative cooling, and air-circulation systems. Which of the following is expressly outside that scope?

• AA gas-fired warm-air furnace and its supply ducts
• BA roof-mounted evaporative cooler (swamp cooler)
• CA cooling system that uses refrigeration as an integral part of the system
• DSolar equipment used for space heating or air circulation

An evaporative cooler (swamp cooler) lowers the temperature of supply air primarily by:

• ACompressing a refrigerant and rejecting heat at a condenser coil
• BSensible cooling only, with no change in air moisture content
• CEvaporating water into the air stream so latent heat is absorbed and the dry-bulb tempera…
• DCirculating chilled water from a refrigeration plant through a coil

A Category I gas furnace is best described as an appliance that operates with:

• AA positive-pressure, condensing vent that may be PVC
• BA positive-pressure, non-condensing stainless special-gas vent only
• CA non-positive vent pressure and a flue-gas temperature that avoids excessive condensatio…
• DNo vent, because all combustion air and exhaust stay inside the heat exchanger

The listed vent typically used for a Category I natural-draft or fan-assisted gas furnace is:

• AType B double-wall gas vent
• BSchedule 40 PVC sewer pipe
• CSingle-wall stovepipe run the full height through the roof
• DType L vent listed only for oil appliances

A 95 percent AFUE condensing gas furnace (Category IV) must be vented with:

• AType B vent, because all gas furnaces use Type B
• BAn unlined masonry chimney shared with a wood fireplace
• CThe vent material and termination listed with the appliance, typically PVC, CPVC, or poly…
• DA single-wall connector only, with no vertical vent

A listed warm-air furnace installed under the 2018 UMC shall be installed:

• ATo any locally improvised layout, provided the gas pipe is sized
• BIn accordance with the listing and the manufacturer's installation instructions, and the…
• CWith zero clearance on all sides to save closet space
• DOutdoors only; indoor furnaces are no longer listed

Return air for a forced-air heating system shall not be taken from which of the following locations?

• AA central hallway in the conditioned dwelling
• BA bathroom, toilet room, kitchen, garage, or other space that can contain contaminants or…
• CA living room through a listed grille
• DA return plenum in the conditioned basement, properly filtered