Nevada C-21F Chilled and Hot Water Systems Contractor Examination

Per NAC 624.380, Nevada C-21F chilled and hot water systems work includes installation of which of the following?

• ABoilers, chillers, coils, cooling towers, piping, pumps, storage tanks, and valves used t…
• BChilled-water piping only, with no authority to install or connect a chiller
• CDirect-expansion refrigerant piping inside a packaged rooftop unit only
• DPotable plumbing fixtures and sanitary drainage stacks

A closed hydronic chilled- or hot-water loop is best described as which of the following?

• AAn open basin that continuously dumps circulating water to the sanitary sewer
• BA sealed, pressurized circuit that recirculates the same treated water through the plant,…
• CA once-through city-water line that discharges after a single pass through the coil
• DA potable-water distribution system serving lavatories and water closets

On a chemically treated closed chilled- or hot-water loop, which ferrous pipe is the ordinary above-ground commercial choice?

• AUnlisted fence tubing with no ASTM mark
• BGalvanized thin-wall EMT conduit
• CASTM A53 Grade B Schedule 40 black steel, joined by welding, grooving, flanging, or threa…
• DSchedule 160 A106 steam pipe on every 1-inch branch

Hydronic pipe, tubing, and fittings used on a C-21F chilled- or hot-water system must comply with which UMC 2018 source?

• AAny hardware-store hose that holds shop air
• BUMC Table 1210.1 listed materials rated for the system temperature, pressure, and fluid
• CType DWV copper only, because hydronic water is not a pressure service
• DUnlisted irrigation tubing painted the system color

Where copper hydronic tube is joined to carbon-steel pipe or a steel pump flange, UPC 2018 Sections 605.15 and 605.16 require which fitting?

• AA sanitary tee laid on its back
• BA no-hub shielded coupling listed only for cast-iron DWV
• CA brass cleanout plug
• DA dielectric union or other listed dielectric fitting

The extra duty of insulation on chilled-water pipe, compared with hot-water pipe, is to:

• AProvide a continuous vapor retarder so room-air moisture cannot condense on the cold pipe
• BRaise the circulating water to 180°F
• CReplace the need for pipe hangers
• DAllow the pipe to be tested with oxygen

Per UMC 2018 Section 1204.5, hydronic piping identification shall be placed at which interval?

• AEvery 100 feet, and only in the mechanical room
• BOnly at the building entrance
• CEvery 20 feet, but not less than once per room, and visible from the floor
• DIdentification is never required on closed loops

Per UMC 2018 Section 1205.3, what must be done to heating and cooling sources and system piping after installation?

• ALeave mill scale and cutting oil in the loop so inhibitors have something to react with
• BFlush with water or a cleaning solution compatible with all system components, following…
• CBlow the loop out with oxygen
• DFill with untreated well water and place the chiller in service immediately

Which ASTM B88 copper water-tube type is the everyday above-ground hydronic choice on C-21F work?

• AType DWV (yellow), because hydronic water is drainage
• BType M only, because it is required underground
• CType K only, because Type L is illegal indoors
• DType L (blue mark), with Type K often reserved for burial and Type M the thinner above-gr…

UMC 2018 Section 1205.2 requires hydronic piping and components to be tested at:

• AOperating pressure for 5 minutes
• B10 psi air for 15 minutes on every plastic and steel system
• CNot less than 1.5 times the operating pressure, and not less than 100 psi, held at least…
• DAny pressure the job-site compressor can reach

Under UMC 2018 Section 1205.2, plastic hydronic pipe shall not be tested with air except:

• AWhenever the crew wants a faster test
• BFor listed PEX, PP-R, PP-RCT, PEX-AL-PEX, PE-RT, and PE-AL-PE systems whose manufacturer…
• CWhenever the test pressure exceeds 200 psi
• DOn every PVC DWV stack used as a hydronic riser

Per UMC 2018 Table 313.3, horizontal steel water or hydronic pipe 1 inch and larger shall be supported at intervals not exceeding:

• A4 feet
• B6 feet
• C12 feet
• D25 feet

Per UMC 2018 Table 313.3, horizontal copper or copper-alloy pipe 1-1/2 inches and smaller shall be supported at least every:

• A32 inches
• B6 feet
• C12 feet
• D15 feet

PEX tubing used on a closed hydronic loop that also contains steel pumps, tanks, or boilers should be which product?

• AOxygen-barrier PEX (or PEX-AL-PEX) listed for hydronic service in UMC Table 1210.1
• BNon-barrier plumbing PEX, because oxygen helps the inhibitors
• CPEX-AL-PEX only if the aluminum layer is perforated
• DAny orange electrical HDPE conduit

Which gasket compound is the ordinary choice for grooved couplings on a chilled-water or inhibited-glycol hydronic loop?

• ACompressed asbestos sheet leftover from an old steam job
• BUnlisted paper fiber cut from a carton
• CEPDM (or the coupling manufacturer's equivalent hydronic compound)
• DLead wool

Long straight runs of hot-water steel mains need expansion loops, offsets, or expansion joints primarily to:

• AIncrease pump head so the circulator can run faster
• BAbsorb thermal growth so anchors and connected equipment are not overloaded
• CReplace the expansion tank required by UMC 1209.1
• DConvert the closed loop into an open drain

Why is Type K copper often specified for underground chilled- or hot-water tube instead of Type M?

• AType K has the thickest ASTM B88 wall and better resists burial damage and corrosion allo…
• BType K is the thinnest water tube and is cheaper to bury
• CType M is required underground by ASTM B88
• DType K is yellow DWV tube

In a primary-secondary hydronic plant, the short common pipe (decoupler) between the primary and secondary loops is provided so that:

• AThe two loops can operate at independent flows without hydraulic fighting
• BCity water can dump continuously into the chilled-water return
• CThe expansion tank can be omitted
• DThe secondary pump can be eliminated

Compared with a direct-return hydronic layout, a reverse-return layout is used because:

• AIt automatically makes every circuit the same equivalent length so coils are easier to ba…
• BIt eliminates the need for isolation valves at coils
• CIt converts the system to once-through city water
• DIt allows Type DWV copper on the mains

High points of a closed chilled- or hot-water circuit should be provided with which devices?

• AAutomatic or manual air vents so trapped air can be removed
• BSanitary cleanouts that discharge into a soil stack
• CFuel-gas drip legs
• DNo devices; air will dissolve if the pump is oversized

Outdoor chilled- or hot-water insulation must be protected by which covering?

• ABare ASJ left in the sun
• BA single wrap of cloth duct tape
• CA weather jacket suitable for outdoor service, such as aluminum, stainless, or a listed o…
• DNo cover if the insulation is white

A closed hydronic loop will be filled with 30 percent inhibited propylene glycol. What must the C-21F contractor check before selecting gaskets, valve seats, pumps, and plastic pipe?

• AGlycol always allows any rubber or plastic because it is food-grade
• BGlycol makes copper illegal under UMC Table 1210.1
• CThe fluid's chemical compatibility and the reduced heat capacity and higher viscosity mus…
• DGlycol requires Type DWV copper only

Flexible hose connectors at a hydronic pump, chiller, or air handler are acceptable when they are:

• AOrdinary garden hose clamped with worm-drive clamps
• BRequired to be the only pipe support on the main
• CMade of unlisted automotive heater hose on every 8-inch riser
• DListed for the temperature, pressure, and fluid, installed without twist, and aligned so…

Used pipe, fittings, and valves may be installed on a new C-21F hydronic system only when they are:

• AFree of foreign materials and defects and still comply with the listed material standards…
• BPainted the same color as the new pipe, regardless of wall thickness
• CTaken from a sanitary sewer and flushed once
• DAlways forbidden, even if they are listed and undamaged

An 80-ton chilled-water coil is selected for a 12°F delta-T. Using gpm = tons × 24 / ΔT, what chilled-water flow is required?

• A80 gpm
• B160 gpm
• C240 gpm
• D960 gpm

A closed hydronic loop will operate at 70 psi. What is the minimum UMC 1205.2 test pressure, and how long must it hold with no perceptible drop?

• A70 psi for 10 minutes
• B100 psi for 15 minutes
• C105 psi for 30 minutes
• D210 psi for 60 minutes

A designer sizes a heating-water main for 4 feet of friction per 100 feet of pipe. If the equivalent length of the circuit (pipe plus fittings) is 400 feet, the pipe-friction head is:

• A4 feet
• B16 feet
• C40 feet
• D400 feet

A 3-inch Schedule 40 steel hydronic main (inside diameter 3.068 inches) carries 150 gpm. Using V = 0.4085 × Q / d², the mean velocity is closest to:

• A3.5 feet per second
• B6.5 feet per second
• C10.0 feet per second
• D15.0 feet per second

The expansion tank connection is the point of no pressure change. How should the system circulator be piped relative to that point?

• APump toward the expansion tank so the pump subtracts from fill pressure at its suction
• BPump away from the expansion tank so the pump adds its head to the fill pressure
• CMount the expansion tank on the pump discharge only
• DOmit the expansion tank if the pump is a wet-rotor circulator

A hydronic pump must deliver 200 gpm. Pipe-friction head is 18 feet, the coil is 12 feet, the control valve is 8 feet, and the strainer is 3 feet. What pump total dynamic head should be used, and what is the water horsepower using WHP = gpm × head / 3960?

• A18 feet and 0.9 WHP
• B41 feet and 2.1 WHP
• C200 feet and 10.4 WHP
• D8 feet and 0.4 WHP

What is the primary job of a water chiller on a C-21F system?

• ATo add heat to the building heating-water loop
• BTo remove heat from circulating chilled water so coils can cool occupied space
• CTo dump untreated city water through a cooling coil and to drain
• DTo generate high-pressure steam for turbines

A Nevada contractor is hired to set a water-cooled chiller, connect its evaporator and condenser barrels, and start the machine. Which classification authorizes that work?

• AC-1I chilled-water piping, because the last sentence of NAC 624.190(2)(i) includes chille…
• BC-21F chilled and hot water systems, which expressly includes chillers
• CC-1H water heaters only
• DNo contractor classification; any unlicensed crew may connect a chiller

What is the primary job of a cooling tower serving a water-cooled chiller?

• ATo refrigerate the building air directly with refrigerant coils
• BTo reject condenser heat to the outdoor air by evaporating a small fraction of the circul…
• CTo heat the boiler return so the condensing boiler can run
• DTo store potable water for fire sprinklers

A common design temperature pair for a commercial chilled-water coil is:

• A180°F supply / 160°F return
• B44°F supply / 56°F return
• C212°F supply / 212°F return
• D95°F supply / 85°F return

A common design temperature pair for condenser water between a water-cooled chiller and a cooling tower is:

• A44°F to the tower / 56°F back to the chiller
• B180°F to the tower / 160°F back to the chiller
• C95°F to the tower / 85°F back to the chiller
• D32°F to the tower / 40°F back to the chiller

What does a chilled-water cooling coil in an air handler do?

• AIt transfers heat from the airstream into the chilled water so the air leaves cooler and…
• BIt boils refrigerant to heat the building
• CIt is the cooling-tower fill
• DIt stores expansion volume for the closed loop

Compared with an air-cooled chiller, a water-cooled chiller typically needs which extra C-21F equipment?

• AA cooling tower, condenser-water pumps, and condenser-water piping
• BA steam boiler in series with the evaporator
• CNo circulating water at all
• DA sanitary ejector in the refrigerant circuit

Cooling-tower range and approach are defined as which pair?

• ARange is leaving water minus wet bulb; approach is entering water minus leaving water
• BRange is entering water minus leaving water; approach is leaving water minus outdoor wet-…
• CRange and approach are both the same as chilled-water delta-T
• DRange is fan horsepower; approach is basin volume

An induced-draft cooling tower is distinguished from a forced-draft tower by which fan location?

• AThe fan is at the air outlet and pulls air through the fill (induced draft)
• BThere is never a fan on an induced-draft tower
• CThe fan is always inside the chiller evaporator barrel
• DInduced draft means the tower is underground with no air path

What is the purpose of drift eliminators in a cooling tower?

• ATo increase basin volume so the tower can store fire water
• BTo capture water droplets that would otherwise leave with the exhaust air
• CTo heat the entering condenser water
• DTo replace the need for makeup-water treatment

A cooling-tower basin should be provided with which two water-side accessories?

• AA strainer or screen on the pump suction and a makeup valve with backflow protection
• BA boiler safety valve piped into the basin
• CA fuel-oil fill cap
• DA sanitary ejector discharging into the condenser

Per UMC 2018 Section 1212.6, a serviceable chiller evaporator or condenser connection must have:

• ANo valves, so the barrels cannot be isolated
• BIsolation valves installed upstream and downstream of the device
• CA single screwdriver stop hidden above the ceiling
• DA sanitary trap on the refrigerant line

On a water-cooled chiller, which statement correctly pairs the two shells with their water loops?

• AThe evaporator cools chilled water; the condenser rejects heat into condenser water
• BThe evaporator heats the cooling tower; the condenser cools the building
• CBoth shells circulate potable hot water at 140°F
• DThe condenser is a steam boiler drum

A cooling tower should be located so that:

• ADischarge air can recirculate into the intake and into nearby outdoor-air intakes
• BLeaving air is free to rise and cannot short-circuit back into the intake or into buildin…
• CThe tower sits in a tightly boxed well with no relief path
• DThe basin overflows onto a public sidewalk as the only drain