refrigerant piping a trane air conditioning clinic air conditioning clinic trg-trc006-en © american...

Refrigerant PipingA Trane Air Conditioning Clinic

Air Conditioning Clinic TRG-TRC006-ENAir Conditioning Clinic TRG-TRC006-EN© American Standard Inc. 2002

period one

Refrigerant Piping Requirements

Refrigerant Piping



Vapor-Compression Refrigeration

expansionexpansiondevicedevice

condensercondenser

compressorcompressor

evaporatorevaporatorA B

CD


Interconnecting Refrigerant Piping


condensercondenser

evaporatorevaporator

expansion deviceexpansion device

dischargedischargelineline

suctionsuctionlineline

liquidliquidlineline

A

B

C

D


Refrigerant Piping Requirements

Return oil to compressor Ensure that only liquid refrigerant enters

the expansion device Minimize system capacity loss Minimize refrigerant charge Insulate lines that are routed through very

warm spaces (Liquid line)


Scroll Compressor

stationarystationaryscrollscroll

drivendrivenscrollscroll

intakeintake

dischargedischarge

intakeintake

dischargedischargeportport

motormotorshaftshaft

sealseal


Return Oil to Compressors


condensercondenser


expansion expansion devicedevice




warmwarmliquidliquid

hothotvaporvapor

coolcoolvaporvapor


Thermostatic Expansion Valve (TXV)

external equalizerexternal equalizer

remote remote bulbbulb


TXVTXV

refrigerantrefrigerantvaporvapor

distributordistributor

liquid liquid refrigerantrefrigerant


Subcooling

B

A

pres

sure

pres

sure

enthalpyenthalpy

{

subcoolingsubcooling

C

mixture of liquid mixture of liquid and vaporand vapor

saturatedsaturatedvapor curvevapor curve

saturatedsaturatedliquid curveliquid curve

expansionexpansiondevicedevice

condensercondenser




Condenser

Evaporator

CompressorExpansion

Device


Pressure Drop in a Suction Lineim

pact

on

syst

em p

erfo

rman

ce, %

impa

ct o

n sy

stem

per

form

ance

, %

capacitycapacitycapacitycapacity

100100

efficiencyefficiencyefficiencyefficiency

pressure drop, psipressure drop, psi (kPa)(kPa)pressure drop, psipressure drop, psi (kPa)(kPa)

22(13.8)(13.8)

22(13.8)(13.8)

9696

9292

9898

9494

909044

(27.6)(27.6)44

(27.6)(27.6)66

(41.4)(41.4)66

(41.4)(41.4)1010

(69.0)(69.0)1010

(69.0)(69.0)1212

(82.7)(82.7)1212

(82.7)(82.7)88

(55.2)(55.2)88

(55.2)(55.2)

R-22R-22R-22R-22


Minimize Refrigerant Charge

liquid lineliquid line suction linesuction line

condensercondenser


filterfilterdrierdrier

compressorcompressordischargedischargelineline


Involve the Manufacturer

If provided, use refrigerant line sizes recommended by manufacturer


General Piping Requirements

Use clean Type L copper tubing Copper-to-copper joints: BCuP-6 without flux Copper-to-steel (or brass) joints: BAg-28, non-acid flux

Properly support piping to account for expansion, vibration, and weight

Avoid installing piping underground Test entire refrigerant circuit for leaks

period two

Suction Line

Refrigerant Piping



suction line

Requirements for Sizing and Routing

Ensure adequate velocity to return oil to compressor at all steps of unloading

Avoid excessive noise Minimize system capacity and efficiency loss


suction line Sizing “Rules”

minimum velocity

1,000 fpm (5 m/s) based on diameter of riserfor vertical risers

500 fpm (2.5 m/s) percentage of minimum for horizontal sections riser velocity

maximum velocity

4,000 fpm (20 m/s) 4,000 fpm (20 m/s)

maximum pressure drop

3 psi (20 kPa) based on specific system requirements

old rules for R-22 new rules for R-22


suction line Process for Sizing

1 Determine total length of piping

2 Calculate refrigerant velocity at maximum and minimum capacities

3 Select largest pipe diameter that results in acceptable velocity at both maximum and minimum capacities

4 Calculate total equivalent length of straight pipe and fittings

5 Determine pressure drop due to pipe and fittings

6 Add pressure drop due to accessories


Unloading Refrigeration Circuits

reciprocating compressorreciprocating compressorwith cylinder unloaderswith cylinder unloaders scroll compressorsscroll compressors

manifolded on amanifolded on asingle circuitsingle circuit


velo

city,

fpm

(m/s

)ve

locit

y, fp

m (m

/s)

evaporator capacity, tons (kW)evaporator capacity, tons (kW)

11(3.5)(3.5)

55(17.6)(17.6)

1010(35)(35)

5050(176)(176)

100100(352)(352)

200200(703)(703)

1,0001,000(5.1)(5.1)

500500(2.5)(2.5)

2,0002,000(10.2)(10.2)

5,0005,000(25.4)(25.4)

2020(70)(70)

22(7.0)(7.0)

1/2 (1

2)

1/2 (1

2)

5/8 (1

5)

5/8 (1

5)

7/8 (2

2)

7/8 (2

2)

1 1/8

(28)

1 1/8

(28)

1 3/8

(35)

1 3/8

(35)

1 5/8

(42)

1 5/8

(42)

2 1/8

(54)

2 1/8

(54)

2 5/8

(67)

2 5/8

(67)

3 1/8

(79)

3 1/8

(79)

3 5/8

(105)

3 5/8

(105)

R-22R-22

suction line

Determine Refrigerant Velocitypipe diameter, in. (mm)pipe diameter, in. (mm)

3/8 (1

0)

3/8 (1

0)

4 1/8

(130)

4 1/8

(130)3/4

(18)

3/4 (1

8)


suction line

Determine Refrigerant Velocity

velocity, fpm (m/s)velocity, fpm (m/s)pipepipediameter,diameter,in. (mm)in. (mm)

20 tons 20 tons (70.3 kW)(70.3 kW)

10 tons 10 tons (35.2 kW)(35.2 kW)

1 1/8 (28)1 1/8 (28) 7,000 (35.6)7,000 (35.6) 3,500 (17.8)3,500 (17.8)1 3/8 (35)1 3/8 (35) 4,600 (23.4)4,600 (23.4) 2,300 (11.7)2,300 (11.7)1 5/8 (42)1 5/8 (42) 3,250 (16.5)3,250 (16.5) 1,625 (8.3)1,625 (8.3)2 1/8 (54)2 1/8 (54) 1,850 (9.4)1,850 (9.4) 925 (4.7) 925 (4.7)2 5/8 (67)2 5/8 (67) 1,200 (6.1)1,200 (6.1) 600 (3.1) 600 (3.1)3 1/8 (79)3 1/8 (79) 850 (4.3)850 (4.3) 425 (2.2) 425 (2.2)


riserriser horiz/drophoriz/drop3/8 (10)3/8 (10) 370 (1.9)370 (1.9) 275 (1.4)275 (1.4)1/2 (12)1/2 (12) 460 (2.3)460 (2.3) 350 (1.8)350 (1.8)5/8 (15)5/8 (15) 520 (2.6)520 (2.6) 390 (2.0)390 (2.0)3/4 (18)3/4 (18) 560 (2.8)560 (2.8) 420 (2.1)420 (2.1)7/8 (22)7/8 (22) 600 (3.1)600 (3.1) 450 (2.3)450 (2.3)

1 1/8 (28)1 1/8 (28) 700 (3.6)700 (3.6) 525 (2.7)525 (2.7)1 3/8 (35)1 3/8 (35) 780 (4.0)780 (4.0) 585 (3.0)585 (3.0)1 5/8 (42)1 5/8 (42) 840 (4.3)840 (4.3) 630 (3.2)630 (3.2)2 1/8 (54)2 1/8 (54) 980 (5.0)980 (5.0) 735 (3.7)735 (3.7)2 5/8 (67)2 5/8 (67) 1,080 (5.5)1,080 (5.5) 810 (4.1)810 (4.1)3 1/8 (79)3 1/8 (79) 1,180 (6.0)1,180 (6.0) 885 (4.5)885 (4.5)

3 5/8 (105)3 5/8 (105) 1,270 (6.5)1,270 (6.5) 950 (4.8)950 (4.8)4 1/8 (130)4 1/8 (130) 1,360 (6.9)1,360 (6.9) 1,020 (5.2)1,020 (5.2)

suction line

Minimum Allowable Velocitiesminimum velocity, fpm (m/s)minimum velocity, fpm (m/s)pipe diameter,pipe diameter,

in. (mm)in. (mm)


Select Suction Line Size

riserriser horiz/drophoriz/drop

20 (70.3)20 (70.3) 1,850 (9.4)1,850 (9.4)

10 (35.2)10 (35.2) 925 (4.7)925 (4.7)

circuitcircuitcapacity,capacity,tons (kW)tons (kW)

minimum velocity for 2 1/8 in.minimum velocity for 2 1/8 in.(54 mm) pipe, fpm (m/s)(54 mm) pipe, fpm (m/s)

velocity insidevelocity inside2 1/8 in. (54 mm) 2 1/8 in. (54 mm) pipe, fpm (m/s)pipe, fpm (m/s)

980 (5.0)980 (5.0) 735 (3.7)735 (3.7)


20 (70.3)20 (70.3) 3,250 (16.5)3,250 (16.5)

10 (35.2)10 (35.2) 1,625 (8.3)1,625 (8.3)




840 (4.3)840 (4.3) 630 (3.2)630 (3.2)


Selected Suction Line Sizes



2 1/8 in.2 1/8 in.(54 mm)(54 mm)

1 5/8 in. 1 5/8 in. (42 mm)(42 mm)riserriser

2 1/8 in.2 1/8 in.(54 mm)(54 mm)

dropdrop


Double Suction Riser

20 (70.3)20 (70.3) 3,250 (16.5)3,250 (16.5)

5 (17.6)5 (17.6) 810 (4.1)810 (4.1)


minimum velocity forminimum velocity for1 5/8 in. (42 mm) riser, 1 5/8 in. (42 mm) riser,

fpm (m/s)fpm (m/s)


840 (4.3)840 (4.3)

20 (70.3)20 (70.3) 4,600 (23.4)4,600 (23.4)

5 (17.6)5 (17.6) 1,150 (5.9)1,150 (5.9)


minimum velocity forminimum velocity for1 3/8 in. (35 mm) riser, 1 3/8 in. (35 mm) riser,

fpm (m/s)fpm (m/s)


780 (4.0)780 (4.0)


Double Suction Riser

largerlargerriserriser

smallersmallerriserriser

traptrap


Sizing a Double Suction Riser

Sizing the smaller riser

Sizing the larger riser

5 (17.6)5 (17.6) 1,150 (5.8)1,150 (5.8)


minimum velocityminimum velocityfor 1 3/8 in. (35 mm) for 1 3/8 in. (35 mm) riser, fpm (m/s)riser, fpm (m/s)


780 (4.0)780 (4.0)

15 (52.8)15 (52.8) 2,450 (12.4)2,450 (12.4)


minimum velocityminimum velocityfor 1 5/8 in. (42 mm) for 1 5/8 in. (42 mm) riser, fpm (m/s)riser, fpm (m/s)


840 (4.3)840 (4.3)


Calculate Total Equivalent Length

LLeqeq is based on r/d is based on r/d

radius of curvature (r)radius of curvature (r)

diameter (d)diameter (d)


Leq for Long-Radius Elbows

equivalent length, ft (m)equivalent length, ft (m)

““old” dataold” data ““new” datanew” data

1 1/8 (28)1 1/8 (28) 1.9 (0.6)1.9 (0.6) 0.8 (0.24)0.8 (0.24)1 3/8 (35)1 3/8 (35) 2.2 (0.7)2.2 (0.7) 0.9 (0.27)0.9 (0.27)1 5/8 (42)1 5/8 (42) 2.6 (0.8)2.6 (0.8) 1.0 (0.30)1.0 (0.30)2 1/8 (54)2 1/8 (54) 3.4 (1.0)3.4 (1.0) 1.4 (0.43)1.4 (0.43)2 5/8 (67)2 5/8 (67) 4.2 (1.3)4.2 (1.3) 1.5 (0.46)1.5 (0.46)3 1/8 (79)3 1/8 (79) 5.1 (1.6)5.1 (1.6) 1.7 (0.52)1.7 (0.52)

elbowelbowdiameter,diameter,in. (mm)in. (mm)


pres

sure

dro

p, p

si/10

0 ft

(kPa

/10

m)

pres

sure

dro

p, p

si/10

0 ft

(kPa

/10

m)


11(3.5)(3.5)

55(17.6)(17.6)

1010(35)(35)

5050(176)(176)

100100(352)(352)

200200(703)(703)

1.01.0(2.3)(2.3)

0.50.5(1.2)(1.2)

2.02.0(4.6)(4.6)

5.05.0(11.5)(11.5)

2020(70)(70)

22(7.0)(7.0)

2 1/

8 (5

4)2

1/8

(54)

2 5/

8 (6

7)2

5/8

(67)

3 1/

8 (7

9)3

1/8

(79)

R-22R-22

pipe diameter, in. (mm)pipe diameter, in. (mm)

1 5/

8 (4

2)1

5/8

(42)10.010.0

(23.0)(23.0)

suction line

Determine Pressure Drop

1 3/

8 (3

5)1

3/8

(35)

1 1/

8 (2

8)1

1/8

(28)

7/8

(22)

7/8

(22)

3/4

(18)

3/4

(18)

5/8

(15)

5/8

(15)

3 5/

8 (1

05)

3 5/

8 (1

05)

4 1/

8 (1

30)

4 1/

8 (1

30)


suction line

Add Pressure Drop of Accessories

Suction filter = 2 psi (13.8 kPa) Angle valve = 1 psi (6.9 kPa) Ball valve = 1 equivalent ft (0.3 m)

suction line filtersuction line filter


TXV Installation

external equalizer lineexternal equalizer line

remote remote bulbbulb


TXVTXV

refrigerantrefrigerantvaporvapor


liquid liquid refrigerantrefrigerant


single distributor on circuit

Evaporator Coil Connection

TXVTXVbulbbulb

must rise abovemust rise aboveheight of evaporatorheight of evaporator

must drop belowmust drop belowheader outletheader outlet

suction headersuction header


multiple distributors on circuit Evaporator Coil Connections

TXVTXVbulbbulb

must drop belowmust drop belowlowest header outletlowest header outlet double-elbowdouble-elbow

configurationconfiguration

must rise abovemust rise aboveheight of evaporatorheight of evaporator


suction line

Riser Traps Are Not Required


suction line Other Considerations Do not use suction riser traps: they are not

required Pitch horizontal sections to drain toward

evaporator Insulate entire suction line

Prevents condensation Minimizes loss of capacity due to heat gain

Install suction-line filter close to compressor Manual shutoff valves allow isolation for replacement

Install access ports to measure suction pressure and superheat


Suction-Line Accumulator

Check with equipment manufacturer to determine if required, recommended, or discouraged

photo provided by Henry Technologiesphoto provided by Henry Technologies


suction line

Reciprocating Compressors

pipepipeanchoranchor

pitchpitch

period three

Discharge Line

Refrigerant Piping



discharge line


Ensure adequate velocity to return oil to compressor at all steps of unloading

Avoid excessive noise Minimize efficiency loss


discharge line Sizing “Rules”

minimum velocity

1,000 fpm (5 m/s) based on diameter of riserfor risers

500 fpm (2.5 m/s) percentage of minimum for horizontal sections riser velocity

maximum velocity

3,500 fpm (17.5 m/s) 3,500 fpm (17.5 m/s)


6 psi (41 kPa) based on specific system requirements



discharge line Process for Sizing


2 Calculate refrigerant velocity at maximum and minimum capacities

3 Select largest pipe diameter that results in acceptable velocity at both maximum and minimum capacity

4 Calculate total equivalent length of straight pipe and fittings




11(3.5)(3.5)

55(17.6)(17.6)

1010(35)(35)

5050(176)(176)

100100(352)(352)

200200(703)(703)

1,0001,000(5.1)(5.1)

500500(2.5)(2.5)

2,0002,000(10.2)(10.2)

5,0005,000(25.4)(25.4)

2020(70)(70)

22(7.0)(7.0)

1/2 (1

2)

1/2 (1

2)

5/8 (1

5)

5/8 (1

5)

7/8 (2

2)

7/8 (2

2)

1 1/8

(28)

1 1/8

(28)

1 3/8

(35)

1 3/8

(35)

1 5/8

(42)

1 5/8

(42)

2 1/8

(54)

2 1/8

(54)

2 5/8

(67)

2 5/8

(67)

3 1/8

(79)

3 1/8

(79)

R-22R-22

discharge line


velo

city,

fpm

(m/s

)ve

locit

y, fp

m (m

/s)



3/8 (1

0)

3/8 (1

0)

3/4 (1

8)

3/4 (1

8)

5/16 (

8)

5/16 (

8)


discharge line


7/8 (22)7/8 (22) 4,050 (20.6)4,050 (20.6) 2,025 (10.3)2,025 (10.3)1 1/8 (28)1 1/8 (28) 2,400 (12.2)2,400 (12.2) 1,200 ( 6.1)1,200 ( 6.1)1 3/8 (35)1 3/8 (35) 1,550 ( 7.9)1,550 ( 7.9) 775 ( 3.9) 775 ( 3.9)1 5/8 (42)1 5/8 (42) 1,100 ( 5.6)1,100 ( 5.6) 550 ( 2.8) 550 ( 2.8)2 1/8 (54)2 1/8 (54) 650 ( 3.3)650 ( 3.3) 325 ( 1.7) 325 ( 1.7)


20 tons 20 tons (70.3 kW)(70.3 kW)

10 tons 10 tons (35.2 kW)(35.2 kW)


discharge line

Minimum Allowable Velocities

riserriser horiz/drophoriz/drop5/16 (8)5/16 (8) 220 (1.1)220 (1.1) 165 (0.8)165 (0.8)3/8 (10)3/8 (10) 250 (1.3)250 (1.3) 185 (0.9)185 (0.9)1/2 (12)1/2 (12) 285 (1.4)285 (1.4) 215 (1.1)215 (1.1)5/8 (15)5/8 (15) 315 (1.6)315 (1.6) 235 (1.2)235 (1.2)3/4 (18)3/4 (18) 345 (1.8)345 (1.8) 260 (1.3)260 (1.3)7/8 (22)7/8 (22) 375 (1.9)375 (1.9) 285 (1.4)285 (1.4)

1 1/8 (28)1 1/8 (28) 430 (2.2)430 (2.2) 325 (1.7)325 (1.7)1 3/8 (35)1 3/8 (35) 480 (2.4)480 (2.4) 360 (1.8)360 (1.8)1 5/8 (42)1 5/8 (42) 520 (2.6)520 (2.6) 390 (2.0)390 (2.0)2 1/8 (54)2 1/8 (54) 600 (3.0)600 (3.0) 450 (2.3)450 (2.3)2 5/8 (67)2 5/8 (67) 665 (3.4)665 (3.4) 500 (2.5)500 (2.5)3 1/8 (79)3 1/8 (79) 730 (3.7)730 (3.7) 550 (2.8)550 (2.8)

minimum velocity, fpm (m/s)minimum velocity, fpm (m/s)pipe diameter,pipe diameter,in. (mm)in. (mm)


Select Discharge Line Size


20 (70.3)20 (70.3) 1,100 (5.6)1,100 (5.6)

10 (35.2)10 (35.2) 550 (2.8)550 (2.8)




520 (2.6)520 (2.6) 390 (2.0)390 (2.0)


Selected Discharge Line Size

1 5/8 in.1 5/8 in.(42 mm)(42 mm)


condensercondenser 1 5/8 in. 1 5/8 in. (42 mm)(42 mm)riserriser

1 5/8 in. 1 5/8 in. (42 mm)(42 mm)


pres

sure

dro

p, p

si/10

0 ft

(kPa

/10

m)

pres

sure

dro

p, p

si/10

0 ft

(kPa

/10

m)


11(3.5)(3.5)

55(17.6)(17.6)

1010(35)(35)

5050(176)(176)

100100(352)(352)

200200(703)(703)

1.01.0(2.3)(2.3)

0.50.5(1.2)(1.2)

2.02.0(4.6)(4.6)

5.05.0(11.5)(11.5)

2020(70)(70)

22(7.0)(7.0)

7/8

(22)

7/8

(22)

1 1/8

(28)

1 1/8

(28)

1 3/8

(35)

1 3/8

(35)

2 1/8

(54)

2 1/8

(54)

2 5/8

(67)

2 5/8

(67)

3 1/8

(79)

3 1/8

(79)

R-22R-22


1 5/8

(42)

1 5/8

(42)

10.010.0(23.0)(23.0)

discharge line

Determine Pressure Drop

3/4

(18)

3/4

(18)

5/8

(15)

5/8

(15)

1/2

(12)

1/2

(12)


discharge line


Angle valve = 1 psi (6.9 kPa) Ball valve = 1 equivalent ft (0.3 m)


discharge line Other Considerations

Do not use discharge riser traps: they are not required

Pitch horizontal sections to drain toward condenser

Insulate only to prevent accidental burns or when system must operate in cold ambient conditions


discharge line

Reciprocating Compressors

pipepipeanchoranchor

pitchpitch

period four

Liquid Line

Refrigerant Piping



liquid line


Ensure that only liquid refrigerant enters expansion device

Minimize refrigerant charge Avoid excessive noise and pipe erosion


Subcooling

enthalpy, Btu/lb (kJ/kg)enthalpy, Btu/lb (kJ/kg)

241241(1,662)(1,662)

pres

sure

, psia

(kPa

)pr

essu

re, p

sia (k

Pa)

293293(2,020)(2,020) 125°F125°F

(51.7°C)(51.7°C)

subcoolingsubcooling

saturatedsaturatedliquid curveliquid curve

mixture of liquidmixture of liquidand vaporand vapor

110°F110°F(43.3°C)(43.3°C)

{


Impact of Refrigerant Density Change

AA 7/8 (22)7/8 (22) highhigh 18.0 (10) -18.0 (10) - 5.7 (3.2) =5.7 (3.2) = 12.3 (6.8)12.3 (6.8)BB 1 1/8 (28)1 1/8 (28) highhigh 18.0 (10) -18.0 (10) - 3.8 (2.1) =3.8 (2.1) = 14.2 (7.9)14.2 (7.9)

AA 7/8 (22)7/8 (22) lowlow 12.9 (7.2) -12.9 (7.2) - 7.4 (4.1) =7.4 (4.1) = 5.5 (3.1)5.5 (3.1)BB 1 1/8 (28)1 1/8 (28) lowlow 7.2 (4.0) -7.2 (4.0) - 5.2 (2.9) =5.2 (2.9) = 2.0 (1.1)2.0 (1.1)

available subcooling, °F (°C)available subcooling, °F (°C)liquid lineliquid linediameter, diameter, in. (mm)in. (mm)

leaving leaving subcoolersubcooler

loss due loss due to pipingto piping

outdooroutdoortemperaturetemperature remaining remaining

at TXVat TXV


liquid line Sizing “Rules”


6 psi (41 kPa) 5°F (2.8°C) subcoolingremaining at inlet to expansion device at all operating conditions

maximum velocity

360 fpm (1.8 m/s) 600 fpm (3 m/s)



liquid line Process for Sizing


2 Obtain subcooling provided by condenser

3 Determine refrigerant velocity

4 Select smallest pipe diameter that results in acceptable velocity at maximum capacity

5 Calculate total equivalent length of pipe and fittings



8 Calculate loss of subcooling due to pressure drop and elevation change


System Operating Envelope

saturated suction temperaturesaturated suction temperature

condensing unit,condensing unit,high OA temperaturehigh OA temperature

condensing unit, condensing unit, low OA temperaturelow OA temperature

evaporator,evaporator,high cooling loadhigh cooling load

evaporator,evaporator,low cooling loadlow cooling load

syst

em c

oolin

g ca

pacit

ysy

stem

coo

ling

capa

city


System Operating Envelope

high cooling load,high cooling load,high OA temperaturehigh OA temperature

A

B

D

C

high cooling load,high cooling load,low OA temperaturelow OA temperature

low cooling load,low cooling load,high OA temperaturehigh OA temperature

low cooling load,low cooling load,low OA temperaturelow OA temperature

saturated suction temperaturesaturated suction temperature

syst

em c

oolin

g ca

pacit

ysy

stem

coo

ling

capa

city


effect of cooling load and outdoor temperature

Subcooling Leaving Condenser

A highhigh highhigh 18 (10.0)18 (10.0) B lowlow highhigh 21 (11.7)21 (11.7)

C lowlow lowlow 13 (7.2) 13 (7.2) D highhigh lowlow 5 (2.8) 5 (2.8)

subcooling leaving subcooling leaving condenser*, °F (°C)condenser*, °F (°C)

cooling cooling loadload

outdooroutdoortemperaturetemperature

* This example system uses a TXV for the expansion device.* This example system uses a TXV for the expansion device.


Involve the Manufacturer

If provided, use refrigerant line sizes recommended by manufacturer

Air Conditioning Clinic TRG-TRC006-ENAir Conditioning Clinic TRG-TRC006-EN© American Standard Inc. 2002 evaporator capacity, tons (kW)evaporator capacity, tons (kW)

11(3.5)(3.5)

55(17.6)(17.6)

1010(35)(35)

5050(176)(176)

100100(352)(352)

200200(703)(703)

100100(0.5)(0.5)

5050(0.25)(0.25)

200200(1.0)(1.0)

500500(2.5)(2.5)

2020(70)(70)

22(7.0)(7.0)

5/16 (

8)

5/16 (

8)3/8

(10)

3/8 (1

0)

1/2 (1

2)

1/2 (1

2)

5/8 (1

5)

5/8 (1

5)

2 1/8

(54)

2 1/8

(54)

1 5/8

(42)

1 5/8

(42)

R-22R-22


1 1/8

(28)

1 1/8

(28)1,0001,000

(5.1)(5.1)

liquid line

Determine Refrigerant Velocityve

locit

y, fp

m (m

/s)

velo

city,

fpm

(m/s

)

7/8 (2

2)

7/8 (2

2)

1 3/8

(35)

1 3/8

(35)

1/4 (6

)1/4

(6)

3/4 (1

8)

3/4 (1

8)


liquid line


1/2 (12)1/2 (12) 850 (4.3)850 (4.3)5/8 (15)5/8 (15) 525 (2.7)525 (2.7)3/4 (18)3/4 (18) 350 (1.8)350 (1.8)7/8 (22)7/8 (22) 250 (1.3)250 (1.3)

1 1/8 (28)1 1/8 (28) 150 (0.8)150 (0.8)1 3/8 (35)1 3/8 (35) 100 (0.5)100 (0.5)


20 tons 20 tons (70.3 kW)(70.3 kW)


liquid line

Calculate Total Equivalent Length


condensercondenser

5/8 in.5/8 in.(15 mm)(15 mm)riserriser

5/8 in.5/8 in.(15 mm)(15 mm)

5/8 in.5/8 in.(15 mm)(15 mm)dropdrop

Air Conditioning Clinic TRG-TRC006-ENAir Conditioning Clinic TRG-TRC006-EN© American Standard Inc. 2002 evaporator capacity, tons (kW)evaporator capacity, tons (kW)

11(3.5)(3.5)

55(17.6)(17.6)

1010(35)(35)

5050(176)(176)

100100(352)(352)

200200(703)(703)

2020(70)(70)

22(7.0)(7.0)

R-22R-22


liquid line

Determine Pressure Droppr

essu

re d

rop,

psi/

100

ft (k

Pa/1

0 m

)pr

essu

re d

rop,

psi/

100

ft (k

Pa/1

0 m

)

1.01.0(2.3)(2.3)

2.02.0(4.6)(4.6)

5.05.0(11.5)(11.5)

10.010.0(23)(23)

20.020.0(46)(46)

50.050.0(115)(115)

5/8

(15)

5/8

(15)

7/8

(22)

7/8

(22)

1 1/

8 (2

8)1

1/8

(28)

1 3/

8 (3

5)1

3/8

(35)

1 5/

8 (4

2)1

5/8

(42)

1/2

(12)

1/2

(12)

3/4

(18)

3/4

(18)

2 1/

8 (5

4)2

1/8

(54)

3/8

(10)

3/8

(10)

5/16

(8)

5/16

(8)

1/4

(6)

1/4

(6)


liquid line


Filter-drier = 6 psi (41.4 kPa) Solenoid valve = 4 psi (27.6 kPa) Sight glass = 1 equivalent ft (0.3 m) Angle valve = 1 psi (6.9 kPa) Ball valve = 1 equivalent ft (0.3 m)

solenoidsolenoidvalvevalve


liquid line

Pressure Drop Due to Elevation


condensercondenser 15 ft 15 ft (4.6 m)(4.6 m)vertical rise vertical rise creates creates pressure droppressure drop

11 ft 11 ft (3.4 m)(3.4 m)vertical drop vertical drop creates creates pressure gainpressure gain


liquid line

Pressure Drop Due to Elevation

liquid temperature, °F (°C)liquid temperature, °F (°C)

pres

sure

dro

p/ne

t liq

uid

rise,

psi/

ft (k

Pa/m

)pr

essu

re d

rop/

net l

iqui

d ris

e, p

si/ft

(kPa

/m)

4040(4.4)(4.4)

6060(15.6)(15.6)

8080(26.7)(26.7)

100100(37.8)(37.8)

120120(48.9)(48.9)

140140(60.0)(60.0)

160160(71.1)(71.1)

0.4250.425(9.6)(9.6)

0.4500.450(10.2)(10.2)

0.4750.475(10.7)(10.7)

0.5000.500(11.3)(11.3)

0.5250.525(11.9)(11.9)

0.5500.550(12.4)(12.4)


liquid line

Calculate Loss of Subcooling

liquid temperature, °F (°C)liquid temperature, °F (°C)

loss

of s

ubco

olin

g, p

si/°F

(kPa

/°C)

loss

of s

ubco

olin

g, p

si/°F

(kPa

/°C)

4040(4.4)(4.4)

6060(15.6)(15.6)

8080(26.7)(26.7)

100100(37.8)(37.8)

120120(48.9)(48.9)

140140(60.0)(60.0)

160160(71.1)(71.1)

00(0)(0)

1.01.0(12.4)(12.4)

2.02.0(24.9)(24.9)

3.03.0(37.3)(37.3)

4.04.0(49.7)(49.7)

5.05.0(62.2)(62.2)


Subcooling Remaining at Expansion Device

15 (8.3)15 (8.3) -- 9.9 (5.5)9.9 (5.5) == 5.1 (2.8)5.1 (2.8)

leavingleavingcondensercondenser

subcooling, °F (°C)subcooling, °F (°C)

loss due toloss due toliquid lineliquid line

remaining at remaining at expansion expansion devicedevice


liquid line

Evaporator Coil Connections

TXVTXV





liquid line

Refrigerant Accessories

sightsightglassglass

TXVTXV

liquid lineliquid line

solenoid solenoid valvevalve

filter-drierfilter-drier


condensercondenser


Liquid Line Routing

route the horizontal leg below the riserroute the horizontal leg below the riser

evaporatorevaporatorcondensercondenser

condensercondenser



liquid line Other Considerations

Pitch horizontal sections to run alongside suction or discharge line

Insulate lines that are routed through very warm spaces

period five

Hot-Gas Bypass Line

Refrigerant Piping



hot-gas bypass line


Ensure that oil and refrigerant are not trapped in piping

Avoid excessive noise Proper routing is more critical than pipe

diameter


Hot-Gas Bypass to Evaporator Inlet


condensercondenser


hot-gas hot-gas bypass valvebypass valve

TXVTXV


suction linesuction line



Hot-Gas Bypass Valve Installation

condensercondenser



pitch back toward pitch back toward discharge linedischarge line

pilotpilotlineline



pitch awaypitch awayfrom hot-gasfrom hot-gasbypass valvebypass valve

hot-gas hot-gas bypass linebypass line


Hot-Gas Bypass Risers

hot-gashot-gasbypass riserbypass riser

suctionsuctionlinelinecompressorcompressor

drain legdrain leg

oil-returnoil-returnlineline

condensercondenser



hot-gas bypass line

Connection to Evaporator






TXVTXV


hot-gas bypass line

Connection to Evaporator





checkcheckvalvesvalves

TXVTXV


Hot-Gas Bypass to Suction Line


condensercondenser



suction linesuction line


liquid-injection liquid-injection valvevalve

TXVTXV


hot-gas bypass line

Connection to Suction Line

condensercondenser

compressorcompressor suction linesuction line



liquid-injection liquid-injection valvevalve



Hot-Gas Bypass Line Sizing

1/2 (12)1/2 (12) 6,700 (34.0)6,700 (34.0)5/8 (15)5/8 (15) 4,200 (21.3)4,200 (21.3)3/4 (18)3/4 (18) 2,825 (14.4)2,825 (14.4)7/8 (22)7/8 (22) 2,025 (10.3)2,025 (10.3)

1 1/8 (28)1 1/8 (28) 1,200 ( 6.1)1,200 ( 6.1)1 3/8 (35)1 3/8 (35) 775 ( 3.9)775 ( 3.9)


10 tons 10 tons (35.2 kW)(35.2 kW)


hot-gas bypass line Other Considerations

Insulate entire line to prevent refrigerant vapor from condensing

Minimize overall length of the line Install solenoid valve if system includes a

pump-down cycle

period six

Review

Refrigerant Piping



Review—Period One

Refrigerant Piping Requirements Return oil to compressor Ensure that only liquid refrigerant (no vapor) enters

the expansion device Minimize system capacity loss Minimize refrigerant charge

If provided, use line sizes recommended by the manufacturer


Review—Period Two

Suction line Ensure adequate velocity to return oil to the

compressor at all steps of unloading Avoid excessive noise Minimize system capacity and efficiency loss


Review—Period Three

Discharge line Ensure adequate velocity to return oil to the

compressor at all steps of unloading Avoid excessive noise Minimize efficiency loss


Review—Period Four

Liquid line Ensure that only liquid refrigerant enters the

expansion device Minimize refrigerant charge Avoid excessive noise and pipe erosion


Review—Period Five

Hot-gas bypass line Ensure that oil and refrigerant are not trapped in the

piping Avoid excessive noise Proper routing is more critical than pipe diameter

refrigerant piping a trane air conditioning clinic air conditioning clinic trg-trc006-en © american...

Documents

en american standard

manufacturer slide

refrigerant charge s

refrigerant line sizes

warm spaces liquid line

b c d slide

weight s

suction line requirements