Basic Refrigeration and Charging Procedures 3-04-2009

Technical Training

BASIC REFRIDGERATIONBASIC REFRIDGERATION

& &

CHARGING PROCEDURESCHARGING PROCEDURES

Instructor: Rick Drennan

1

BASIC REFRIGERATION

&

CHARGING PROCEDURES

Richard Drennan

FSR (Field Support Rep)

and Instructor for Global HVAC trainingservices Northern California and Northern Nevada

29 Years experience

Certifications: 6 Nate, EPA (608 & 609), Ruud Mod Furn, 410A, Tracpipe, Wardflex, York Millennium unit, Freus (water cooled cond. unit), Clarion’s UV self cleaning systems, Fujitsu

Mini Splits

Registered Proctor: Ruud, York, ICP (Carrier), Nate, ACCA, ESCO, HVAC Excellence, General Electric (ECM Total comfort system), Fujitsu & Tracpipe

Degrees: Electronics, Computer Programming and Computer Electronics

! AIRFLOW !

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CFM Calculation

• Proper air flow is the most import aspect of

any system.

• With improper airflow nothing at all will

work properly.

Real Life Charging Procedures

• Use Engineering Data for reference

• Humid climates demand it

• Full unit capacity depends on it

Measuring CFM

3

First Calculate FPM

� With a Magnahelic or Manometer, you can easily convert the pressure reading to FPM. Typical Static Pressure readings will be 1.5" to 4" with very large blowers maybe pushing 8" to 10". Onceyou have the pressure reading (Pv) from your gauge then calculate

� This formula calls for knowing the air density (D), but most use0.075 pounds per cubic foot as that is fairly close to normal room temperature air. If you test at high altitude, high humidity, or far from normal temperature, the Dwyer Instruments web site provides a detailed article on the use of pitot tubes and gives the conversion tables and factors to adjust to an appropriate density.

Pv/D1096.7x FPM =

Converting to CFM

• We calculate CFM by multiplying FPM by the area of the duct used in square feet. The formula for this is:

For Example: The area of a round duct is equal to the radius squared times pi, so a 6” diameter duct (3” radius) would be 3 x 3 = 9 in x 3.14159 = 28.27 square inches. That divided by 144 = 0.196 square feet.

Use the 0.196 number times the FPM number on the gauge when testing with 6" diameter duct to get CFM. The multiplier for 5”duct is 0.136. The multiplier for a 4” duct is .087.

R2)/144 x (Pi x FPM CFM =

Discharge temp. - Entering Temp. = TD

TD or ∆T = Temperature Difference

CFM = BTUH

1.08 X TD

HOW TO CALCULATE CFM USING THE

TEMPERATURE RISE METHOD

4

5

To To ““ClockClock”” the Gas Flow:the Gas Flow:

•Tu n up t rmos atTurn up thermostatso furnace runsso furnace runssteadilysteadily

•• Turn off pilots ofTurn off pilots oft r ap iancother appliances

Che k G s te C librationCheck Gas Meter CalibrationOne Revolution in SecondsOne Revolution in Seconds

Half

Foot

Two

Foot

Cubic

Feet

60

45 15

30

w Ca l e a w atHow to Calculate Gas Flow Rate

7575u. Ft Cu. Ft.

Per Hr.Per Hr.

Cu. Ft. Cu. Ft. Per Hr.Per Hr.

Cubic Feet Per Cubic Feet Per t nRevolution

3,600 3,600 ec rSec./Hr.

f r O Time for One n Sec.Revolution (Sec.)

xx==

0.50.5 3,600 3,600

2424

xx=

6

Using Gas Flow Rate to Using Gas Flow Rate to Calculate Heat Input RateCalculate Heat Input Rate

Gas Gas F ow Flow RateRate

Heat Heat n u Input RateRate

Gas Gas n Heating

RateRatexx ==

7575. F Cu. Ft.

er rPer Hr.

,778,750B uBtuh

10501050B Pe Btu Per C t.Cu. Ft.

xx ==

Check Temperature RiseCheck Temperature Rise

SupplySupply ReturnReturn

empera u R seTemperature Rise

Supply Air 135Supply Air 135°°F F

Return Air Return Air –– 7070°°FF

is 5Rise 65°FF

70135

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To Calculate CFMTo Calculate CFMTemperature Rise MethodTemperature Rise Method

CFM CFM

1.081.08 XX

XBTUBTU

utInput

T Temp. RiseRise

o b s o Combustion i e cyEfficiency

=

,01,010CFM

e t r s M t odTemperature Rise Method

1.08 1.08 X

XX7 078,750

BtuhBtuh

.90.90t Combustion

EfficiencyEfficiency

=

Example:Example:

6565em setemp rise

Calculating the Sensible output of

the Condensing Unit

• 1010 CFM

• 20 degree Delta T

• CFM x Delta T x 1.08 = BTUH Output

• 1010 x 20 x 1.08 = BTUH Output

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Calculating the Actual output of the

Condensing Unit

• 1010 CFM

• ?? degree Delta Heat

• CFM x Delta H x 4.5 = Actual BTUH Output

• 1010 x ?? x 4.5 = Actual BTUH Output

e p n Delta Heat on a properly operating system will be x . eapproximately 5.6 degrees

It works both ways

5.4/ HxBTUHCFM ∆=

5.4/ HxCFMBTUH ∆=

OR

Electric Heat output 3-Phase

414.373.1 xxVOLTSxAMPSBTUH =

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Now that Airflow is Correct

• We can begin by checking the refrigerant

charge.

• But FIRST, lets understand how the system

works.

REFRIGERANT PRESSURES, STATES

&CONDITIONS

C N NSECTION ONE

o n Load in f from

house

o u m iLoad out to ambient

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e f t c de f t c dHeat flows from hot to cold.Heat flows from hot to cold.

a r i e E a o t d er v p TEvaporator Side Terms

� v g e sEvaporating Pressure

� d s rLow Side Pressure

� u n r sSuction Pressure

� ure ureBack PressureBack Pressure

� C resCondensing Pressure

� H g High side pressure

�D e u eD e u eDischarge pressureDischarge pressure

� H u eHead pressure

n s r ee d T rC d n S sC d n S sCondenser Side TermsCondenser Side Terms

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CompressorCompressor

� u p ig r t r ly!Pumps refrigerant vapor only!

� D w Divides low and high side.

harg L neDischarge Line

� Connects the compressorto the condenser.

d eCondenser

� e t rom the i t.e at rom the i t.Rejects heat from the refrigerant.Rejects heat from the refrigerant.

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L q i L n u d i eLiquid Line

� p e nSupplies liquid refrigerant

o c n e e o h o c n e e o h from the condenser to the from the condenser to the

t et emetering device.metering device.

Metering Device M ng Dev cMetering Device

� Controls the flow of refrigerant.

� Divides low and high side.

Evaporatorrat rEvaporator

� Absorbs heat into the refrigerant.

� R e m ture o the Removes moisture from the air

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L nSuction Line Su i n Suction Line

� Returns superheated vapor from the evaporator to the compressor

e vReceivers

�An accessory added in the liquidline to store refrigerant for different loads placed on the system.

mu at rsAccumulators

�An accessory added in the Suctionline to store liquid refrigerant for different loads placed on the system to prevent liquid flood back to the compressor. Predominantly installed on Heat Pumps.

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CONDENSERCONDENSER

m e tTemperatures

e rePressures

States

� h ssuHigh Pressure� h e p r e High Temperature →� p e Superheated Vapor

� a PoSaturation Point →

( c n g a ( c n g a (vapor changing to a (vapor changing to a

l u a l u a liquid as heat is removed)liquid as heat is removed)

� e r A b n m e tNear Ambient Temperature� i r i r High Pressure High Pressure →→

� o uSubcooled Liquid

ON E R NCONDENSER INLET

⇓⇓⇓⇓

OU LE OUTLET ⇑⇑⇑⇑

E A OA RPO T RPO T REVAPORATOREVAPORATOR

T peTemperatures

P u es r sPressures

taS teStates

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p Evaporator ttinletinlet

⇓⇓⇓⇓ w P e r Low Pressure

← L w T m e tLow Temperaturet 0 iq idt 0 q idAbout 80% Liquid,About 80% Liquid, % V20% Vapor

S u t d r Saturated vapor →→ ( r (Temperature in

liq d which liquid is c o changing to a

va ovapor) ← L w P e re Low Pressure T mLow Temperature

t pSuperheated Vapor⇑⇑⇑⇑

v p orEvaporatorOutletOutlet

v cMetering Device

SUBCOOLING&

SUPERHEAT

(Compressors)

WSECTION TWO

S l pr Scroll Compressor

Op iOperation

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s ubcool s ubcool The concepts of subcooling and ng The p The concepts of subcooling and

per t e m t a ng t he t superheating are the two most

mpor a r t i s i t p e hat t important principles that the

v e e i m t c c t t service technician must service technician must

s a e t understand before attempting to t b f at e o understand before attempting to

e i y e i y systematically troubleshoot any s l r s s e hoot any systematically troubleshoot any

ac em . s shvac/r systems.

S bc lin n r a u o g u o g Subcooling and Superheating Subcooling and Superheating

c nSubcoolingiSubcooling he e is any heat removed s a is any heat removed

om om ur om om ur from the completely saturated c t t t s a from the completely saturated l t s a n q d hat r t n d i liquid that results in a drop in

t p r e s ns e t cha e e e b a em at ( l he temperature (sensible heat change) t efof r g r he e nt he e ntof the refrigerant.of the refrigerant.

o gS bc linSubcooling

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R- 222

210 psig = 105 ºF-95 ºF

Subcooling 10 ºF

e er i ub oolCondenser Subcooling

T O A TOTAL

U OOLIS GSUBCOOLING

210 psig = 105 ºF-90 ºF

Subcooling 15 ºF

u h t r a Superheat

p r h a h a Superheat is e t e n a d d o p t ly n a d d o p t ly is any heat added to completely t a e r s saturated vapor that results in a rise in r e va o t s i e r e va o t s i e saturated vapor that results in a rise in saturated vapor that results in a rise in

t re se ib t h .temperature (sensible heat change) of the gas.e p r e g ) f h e p r e g ) f h temperature (sensible heat change) of the gas.temperature (sensible heat change) of the gas.

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60 60 °FFFF = 76 psig = 45 °F

15 °FF n eComponent superheat

v p Evaporator Superheat t uper atEvaporator Superheat

l l Total or System m S Total or System

pe eu thhSuperheatSuperheat

u n n S c e ti l Suction line

r T p 80p 80Temperature 80Temperature 80°°FFF

i = 7 s g 7 s g 76 psig = 76 psig = 4554545°°FF

y a S u t te S p 35te S p 35System Superheat 35System Superheat 35°°FFF

METERINGDEVICES

HSECTION THREE

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a illaCapillaryCapillaryCapillary Tubeu eu eTubeTube o a c p n h r i x n h r i x n Thermostatic Expansion

VaaValve

u o a ic p n Ex n Ex n Automatic Expansion

vValvel el eValveValve e e Fixed ix ix Fixed –––– Pist n Pist nBore Pistono o Bore Piston

Ca il a TCa il a TCapillary Tubesl y ubes Capillary Tubes

� t e t eLow Cost deviceLow Cost device

� e g rHave no moving parts

� n u ed a d e n u ed a d e Can be used on a wide range Can be used on a wide range

o te p c sof obsolete applications

i Vt T r os a c x vT r os a c x vThermostatic Expansion ValveThermostatic Expansion Valve

�� s c s f c Most efficient i M Most efficient

�� ns a e ap n c M ta o v a M ta o v a Maintains a constant evaporator Maintains a constant evaporator

r eau ts psuperheat

�� H co p s H co p s Helps prevent compressor e p e m r s Helps prevent compressor

fl ifloodingoflooding

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s ypeTXV Types

� e i i gPressure Limiting

� P P rBalance PortBalance Port

� n l a zn l a zExternally equalizedExternally equalized

� te y lnt y lInternally EqualizedInternally Equalized

� c r te Electric operated

B l entTXV Bulb Placement

a ua z ap ati r a ua z ap atiTXV External Equalizer Tap LocationTXV External Equalizer Tap Location

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a c xp ns on om a l esi E i ai E i aAutomatic Expansion ValvesAutomatic Expansion Valves

�� a a va o a a va o Maintain a constant evaporator c n t t r c n t t r Maintain a constant evaporator

ssupressure

�� se o e s Used on small systems which U d n a ic U d n a ic Used on small systems which Used on small systems which a s a shave constant loadsh ve c n a t h ve c n a t have constant loads

ededFixedFixed-- i s i sBore Metering DevicesBore Metering Devices

�� o m n o d n i o m n o s d n ia Most common today on Residential st a R l st a R l Most common today on Residential 1 e e s 0 d w e s 0 d wsystems 10 seer and below

�� u p se d vic se d vicDual purpose device

k e e k e e Works as metering a device a g e a g eWorks as metering a device

r c lver c lveWorks as a check valvek a h k a h Works as a check valve

�� it a Critical chargeC c aC c aCritical chargeCritical charge

System CHARGE

SE I RSECTION FOUR

22

s ha g eIs The Refrigerant Charge Correct?

� A r fr g n y A r fr g n y f All refrigeration systems differ in the All refrigeration systems differ in the t e amount of charge they hold.

� r are i a There are guidelines, charts, and i es to o oi es to o otechniques to follow.techniques to follow.

� s m i o kns m i o knSystem design & layout must be knownSystem design & layout must be known

& what s e How long & what size s t s tis the line set?is the line set?

hatWhat’ e s the volume of i ithe filter drier?the filter drier?

C RG N TXV CHARGING RULES

1. C s t l1. C s t l1. Charge system under a high load1. Charge system under a high load

2 C r d pos2. Charge as a liquid when possible

d nt l d3. Throttle liquid blends into low side

Re d at com s 4. Record evaporator & compressor s e r ub ools e r ub oolsuperheat & Condenser subcoolingsuperheat & Condenser subcooling

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l e l e Capillary Tube Capillary Tube or or

O i i O i iFixed OrificeFixed Orifice

W i n he #1 Weigh in the correct charge

s y em e#3 Use system superheat method

ON IO G YSAIRCONDITIONING SYSTEMS

2 anuf c s har#2 Manufacture's charging charts

i e s or y m i e s or y m Requirements for system Requirements for system per t c gsuperheat charging

� P o to a wP or to a wProper evaporator air flowProper evaporator air flow

� c tes rAccurate remote bulb temperature tester

� A g e a A g e a Accurate gauge manifold setAccurate gauge manifold set

52 54 56 58 60 62 64 66 68 70 72 74 76

6 10 13 16 19 21 24 27 30 33 36 38 41

Condenser 7 10 13 16 19 21 24 27 30 33 36 39

Entering 6 9 12 15 18 21 24 28 31 34 37

Air 5 8 12 15 18 21 25 28 31 35

Temperature 8 11 15 19 22 26 30 33

5 9 13 16 20 24 27 31

6 10 14 18 22 25 29

8 12 15 20 23 27

To increase superheat remove refrigerant. To decrease superheat add refrigerant.

85ºF

90ºF

95ºF

100ºF

65ºF

70ºF

75ºF

80ºF

Indoor Wet-Bulb Air Temp rature

SYSTEM SUPERHEAT CHARGING CHART

� �

����

24

S pe e S pe eSystem Superheat S m u h tSystem Superheat

ti l ti l Suction line o i Suction line

p 60 e m e a Temperature 60 °°F

76 76 76 psig = p i = 76 psig = 45 45 °FFF

Sup 1 5 e h e h Superheat 15 Superheat 15 °°FFF

Alternate charging method

R22

Alternate charging method

R410A

25

Alternate charging method

Lineset length and Grade separation

SAMPLE

U TQUESTIONS

The high and low pressures in a refrigeration system are separated by:

a. The compressor.

b. The evaporator.

c. The metering device.

d. The filter drier.

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Subcooling can be defined as:

a. The cooling effect of an evaporator.

b. Any sensible heat removed from 100% saturated liquid.

c. The superheat that is removed at the top of the condenser.

d. The cooling of the compressor motor by returning refrigerants.

Always charge a TXV with a receiver and sightglass under a:

a. No load condition.

b. Low load condition.

c. High load condition.

d. None of the above.

Superheat is defined as:

a. The heat added the the saturated liquid.

b. Heat removed from the saturated liquid in the condenser.

c. The heat added to the saturated vapor exiting the evaporator.

d. The heat removed from the saturated vapor exiting the evaporator.

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Definition of EXPERIENCE

Something acquired after you need it…

Allow us to give it to you before you need it, to be

ready!

"Experience is a hard teacher because she

gives the test first, then the lesson afterwards."