Basics, psychrometrics, chart and graph

2. 2
In the early 1900’s, there was a young engineerIn the early 1900’s, there was a young engineer
Working For Buffalo Forge Company that receivedWorking For Buffalo Forge Company that received
aa 'flash of genius''flash of genius' while waiting for a train.while waiting for a train.
It was a foggy night and he was going over in hisIt was a foggy night and he was going over in his
mind the problem ofmind the problem of temperature and humiditytemperature and humidity
controlcontrol. By the time the train arrived, Carrier had. By the time the train arrived, Carrier had
an understanding of the relationship betweenan understanding of the relationship between
temperature, humidity and dew pointtemperature, humidity and dew point..
That young engineer was…That young engineer was…
……Willis H. CarrierWillis H. Carrier

3. 3
What Mr. Carrier’s 'flash ofWhat Mr. Carrier’s 'flash of
genius' that day came to begenius' that day came to be
known as Psychrometry...known as Psychrometry...
……the study ofthe study of airair andand
waterwater vaporvapor in mixture.in mixture.

4. COMFORT
• Comfort describes a delicate balance of pleasant feelings in
the body produced by its surrounding
• Comfort involves
– Temperature
– Humidity
– Air movement
– Air cleanliness
• The human body makes adjustments to comfort conditions
by its circulatory and respiratory systems

5. FOOD, ENERGY, AND THE BODY
• The body uses food to produce energy
• The body energy
– Some stored as fatty tissue
– Some leaves as waste
– Some leaves as heat
– Some is used to keep the body functioning

6. BODY TEMPERATURE
• Humans are comfortable when the heat is transferring to
the surroundings at the correct rate
• The body gives off and absorb heat by conduction,
convection and radiation
• Surroundings must be cooler than the body for the body to
be comfortable
• The body is close to being comfortable when it is at rest
and in surroundings of 75 F and 50% humidity with slight
air movement
• Comfort conditions in winter and in summer are different

7. AMBIENTAMBIENT
TEMPERATURE 75°F atTEMPERATURE 75°F at
50% HUMIDITY50% HUMIDITY
BODY TEMPERATUREBODY TEMPERATURE
OF 98.6°FOF 98.6°F
Heat travels from theHeat travels from the
body to the ambientbody to the ambient
airair

8. Outside ambientOutside ambient
temperaturetemperature
100°F100°F
The body cannot give up heatThe body cannot give up heat
readilyreadily

9. THE COMFORT CHART
• Can be used to compare one comfort
situation or condition with another
• Shows the different combinations of
temperature and humidity for summer and
winter
• The closer the plot falls to the middle of the
chart, the more people would be comfortable
• Different charts for summer and winter
conditions

10. 10
PsychrometricPsychrometric
Chart...Chart...
……graphically showsgraphically shows
thethe PropertiesProperties of Air.of Air.

11. 11
PsychrometricPsychrometric
Chart used...Chart used...
……toto modelmodel conditionsconditions
inside buildings byinside buildings by
system designers.system designers.

12. 12
PsychrometricPsychrometric
Chart used...Chart used...
……toto monitormonitor conditionsconditions inin
commercial refrigerationcommercial refrigeration
plants and manufacturingplants and manufacturing
environments.environments.

13. 13
PsychrometricPsychrometric
Chart used...Chart used...
……toto evaluateevaluate problemsproblems
in air conditionedin air conditioned
environments.environments.

14. 14
INSTEP
INSTEP
SOLESOLE
HH
EE
EE
LL
Structure…Structure…
INSTEP
INSTEP

15. 15
11
22
33
44
55
66
77
Seven Properties of AirSeven Properties of Air

16. 16
Seven Properties of Air...Seven Properties of Air...
Dry bulb temperature …Dry bulb temperature …taken withtaken with
aa standardstandard thermometerthermometer..
SOLESOLE 808000
F DBF DB
00
FF

17. Dry Bulb Temperature
• Measured with a dry-bulb thermometer
• Measures the level of heat intensity of a
substance
• Used to measure and calculate sensible heat
and changes in sensible heat levels
• Does not take into account the latent heat
aspect
• Room thermostats measure the level of heat
intensity in an occupied space

18. DRY-BULB TEMPERATURE SCALEDRY-BULB TEMPERATURE SCALE
DRY-BULB TEMPERATUREDRY-BULB TEMPERATURE
As we move up and down, theAs we move up and down, the
dry bulb temperature does notdry bulb temperature does not
changechange
As we move from left toAs we move from left to
right, the dry bulbright, the dry bulb
temperature increasestemperature increases
As we move from rightAs we move from right
to left, the dry bulbto left, the dry bulb
temperature decreasestemperature decreases

19. 19
PROPERTY
OF AIR
SYMBOL EXPRESSED
BY
SCALE
LOCATION
LINE
DRAWN
DRY BULB
TEMP DB 0
F
SOLE
BOTTOM
STRAIGHT
UP

20. 20
Seven Properties of Air...Seven Properties of Air...
2.2. WetWet BulbBulb TemperatureTemperature
……taken with a thermometertaken with a thermometer
with awith a wettedwetted wickwick..
InstepInstep
666600
FF WBWB
SLINGSLING
PSYCHROMETERPSYCHROMETER

21. Wet Bulb Temperature
• Measured with a wet-bulb thermometer
• Temperature reading is affected by the
moisture content of the air
• Takes the latent heat aspect into account
• Used in conjunction with the dry-bulb
temperature reading to obtain relative
humidity readings and other pertinent
information regarding an air sample

22. WET-BULB TEMPERATURE SCALEWET-BULB TEMPERATURE SCALE
As we move up and down along aAs we move up and down along a
wet-bulb temperature line, thewet-bulb temperature line, the
wet bulb temperature does notwet bulb temperature does not
changechange
W
ET
BULB
TEMPERATURE
W
ET
BULB
TEMPERATURE
The red arrow indicates anThe red arrow indicates an
increase in the wet bulbincrease in the wet bulb
temperature readingtemperature reading
The blue arrowThe blue arrow
indicates a decreaseindicates a decrease
in the wet bulbin the wet bulb
temperature readingtemperature reading

23. DRY-BULB TEMPERATUREDRY-BULB TEMPERATURE
W
ET
BU
LB
TEM
PER
ATU
R
E
W
ET
BU
LB
TEM
PER
ATU
R
E
WET-BULB, DRY-BULB COMBOWET-BULB, DRY-BULB COMBO

24. 24
PROPERTY
OF AIR
SYMBOL EXPRESSED
BY
SCALE
LOCATION
LINE
DRAWN
DRY BULB
TEMP DB 0
F
SOLE
BOTTOM
STRAIGHT
UP
WET BULB
TEMP WB 0
F
INSTEP SLANTED

25. 25
Seven Properties of Air...Seven Properties of Air...
3.3.Dew Point TemperatureDew Point Temperature
……temperature at whichtemperature at which
moisture condenses onmoisture condenses on
a surface.a surface.

26. 26
PROPERTY
OF AIR
SYMBOL EXPRESSED
BY
SCALE
LOCATION
LINE
DRAWN
DRY BULB
TEMP DB 0
F
SOLE
BOTTOM
STRAIGHT
UP
WET BULB
TEMP WB 0
F
INSTEP SLANTED
DEW POINT
TEMP DP 0
F
INSTEP
HORIZONTAL
TO LEFT

27. DEW POINT TEMPERATURE
• The temperature at which the moisture in the air
begins to condense out of the air
• The temperature at which water forms on objects
from the air is called the dew point temperature of
the air
• The evaporator in an air conditioning or
refrigeration system operates below the dew point
temperature, so, as air comes in contact with the
coil, moisture begins to condense out of the air

28. Glass of ice water (45°F)Glass of ice water (45°F)
Dew pointDew point
temperature of thetemperature of the
surrounding air 55°Fsurrounding air 55°F
Droplets of moistureDroplets of moisture
begin to form on thebegin to form on the
surface of the glasssurface of the glass

29. 29
Seven Properties of Air...Seven Properties of Air...
4.4. SpecificSpecific HumidityHumidity
AbsoluteAbsolute HumidityHumidity oror HumidityHumidity
RatioRatio
……amount of water vapor inamount of water vapor in
dry air. Measured indry air. Measured in grainsgrains
perper poundpound of dry air.of dry air.
77 gr/lb77 gr/lb
HeelHeel

30. 30
OF AIR BY LOCATION DRAWN
DRY BULB
TEMP DB 0
F
SOLE
BOTTOM
STRAIGHT
UP
WET BULB
TEMP WB 0
F
INSTEP SLANTED
DEW POINT
TEMP DP 0
F
INSTEP
HORIZONTAL
TO LEFT
SPECIFIC
HUMIDITY W GR/LB
HEEL
RIGHT VERT
HORIZONTAL
TO RIGHT

31. ---- HUMIDITY ----
ABSOLUTELY RELATIVE
• There are two types of humidity
– ABSOLUTE
– RELATIVE
• “AH” and “RH” are not the same
• Cannot be used interchangeably
• All humidities are not created equal

32. ABSOLUTE HUMIDITY
• Amount of moisture present in an air
sample
• Measured in grains per pound of air
• 7,000 grains of moisture = 1 pound
1 POUND1 POUND
6060
GRAINSGRAINS

33. The moisture scale on the
right-hand side of the chart
provides information regarding
the absolute humidity of an air
sample

34. MOISTURE CONTENT SCALEMOISTURE CONTENT SCALE
As we move from side toAs we move from side to
side, the moisture contentside, the moisture content
does not changedoes not change
As we move up, the moistureAs we move up, the moisture
content increasescontent increases
As we move down, theAs we move down, the
moisture content decreasesmoisture content decreases
MOISTURECONTENTMOISTURECONTENT
(BTU/LB(BTU/LBAIRAIR))

35. 35
5.5. RelativeRelative HumidityHumidity
Seven Properties of Air...Seven Properties of Air...
Curved LinesCurved Lines
Saturation PointSaturation Point
Curve = 100% RHCurve = 100% RH
……the amount of moisturethe amount of moisture
vapor the air is holdingvapor the air is holding
compared to what it couldcompared to what it could
hold at the same DBhold at the same DB
temperature.temperature.

36. RELATIVE HUMIDITY
• Amount of moisture present in an air sample
relative to the maximum moisture capacity of
the air sample
• Expressed as a percentage
• Can be described as the absolute humidity
divided by the maximum moisture-holding
capacity of the air

37. RELATIVE HUMIDITY
Example #1Example #1
HOW FULL IS THE PARKINGHOW FULL IS THE PARKING
LOT?LOT?
% FULL% FULL ==
# of CARS# of CARS
# of SPACES# of SPACES
XX 100%100%% FULL% FULL ==
10 CARS10 CARS
20 SPACES20 SPACES
XX 100%100%% FULL = 0.5 X 100%% FULL = 0.5 X 100%

38. RELATIVE HUMIDITY
Example #2Example #2

39. RELATIVE HUMIDITY
Example #3Example #3
6060
GRAINSGRAINS
If capacity is 120 grains, then the relative humidityIf capacity is 120 grains, then the relative humidity
will be:will be:
RH = (60 grainsRH = (60 grains ÷ 120 grains) x 100% =÷ 120 grains) x 100% =
50%50%

40. RELATIVE HUMIDITY SCALERELATIVE HUMIDITY SCALE
As we move along a relativeAs we move along a relative
humidity line, the relativehumidity line, the relative
humidity remains the samehumidity remains the same
As we move up, the relativeAs we move up, the relative
humidity increaseshumidity increases
As we move down, theAs we move down, the
relative humidity decreasesrelative humidity decreases

41. 41
PROPERTY
OF AIR
SYMBOL EXPRESSED
BY
SCALE
LOCATION
LINE
DRAWN
DRY BULB
TEMP DB 0
F
SOLE
BOTTOM
STRAIGHT
UP
WET BULB
TEMP WB 0
F
INSTEP SLANTED
SPECIFIC
HUMIDITY W GR/LB
HEEL
RIGHT VERT
HORIZONTAL
TO RIGHT
DEW POINT
TEMP DP 0
F
INSTEP
HORIZONTAL
TO LEFT
RELATIVE
HUMIDITY RH %RH CURVED CURVED

42. 42
Seven Properties of Air...Seven Properties of Air...
6.6. SpecificSpecific VolumeVolume
- Steeply slanted lines- Steeply slanted lines
- Expressed in Cubic Feet- Expressed in Cubic Feet
per Pound ( ftper Pound ( ft33
/lb )/lb )
- Space that one pound of- Space that one pound of
dry air takes updry air takes up

43. SPECIFIC VOLUME & DENSITY
• Specific volume and density are reciprocals
of each other
• Density = lb/ft3
• Specific volume = ft3
/lb
• Density x Specific Volume = 1
• Specific volume can be determined from
the psychrometric chart, density must be
calculated

44. LINES OF SPECIFIC VOLUMELINES OF SPECIFIC VOLUME
ftft33/lb/lb
As we move along a line ofAs we move along a line of
constant specific volume, theconstant specific volume, the
specific volume remainsspecific volume remains
unchangedunchanged
As we move to the right, theAs we move to the right, the
specific volume increasesspecific volume increases
As we move to the left,As we move to the left,
the specific volumethe specific volume
decreasesdecreases

45. 45
PROPERTY
OF AIR
SYMBOL EXPRESSED
BY
SCALE
LOCATION
LINE
DRAWN
DRY BULB
TEMP DB 0
F
SOLE
BOTTOM
STRAIGHT
UP
WET BULB
TEMP WB 0
F
INSTEP SLANTED
SPECIFIC
HUMIDITY W GR/LB
HEEL
RIGHT VERT
HORIZONTAL
TO RIGHT
DEW POINT
TEMP DP 0
F
INSTEP
HORIZONTAL
TO LEFT
RELATIVE
HUMIDITY RH %RH CURVED CURVED
SPECIFIC
VOLUME V FT3
/LB
STEEPLY
SLANTED
STEEPLY
SLANTED

46. 46
Seven Properties of Air...Seven Properties of Air...
7.7. EnthalpyEnthalpy
-- TotalTotal amount of heatamount of heat
energy (energy (sensiblesensible andand
latentlatent) in one pound) in one pound
of air.of air.

47. The lines that represent
constant wet-bulb temperature
also represent the enthalpy of
the air

48. ENTHALPY SCALEENTHALPY SCALE
As we move up and downAs we move up and down
along an enthalpy line, thealong an enthalpy line, the
enthalpy does not changeenthalpy does not change
The red arrowThe red arrow
indicates an increaseindicates an increase
in enthalpyin enthalpy
The blue arrowThe blue arrow
indicates a decreaseindicates a decrease
in enthalpyin enthalpy

49. 49
PROPERTY
OF AIR
SYMBOL EXPRESSED
BY
SCALE
LOCATION
LINE
DRAWN
DRY BULB
TEMP DB 0
F
SOLE
BOTTOM
STRAIGHT
UP
WET BULB
TEMP WB 0
F
INSTEP SLANTED
SPECIFIC
HUMIDITY W GR/LB
HEEL
RIGHT VERT
HORIZONTAL
TO RIGHT
DEW POINT
TEMP DP 0
F
INSTEP
HORIZONTAL
TO LEFT
RELATIVE
HUMIDITY RH %RH CURVED CURVED
SPECIFIC
VOLUME V FT3
/LB
STEEPLY
SLANTED
STEEPLY
SLANTED
ENTHALPY H BTU/LB ABOVE
INSTEP
EXTENSION
OF WB LINE

50. 50
XX
Making a Sling Psychrometer for readingMaking a Sling Psychrometer for reading
WB:WB: Need: 1 ea. Athletic Shoe LaceNeed: 1 ea. Athletic Shoe Lace
Cut Shoe LaceCut Shoe Lace
Poke Pocket Thermometer into long piece of Shoe LacePoke Pocket Thermometer into long piece of Shoe Lace
Short piece taped or rubber-banded to ThermometerShort piece taped or rubber-banded to Thermometer
To use: Wet short end and sling whileTo use: Wet short end and sling while
holding on to long end.holding on to long end.

52. RETURNRETURN
AIRAIR
SUPPLYSUPPLY
AIRAIR
Return Air: 75Return Air: 75ºFDB,ºFDB,
50% r.h.50% r.h.
Supply Air: 55Supply Air: 55ºFDB,ºFDB,
90% r.h.90% r.h.
Airflow: 1200 cfmAirflow: 1200 cfm

53. RETURNRETURN
AIRAIR
SUPPLYSUPPLY
AIRAIR
Return Air: 75Return Air: 75ºFDB,ºFDB,
50% r.h.50% r.h.Supply Air: 55ºFDB, 90% r.h.
Airflow: 1200 cfmAirflow: 1200 cfm
5555ºFºF 75ºF75ºF
ΔT = Return Air Temp – Supply AirΔT = Return Air Temp – Supply Air
TempTemp
ΔT = 75ºF - 55ºF = 20ºFΔT = 75ºF - 55ºF = 20ºF
6464
grains/lbgrains/lb
6060
grains/lbgrains/lb
h = 28.1 btu/lbh = 28.1 btu/lbAIRAIR
h = 21.6 Btu/lbh = 21.6 Btu/lbAIRAIR
ΔW = Return grains/lbΔW = Return grains/lbAIRAIR – Supply– Supply
grains/lbgrains/lbAIRAIR
ΔW = 64 Grains – 60 Grains = 4 grains/lbΔW = 64 Grains – 60 Grains = 4 grains/lbAIRAIR
Δh = Return btu/lbΔh = Return btu/lbAIRAIR – Supply btu/lb– Supply btu/lbAIRAIR
Δh = 28.1 btu/lbΔh = 28.1 btu/lbAIRAIR - 21.6 btu/lb- 21.6 btu/lbAIRAIR = 6.5= 6.5
btu/lbbtu/lbAIRAIR

54. 54

55. 55
RASA
Blower Section
HeatHeat
SectionSection
Transition
EvapEvap CoilCoil
Air Conditioning Processes...
Psychrometric
changes take
place between
RA and SA
Return AirReturn Air
PlenumPlenum
Supply AirSupply Air
PlenumPlenum

56. 56
Initial Point
(Return Air reading)
Process Line moves
horizonally to right
∆T
0∆GR
Heating only SensibleSensible
changechange

57. 57
Process Line moves
horizonally to left
∆T
0∆GR
Cooling only SensibleSensible
changechange

58. 58
Process Line moves
straight up
0∆T
∆GR
Humidifying only
LatentLatent
changechange

59. 59
Process Line moves
straight down
0∆T
∆GR
Dehumidifying only
LatentLatent
changechange

60. 60
Other AC Processes...
Heating &Heating &
HumidifyingHumidifying
Heating &Heating &
DehumidifyingDehumidifying
Cooling &Cooling &
HumidifyingHumidifying
Cooling &Cooling &
DehumidifyingDehumidifying
Sensible and Latent changeSensible and Latent change

61. Prof. Koldenhott's FUNdamentals
of Cocktailmetrics
61
∆T
∆GR
∆H
Process Line
Process Line
800
F DB600
F DB
50% RH
80% RH
What we need
for evaluating
AC Processes...
RARA
SASA

62. AIR FORMULAE
QL = 0.68 x Cfm x ΔW
QQTT = Q= QSS + Q+ QLL
QQTT = 4.5 x Cfm X= 4.5 x Cfm X ΔhΔh
QQss = 1.1 x Cfm X= 1.1 x Cfm X ΔTΔT

63. 63
Air Side Equations
Sensible Load:
Qs = 1.1 X CFM X ∆T
A constant basedA constant based
on the Density ofon the Density of
Air and a timeAir and a time
conversion factorconversion factor
Determined fromDetermined from
the Condensingthe Condensing
Unit model numberUnit model number
QQSS is expressed in BTUHis expressed in BTUH

64. 64
Air Side Equations
Latent Load:
QL = .68 X CFM X ∆GR
QQLL is expressed in BTUHis expressed in BTUH
A constant…A constant…
including a timeincluding a time
conversion factorconversion factor
Same as that usedSame as that used
for Qfor QSS

65. 65
Air Side Equations
Total Load:
QT = 4.45 X CFM X ∆H
A constant…A constant…
including a timeincluding a time
conversion factorconversion factor
Same as that usedSame as that used
for Qfor QSS
QQTT is expressed in BTUHis expressed in BTUH

66. 66

67. 67
Sensible HeatSensible Heat
Ratio…Ratio…
……the ratio of Sensiblethe ratio of Sensible
Load (QLoad (QSS) to) to
Total Load (QTotal Load (QTT))
LATENT SENSIBLE

68. 68
Sensible Heat
Ratio…
SHR =
QS
QT

69. 69
Sensible Heat Ratio…
SHR =
29,060 btuh
36,325 btuh
Example:
=
.80 SHR

70. Prof. Koldenhott's FUNdamentals
of Cocktailmetrics
70
Sensible Heat Ratio…Sensible Heat Ratio…
The way Engineers Plot SHR
on the Psychrometric Chart
PermanentPermanent
Index PointIndex Point
.80 SHR.80 SHR
.
Note: Any Process LineNote: Any Process Line
parallelparallel to this line willto this line will
maintain the SHRmaintain the SHR

71. 71
HHss
HHLL
……SensibleSensible
change inchange in
EnthalpyEnthalpy
……LatentLatent
change inchange in
EnthalpyEnthalpy
∆T
Sensible change…Sensible change…
∆GR
LatentLatent
changechange……

72. RETURN AIRRETURN AIR SUPPLY AIRSUPPLY AIR
Water Vapor at 75ºFWater Vapor at 75ºF
Water atWater at
50ºF50ºF

73. TOTAL HEAT
• The capacity of a heating and cooling unit
may be field checked with the total heat
feature of the psychrometric chart
• Total heat = sensible heat + latent heat
• Sensible heat formula: Qs = 1.08 x cfm x ∆T
• Total heat formula: Qt = 4.5 x cfm x total heat
difference
• CFM formula: ______Qs______
1.08 x ∆T

74. SUMMARY
• Comfort is affected by air movement, humidity,
air cleanliness and temperature
• Humans are considered to be comfortable
when heat is transferred from the body to its
surroundings at the proper rate
• The body is close to being comfortable when it
is at rest and in surroundings of 75°F and 50%
humidity with slight air movement
• The comfort chart is used to compare one
comfort situation or condition with another

75. SUMMARY
• Psychrometrics is the study of air and its
properties
• Density indicates how many pounds one cubic
foot of a substance weighs
• Specific volume is the reciprocal of density
• Moisture in air is referred to as humidity
• Dry bulb temperature is the sensible heat level
of air
• Wet bulb temperatures take the moisture
content of the air into account

76. SUMMARY
• The dew point temperature is the point at
which moisture in the air begins to
condense out of the air
• The psychrometric chart provides a
graphical representation of an air sample
as well as a means to calculate other
properties of the air
• Total heat = sensible heat + latent heat

77. LAW OF THE TEE FOR MIXED AIR
AIRAIR
HANDLERHANDLER
OUTSIDE AIROUTSIDE AIR
RETURN AIRRETURN AIR
MIXEDMIXED
AIRAIR

78. LAW OF THE TEE FOR MIXED AIRLAW OF THE TEE FOR MIXED AIR
PERCENTAGE OF RETURN AIR +PERCENTAGE OF RETURN AIR +
PERCENTAGE OF OUTSIDE AIRPERCENTAGE OF OUTSIDE AIR
100% of MIXED AIR100% of MIXED AIR
OUTSIDEOUTSIDE
RETURNRETURN

79. LAW OF THE TEE FOR MIXED AIRLAW OF THE TEE FOR MIXED AIR
SAMPLE PROBLEMSAMPLE PROBLEM
AIR CONDITIONS:AIR CONDITIONS: RETURN AIR (80%): 75RETURN AIR (80%): 75ºFDB, 50%RHºFDB, 50%RH
OUTSIDE AIR (20%): 85ºFDB, 60%RHOUTSIDE AIR (20%): 85ºFDB, 60%RH
MIXED AIR = 80% RETURN AIR + 20% OUTSIDE AIRMIXED AIR = 80% RETURN AIR + 20% OUTSIDE AIR
MIXED AIR = (.80) RETURN AIR + (.20) OUTSIDE AIRMIXED AIR = (.80) RETURN AIR + (.20) OUTSIDE AIR
MIXED AIR = (.80) (75MIXED AIR = (.80) (75ºFDB, 50%RH)ºFDB, 50%RH) + (.20) (85ºFDB, 60%RH)+ (.20) (85ºFDB, 60%RH)
MIXED AIR = 60MIXED AIR = 60ºFDB, 40%RHºFDB, 40%RH + 17ºFDB, 12%RH+ 17ºFDB, 12%RH
MIXED AIR = 77MIXED AIR = 77ºFDB, 52%RHºFDB, 52%RH

80. Return Air: 75Return Air: 75ºFDB,ºFDB,
50% r.h.50% r.h.
Outside Air: 85Outside Air: 85ºFDB,ºFDB,
60% r.h.60% r.h.
Mixed Air: 77Mixed Air: 77ºFDB, 52%ºFDB, 52%
r.h.r.h.
RETURN AIRRETURN AIR
OUTSIDE AIROUTSIDE AIR
MIXED AIRMIXED AIR
SUPPLY AIRSUPPLY AIR