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2 8
2 9
3.1
Subcooling Overview
Subcooling is the temperature decrease below the saturation tempera-
ture (same as the condensing point) in the condenser. Too high, and refriger-
ant condenses too early in the condenser and ‘wastes’ most of the capacity of
the condenser. Too low, and a mixture of gas and liquid can be delivered to
the expansion valve, reducing efficiency.
In a properly working TXV/EXV system, the superheat is held constant.
This is why subcooling is the best way to obtain proper refrigerant charge for
a TXV/EXV system. If the air conditioner is in good working order and the
airflow is adjusted properly, comparing the actual and target subcooling will
tell you if refrigerant needs to be added or recovered (ensure the pressure
never exceeds the manufacturer's maximum overload pressure guidelines).
Make sure the TXV/EXV bulb is installed properly, there is proper re-
frigerant to obtain target subcooling, and there are no liquid line restrictions.
The
Actual SC
(subcooling) should be within ±3°F of the
Target SC
for correct refrigerant charge.
For Actual Subcooling, you need to measure liquid line pressure and liq-
uid line temperature. Target Subcooling is usually specified by the manufac-
turer and if not the HG3 uses conservative Target Subcooling tables.
Adding refrigerant increases your
Actual SC
. Recovering refrigerant
decreases your
Actual SC
. The amount of refrigerant necessary to add or
recover will vary based on the size of the system and the difference between
the Actual and Target SC.
Because everything is interdependent, changes in one part of the system
affect other parts of the system. For example, increasing airflow decreases the
subcooling, which may require adding refrigerant. After modifications, allow
15 minutes for the system to stabilize; and then retest.
Use the HG3, ASX14, and ATC1
to measure Actual Subcooling.
Refrigeration Cycle
EVAPORATOR
CONDENSER
THROTTLE
VALVE
COMPRESSOR
REFRIGERANT
FLOW
H
ig
h P
ress
ure Side
Low Press
ure
Sid
e
RETURN AIR
SUPPLY AIR
OUTDOOR AIR
HOT AIR
AA
V3
Air
Velocity
& T
emper
atur
e
Accessor
y
Head
ON
LCD
X100
LO BA
TT
READ
ENGLISH
ENG
LISH
METRIC
Ft/min
MPH
°F
M/s
KM/hr
°C
METRIC
AV
G
NORMAL
ATH4
AUT
O O
FF
ARH4
T1-T2
T2
T1
Function
T1
CAL
T2
CAL
AUT
O
OFF
°C
°F
T1
T2
Set meter to mVDC
range to display
temperature
directly
.
LO BA
TT
ON
Dual
Temper
atur
e
Head
OFF
ATH4
T1-T2
T2
T1
Function
T1
CAL
T2
CAL
AUT
O OFF
°C
Set meter to mVDC
range to display
temperature dir
ectly
.
LO BA
TT
ON
Dual
Temper
atur
e
Head
OFF
ASX14
ACH4
Sync
ET2W
Air
Conditioner
Superhea
t and
Subcooling
AUT
O
OFF
T/C
CAL
ATH4
T1-T2
T2
T1
Function
T1
CAL
T2
CAL
AUT
O OFF
°C
°F
T1
T2
Set meter to mVDC
range to display
temperatu
re directly
.
LO BA
TT
ON
Dual
Temper
atur
e
Head
OFF
SET
AT
M
ST
ABLE
ON
LO BA
TT
MAX 30VD
C
24VAC
CONNECT ONLY
TO
ACCESSORY
HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sync
ET2W
MAX 30VD
C
24VAC
CONNECT ONLY TO
ACCESSORY HEAD
!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sync
ET2W
MAX 30VD
C
24VAC
CONNECT ONLY TO
ACCESSORY HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sync
ET2W
MAX 30VDC
24VAC
CONNECT
ONLY TO
ACCESSORY HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sync
ET2W
MAX 30VDC
24VAC
CONNECT
ONLY TO
ACCESSO
RY HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sync
ET2W
MAX 30VDC
24VAC
CONNECT ONLY
TO
ACCESSORY
HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sync
ET2W
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY
HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sling
Psy
chr
ome
ter
Head
ON
AUT
O OFF
1%RH/mVDC
1°F/mVDC
1°C/mVDC
LO BA
TT
DEW
POINT
%RH
WET B
ULB
TEMP
°F
°C
ON
OFF
ACM3
AOX
2
Sync
ET2W
MAX 30VDC
24VAC
CONNECT
ONLY TO
ACCESSORY HE
AD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sync
ET2W
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY
HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sync
ET2W
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSOR
Y HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sync
ET2W
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSOR
Y HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sync
ET2W
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmi
tter
Sync
ET2W
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSOR
Y HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Sync
ET2W
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSOR
Y HEAD!
LO BA
TT
SEND
RECEIVE
ON
AC
DC
W
ireless
Tr
ansmitter
Carbon
Mono
xide
Accessor
y
Head
ON
Converts
1PPM CO
concentration
to 1mVDC
LO BA
TT
ON
OFF
AVERA
GE
NORMAL
AUT
O
OFF
ZERO
SET
CA
T .III
300V
400A
CLAM
P
AC Cur
rent
Clamp
1AAC / 1mV
AC
400AAC MAX
!
Combustion
Chec
k
%
O
%
CO
TEMP
ON
GAS
OIL
Lo Batt
°C °F
AUT
O
OFF
ST
ABLE
Fuel T
ype
2
2
T/C
CAL
ARH4
Sling
Psy
chr
omete
r
Head
ON
AUT
O OFF
1%RH/mVDC
1°F/mVDC
1°C/mVDC
LO BA
TT
DEW POINT
%RH
WET B
ULB
TEMP
°F
°C
ON
OFF
ATH4
T1-T2
T2
T1
Function
T1
CAL
T2
CAL
AUT
O OFF
°C
°F
T1
T2
Set meter to mVDC
range to dis
play
temperature dir
ectly
.
LO BA
TT
ON
Dual
Temper
atur
e
Head
OFF
AA
V3
Air V
elocity
&
Temper
atur
e
Accessor
y
Head
ON
LCD
X100
LO BA
TT
READ
ENGLISH
ENG
LISH
METRIC
Ft/min
MPH
°F
M/s
KM/hr
°C
METRIC
AV
G
NORMAL
AUT
O OFF
AOX
2
Combustion
Chec
k
%
O
%
CO
TEMP
ON
GAS
OIL
Lo Batt
°C °F
AUT
O
OFF
ST
ABLE
Fuel T
ype
2
2
T/C
CAL
ACM3
Carbon
Mono
xide
Accessor
y
Head
ON
Converts
1PPM CO
concentration
to 1mVDC
LO BA
TT
ON
OFF
AVERA
GE
NORMAL
AUT
O
OFF
ZERO
SET
ACH4
CA
T .III
300V
400A
CLAM
P
AC Cur
rent
Clamp
1AAC / 1mV
AC
400AAC MAX
!
ASX14
Air
Conditioner
Superhea
t and
Subcooling
AUT
O
OFF
T/C
CAL
SET
AT
M
ST
ABLE
ON
LO BA
TT
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Jacket
Charging
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Light
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Service
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Light
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Service
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONLY TO
ACCESSORY HEADS!
HVAC Guide
Fieldpiece HG3
SETUP
Target
Evaporator
Logger
Exit Temp
CFM
Display
Superheat
Subcooling
Combustion
CheckMe!
Data
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
Jacket
Charging
OUTPUT FORM
CO2: 6.3%
Excess O2:
76.8%
COAF: 103ppm
Net Temp:
82 ˙F
Standard Eff:
85%
Siegert Eff:
94%
Draft Press: 0.08IWC
INPUT FORM
Pressure is between
160psig and 220psig.
SL Pressure: ---.-psig
LL Pressure: ---.-psig
Difference: ---.-psig
Confirm Pressures
CustomerID: __JONES123
INPUT FORM
SH Table:Standard
Refrigerant:R-22
OD Dry Bulb:
85.4
˙F
Return WB:
61.0˙F
SL Pressure
:
---.-˙F
SL Temp:
--.-˙F
CustomerID:__JONES123
INPUT FORM
Into Evap
Return DB
: 72.1
˙F
Return WB:
64.5˙F
Out of Evap
Supply DB:
55.6˙F
CustomerID: __JONES123
Units:English
INPUT FORM
Span: 2hours
Per: 30seconds
SEY
SET ID:IndoorTemp
Measurement: 72.8
SET ID:CompAmps
Measurement: 17.2
INPUT FORM
ACV
CustomerID
:--JONES123
01/24/2000 04:20:22PM
OUTPUT FORM
CO2: 6.3%
Excess O2:
76.8%
COAF: 103ppm
Net Temp:
82 ˙F
Standard Eff:
85%
Siegert Eff:
94%
Draft Press: 0.08IWC
INPUT FORM W/O
Manufacturer’s Data
Refrigerant: R-22
LL Pressure: 220.3psig
LL Temp
:
91.1˙F
CustomerID:__JONES123
Units:English
12/31/2011 11:59:59PM
INPUT FORM W/O
Manufacturer’s Data
Refrigerant: R-22
LL Pressure: 220.3psig
LL Temp
:
91.1˙F
CustomerID:__JONES123
Units:English
12/31/2011 11:59:59PM
INPUT FORM
Into Evap
Return DB:
72.1
˙F
Return WB:
64.5˙F
Out of Evap
Supply DB
:
55.6˙F
CustomerID: __JONES123
Units:English
INPUT FORM
Refrigerant:R-410A
Constrict the
Charging Jacket until
the difference
between the SL
Pressure and LL
Pressure is between
INPUT FORM
SH Table:Standard
Refrigerant:R-22
OD Dry Bulb:
85.4
˙F
Return WB:
61.0˙F
SL Pressure
:
---.-˙F
SL Temp:
--.-˙F
CustomerID:__JONES123
INPUT FORM
Sys Type
:AC
Grant and Sys Info:
None
INDOOR UNIT
Meter Device:TXV/TEV
Return DB:
71.7˙F
Return WB:
60.8˙F
INPUT FORM
Sys Type
:AC
Grant and Sys Info:
None
INDOOR UNIT
Meter Device:TXV/TEV
Return DB:
71.7˙F
Return WB:
60.8˙F
Memory:
Com with PC
Erase a Single Test
Erase a Customer
Erase a Grant
Check Memory Status
Clear Data logs
Clear All Data
Memory:
Com with PC
Erase a Single Test
Erase a Customer
Erase a Grant
Check Memory Status
Clear Data logs
Clear All Data
INPUT FORM
SET ID:IndoorTemp
Measurement: 72.8
SET ID:CompAmps
Measurement: 17.2
Span: 2hours
Per: 30seconds
START
INPUT FORM
DCV
CustomerID
:--JONES123
01/24/2000 04:20:22PM
INPUT FORM
Grille 01
ID:LivingRm1
Flow:Supply
Manufacturer’s Data
Free Area in sqft:
00.421sqft
Velocity
: 212ft/min
INPUT FORM
Grille 01
ID:LivingRm1
Flow:Supply
Manufacturer’s Data
Free Area in sqft:
00.421sqft
Velocity
: 212ft/min
INPUT FORM
Into Evap
Return DB:
72.1
˙F
Return WB:
64.5˙F
Out of Evap
Supply DB:
55.6˙F
CustomerID
: __JONES123
Units:English
ARH4
Sling
Psychrometer
Head
ON
AUTO OFF
1%RH/mVDC
1°F/mVDC
1°C/mVDC
LO BATT
DEW POINT
%RH
WET BULB
TEMP
°F
°C
ON
OFF
ATH4
T1-T2
T2
T1
Function
T1
CAL
T2
CAL
AUTO OFF
°C
°F
T1
T2
Set meter to mVDC
range to display
temperature directly.
LO BATT
ON
Dual
Temperature
Head
OFF
ATH4
T1-T2
T2
T1
Function
T1
CAL
T2
CAL
AUTO OFF
°C
°F
T1
T2
Set meter to mVDC
range to display
temperature directly.
LO BATT
ON
Dual
Temperature
Head
OFF
AAV3
Air Velocity
& Temperature
Accessory
Head
ON
LCD
X100
LO BATT
READ
ENGLISH
ENGLISH METRIC
Ft/min
MPH
°F
M/s
KM/hr
°C
METRIC
AVG
NORMAL
AUTO OFF
AOX2
Combustion
Check
%
O
%
CO
TEMP
ON
GAS
OIL
Lo Batt
°C °F
AUTO
OFF
STABLE
Fuel Type
2
2
T/C
CAL
ACM3
Carbon
Monoxide
Accessory
Head
ON
Converts
1PPM CO
concentration
to 1mVDC
LO BATT
ON
OFF
AVERAGE
NORMAL
AUTO
OFF
ZERO
SET
ACH4
CAT.III
300V
400A
CLAMP
AC Current
Clamp
1AAC / 1mVAC
400AAC MAX
!
ASX14
Air
Conditioner
Superheat and
Subcooling
AUTO
OFF
T/C
CAL
SET
ATM
STABLE
ON
LO BATT
