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6.1
CFM Overview
The CFM (Cubic Feet per Minute) test is used to determine how much
air is being supplied to, and returned from, the conditioned space. Check
manufacturer's specifications and engineering designs to determine the tar-
get CFM for the space. The right amount of CFM will keep temperatures
comfortable, stable and enable the right amount of air changes per hour
throughout the space.
Measuring the CFM at the grilles is the best way to determine the amount
of air being delivered to or taken out of the conditioned space.
Every system requires the right amount of system CFM to efficiently de-
liver the correct amount of heating or cooling. This can be checked through
the Target Evap Exit Temp test or Check Me! switch position.
Measuring CFM can be a difficult task. Air coming out of the duct is
turbulent and the velocity widely varies across the grille. The Airflow test
on the HVAC Guide works with Fieldpiece airflow accessory head(s), AAV3,
employing a sophisticated algorithm to calculate a more accurate CFM.
The CFM test can measure up to 13 different grilles. On the INPUT
FORM the technician chooses either supply or return grille and enters in the
manufacturer's size and free area specifications or uses Fieldpiece algorithms
based on the size and type of grille. Always use the manufacturer's specifica-
tions when available since they will lead to the most accurate measurements
and diagnosis. The technician can take several readings per grille to ensure
an accurate average air velocity is obtained.
The HVAC Guide takes all the readings and calculates the CFM based on
average air velocity and size and type of grille. The OUTPUT form lists the
CFM for each grille, average, min, and max air velocity for each grille, total
return and total supply for each multiple grille test.
Clear
Input
Output
Sync
Recall
Enter
Save
MAX 30VDC
24VAC
CONNECT ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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 ONL
Y TO
ACCESSOR
Y HEADS!
HVAC Gu
ide
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
& Temper
ature
Accessor
y
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
Accessor
y
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 / 1mV
AC
400AAC MAX
!
ASX14
Air
Conditioner
Superhea
t and
Subcooling
AUTO
OFF
T/C
CAL
SET
ATM
STABLE
ON
LO BATT
Traverse example for a rectangular grille.
Measure CFM with the HG3 and AAV3.
Measure at several points on
the grille to get an accurate
airflow average. The HG3
automatiicaly averages all
readings.
