Supply Air Drive Adjustment
CAUTION
Before making any blower speed changes review
the installation for any installation errors, leaks or
undesirable systems effects that can result in loss of
airflow.
Even small changes in blower speed can result in
substantial changes in static pressure and BHP. BHP
and AMP draw of the blower motor will increase
by the cube of the blower speed. Static pressure
will increase by the square of the blower speed.
Only qualified personnel should make blower speed
changes, strictly adhering to the fan laws.
At unit start-up, the measured CFM may be higher
or lower than the required CFM. To achieve the
required CFM, the speed of the drive may have
adjusted by changing the datum diameter (DD) of
the variable pitch motor sheave as described below:
Use the following tables and the DD calculated per
the above equation to adjust the motor variable
pitch sheave.
EXAMPLE NEW DATUM DIAMETER
A 4 ton unit was selected to deliver 1,600 CFM with a
1VL34 motor sheave, but the unit is delivering 1,350
CFM. The variable pitch motor sheave is set at 4
turns open.
Use the equation to determine the required DD for
the new motor sheave,
Use Table 37 to locate the DD nearest to 2.48 in.
Close the sheave to 2 turn open.
EXAMPLE NEW BHP
= (Speed increase)
3
• Original BHP = New BHP
= (Speed increase)
3
• BHP at 1,350 CFM
EXAMPLE NEW MOTOR AMPS
= (Speed increase)
3
• Original Amps = New Amps
= (Speed increase)
3
• Amps at 1,350 CFM
Table 37: Motor Sheave Datum Diameters
1VL34
1VL44
Turns Open
Datum Diameter
Turns Open
Datum Diameter
0
2.9
0
3.8
1/2
2.8
1/2
3.7
1
2.7
1
3.6
1-1/2
2.6
1-1/2
3.5
2
2.5
2
3.4
2-1/2
2.4
2-1/2
3.3
3
2.3
3
3.2
3-1/2
2.2
3-1/2
3.1
4
2.1
4
3.0
4-1/2
2.0
4-1/2
2.9
5
1.9
5
2.8
5-1/2
-
5-1/2
-
6
-
6
-
CAUTION
Belt drive blower systems MUST be adjusted to
the specific static and CFM requirements for the
application. The Belt drive blowers are NOT set at the
factory for any specific static or CFM. Adjustments of
the blower speed and belt tension are REQUIRED.
Verify proper sheave alignment; tighten blower pulley
and motor sheave set screws after these adjustments.
Re-checking set screws and belt tension after 10-12
hrs. run time is recommended.
INSTALLATION MANUAL ZQ SERIES 3 - 5 ton 60 Hertz R-410A
52
Johnson Controls Ducted Systems
Содержание ZQ Series
Страница 2: ...2 INSTALLATION MANUAL ZQ SERIES 3 5 ton 60 Hertz R 410A Johnson Controls Ducted Systems ...
Страница 8: ...Nomenclature INSTALLATION MANUAL ZQ SERIES 3 5 ton 60 Hertz R 410A 8 Johnson Controls Ducted Systems ...
Страница 87: ...Start Up Sheet INSTALLATION MANUAL ZQ SERIES 3 5 ton 60 Hertz R 410A 87 Johnson Controls Ducted Systems ...
Страница 88: ... INSTALLATION MANUAL ZQ SERIES 3 5 ton 60 Hertz R 410A 88 Johnson Controls Ducted Systems ...
Страница 89: ... INSTALLATION MANUAL ZQ SERIES 3 5 ton 60 Hertz R 410A 89 Johnson Controls Ducted Systems ...
Страница 90: ... INSTALLATION MANUAL ZQ SERIES 3 5 ton 60 Hertz R 410A 90 Johnson Controls Ducted Systems ...
Страница 91: ... INSTALLATION MANUAL ZQ SERIES 3 5 ton 60 Hertz R 410A 91 Johnson Controls Ducted Systems ...