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Step 14 — Check Belt Tension
Measure the belt span length as shown in Fig. 53. Calculate the re-
quired deflection by multiplying the belt span length by
example, if the belt span length is 32 inches: 32 x
deflection.
BELT FORCE — DEFLECTION METHOD
Check the belt tension with a spring-force belt force deflection
gauge (available from drive belt manufacturer).
1. Place a straightedge along the belt between the two pul-
leys. Measure the distance between the motor shaft and
the blower shaft.
2. Set the tension gauge to the desired tension (see Table 1 in
Fig. 53). Place the large O-ring at that point.
3. Press the tension checker downward on the belt until the
large O-ring is at the bottom of the straightedge.
4. Adjust the belt tension as needed.
Adjust belt tension by loosing the motor mounting plate front bolts
and rear bolt (see Fig. 54) and slide the plate towards the fan (to
reduce tension) or away from the fan (to increase tension). Ensure
the blower shaft and motor shaft are parallel to each other (pulleys
aligned). Tighten all bolts securely when finished.
BELT TENSION METHOD
Requires belt tension gauge that measures tension in belt in units
of lbs force.
BELT DEFLECTION FORCE (LBS)
BELT
SMALLEST
UNNOTCHED
CROSS
SHEAVE
SECTION
DIAMETER
USED
3.0-3.6
A, AX
3.8-4.8
5.0-7.0
3.4-4.2
B, BX
4.4-5.6
5.8-8.6
Table 1
BELT CONDITION
TENSION FORCE IN BELT (LBS)
NEW
USED
Table 2
Fig. 53 — V-Belt Force Label
/
=
1
64
NOTCHED
BELTS
BELTS
NEW
USED
NEW
3.7
5.5
4.1
4.5
6.8
5.0
5.4
8.0
5.7
—
—
4.9
5.3
7.9
7.1
10.5
6.3
9.4
8.5
12.6
100
80
1
/
. For
64
/
inch
1
2
MOUNTING
BOLTS (4)
Fig. 54 — Belt Drive Motor Mounting
Pre-Start and Start-Up
This completes the mechanical installation of the unit. Refer to the
unit's Service Manual for detailed Pre-Start and Start-Up instruc-
tions. Download the latest versions from HVAC Partners
(www.hvacpartners.com).
Typical Unit Piping
Each heat pump refrigeration system includes a compressor, ac-
cumulator, reversing valve, dual-function outdoor coil with va-
por header check valve, cooling liquid line with a filter drier and
a check valve, dual-function indoor coil with a vapor header
check valve, and heating liquid line with a check valve and a
strainer. See Fig. 55 and Tables 21-23 for typical unit piping
schematic. Dual-function outdoor and indoor coils are designed
to provide parallel coil circuits during evaporator-function oper-
ation and converging coil circuits during the condenser-function
operation.
6.1
7.4
8.4
7.2
46
BLOWER PULLEY
V-BELT
MOTOR
PULLEY
MOTOR
MOTOR MOUNTING
PLATE
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