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Step 14 — Check Belt Tension
Measure the belt span length as shown in Fig. 54. Calculate the
required deflection by multiplying the belt span length by
For example, if the belt span length is 32 inches: 32 x
1
/
inch deflection.
2
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. 54). 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. 55) and slide the plate towards the
fan (to reduce tension) or away from the fan (to increase ten-
sion). 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
3.7
A, AX
3.8-4.8
4.5
5.0-7.0
5.4
3.4-4.2
B, BX
4.4-5.6
5.3
5.8-8.6
6.3
Table 1
BELT CONDITION
TENSION FORCE IN BELT (LBS)
New
Used
Table 2
Fig. 54 — V-Belt Force Label
NOTCHED BELTS
BELTS
NEW
USED
NEW
5.5
4.1
6.8
5.0
8.0
5.7
—
—
4.9
7.9
7.1
10.5
9.4
8.5
12.6
100
80
1
/
.
64
/
=
1
64
MOUNTING
BOLTS (4)
Fig. 55 — 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
instructions. Download the latest versions from HVAC Part-
ners (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. Unit sizes A04-06 have a single compressor-circuit. See
Fig. 56 and Tables 17-19 for typical unit piping schematic. Dual-
function outdoor and indoor coils are designed to provide paral-
lel coil circuits during evaporator-function operation and con-
verging coil circuits during the condenser-function operation.
6.1
7.4
8.4
7.2
45
BLOWER PULLEY
V-BELT
MOTOR
PULLEY
MOTOR
MOTOR MOUNTING
PLATE
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