Phasing; Supply Air Blowers; Checking Supply Air Cfm; Static Resistances - York SUNLINE DCG Series Installation Manual

TABLE 26: STATIC RESISTANCES
DESCRIPTION
1 3
ECONOMIZER
ELECTRIC
7-15KW
1
HEATERS
20-30KW
BOTTOM DUCT CONNECTIONS
2
COOLING ONLY
1. Deduct these resistance values from the available external static pressure shown in SUPPLY AIR BLOWER PERFORMANCE Tables.
2. Add these resistance values to the available static resistance values on SUPPLY AIR BLOWER PERFORMANCE Tables.
3. The pressure through the economizer is greater for 100% outdoor air than for 100% return air. If the resistance of the return air
duct system is less than 0.25 IWG, the unit will deliver less CFM during full economizer operation.

PHASING

Check for proper compressor rotation. If the blower or
compressors rotate in the wrong direction at start-up,
the electrical connection to the unit is misphased.
Change the incoming line connection phasing to obtain
proper rotation. (Scroll compressors operate in only
one direction. If the scroll is drawing low amperage,
has similar suction and discharge pressures, or pro-
ducing a high noise level, the scroll is misphased).
Scroll compressors require proper rotation to
operate correctly. Do not change the internal
wiring to make the blower, condenser fans, or
compressor rotate correctly. Change the
incoming power to the main terminal block to
obtain proper rotation.

SUPPLY AIR BLOWERS

These blowers have either 3-speed direct drive motors,
or single speed motors equipped with a belt drive. Belt
drive units have a variable pitch pulley that allows the
blower speed to be adjusted.

CHECKING SUPPLY AIR CFM

The RPM of the supply air blower will depend on the
required CFM, the unit accessories or options and the
static resistances of both the supply and the return air
duct systems. With this information, the motor speed
tap (direct drive) or the motor pulley number of turns
open (belt drive) can be determined from the Blower
Performance Data Tables.
38
1000 1200 1400
0.07 0.08 0.09
0.04 0.05 0.06
0.06 0.07 0.08
1
0.06 0.07 0.08
0.08 0.10 0.12
RESISTANCE, IWG
CFM
1600 1800 2000 2200
0.11 0.13 0.15 0.17
0.07 0.08 0.10 0.12
0.09 0.11 0.13 0.15
0.09 0.10 0.11 0.12
0.14 0.16 0.18 0.20
PROCEDURE FOR ADJUSTING BELT TENSION:
1. Loosen nuts (A) (top and bottom).
2. Adjust the tension by turning bolt (B).
3. Never loosen nuts (C) from each other.
4. Use a belt tension checker to apply a perpendicular force to be one belt at the
midpoint of the span as shown. The deflection force should be applied
until a specific deflection distance of 4mm (5/32") is obtained. To determine
the deflection distance from normal position, use a straight edge from
sheave to sheave as a reference line. The recommended deflection force
is as follows:
(A)
Tension new belts at the max. deflection force recommended for the belt
section. Check the belt tension at least two times during the first 24 hours of
operation. Any re-tensioning should fall between the min. and max.
deflection force values.
5. After adjusting, re-tighten nuts (A).
FIGURE 16 - BELT ADJUSTMENT
Note the following:
1. The supply air CFM must be within the limitations
shown in the Unit Application Data Table 1.
2. Pulleys can be adjusted in half turn increments.
3. The tension on the belt should be adjusted as
shown in the Belt Adjustment Figure 16.
290699-YIM-B-0607
2400 2600 2800
0.20 0.23 0.26
0.14 0.16 0.19
0.17 0.20 0.23
0.14 0.16 0.19
0.23 0.26 0.29
DEFL FORCE
(B)
*Never Loosen
(C)*
Unitary Products Group
3000
0.30
0.22
0.26
0.22
0.32