Carrier SINGLE PACKAGE ROOFTOP UNITS ELECTRIC COOLING/GAS HEATING 48HJ015-025 - Manual (Page 10)

Use the following formula to determine the percent volt-
age imbalance.
% Voltage Imbalance:
= 100 x
max voltage deviation from average voltage
average voltage
EXAMPLE: Supply voltage is 460-3-60.
AB =452 v
BC =464 v
AC =455 v
Average Voltage =
452 +464 +455
3
=
1371
3
= 457
Determine maximum deviation from average voltage:
(AB) 457 −452 =5 v
(BC) 464 −457 =7 v
(AC) 457 −455 =2 v
Maximum deviation is 7 v.
Determine percent voltage imbalance:
% Voltage Imbalance =100 x
7
457
=1.53%
This amount of phase imbalance is satisfactory as it is be-
low the maximum allowable 2%.
IMPORTANT: If the supply voltage phase imbalance
is more than 2%, contact your local electric utility com-
pany immediately.
Unit failure as a result of operation on improper line
voltage or excessive phase imbalance constitutes abuse and
may cause damage to electrical components.
FIELD CONTROL WIRING — Install a Carrier-approved
accessory thermostat assembly according to installation
instructions included with accessory. Locate thermostat as-
sembly on a solid interior wall in the conditioned space to
sense average temperature.
Route thermostat cable or equivalent single leads of col-
ored wire from subbase terminals through conduit in unit to
low-voltage connections as shown on unit label wiring dia-
gram and in Fig. 15.
NOTE: For wire runs up to 50 ft, use no. 18 AWG (Ameri-
can Wire Gage) insulated wire (35 C minimum). For 50 to
75 ft, use no. 16 AWG insulated wire (35 C minimum). For
over 75 ft, use no. 14 AWG insulated wire (35 C minimum).
All wire larger than no. 18 AWG cannot be directly con-
nected at the thermostat and will require a junction box and
splice at the thermostat.
Set heat anticipator settings as follows:
UNIT VOLTAGE UNIT W1 W2
48HJD015 All 1.20 —
48HJD025, HJE015,
HJE017
All 1.20 0.60
Settings may be changed slightly to provide a greater de-
gree of comfort for a particular installation.
Refer to Accessory Remote Control Panel instructions if
required.
Step 9 — Make Outdoor-Air Inlet Adjustments
MANUAL OUTDOOR-AIR DAMPER — All units (except
those equipped with a factory-installed economizer) have a
manual outdoor-air damper to provide ventilation air.
Damper can be preset to admit up to 25% outdoor air into
return-air compartment. To adjust, loosen securing screws
and move damper to desired setting, then retighten screws to
secure damper (Fig. 16).
OPTIONAL FACTORY-INSTALLED ECONOMIZER
Economizer Motor Control Module (See Fig. 17-19) — Set
economizer motor to the D setting (Fig. 18).
Damper Vent Position Setting
1. Set fan switch at ON position (continuous fan operation)
and close night switch if used.
2. Set system selector switch at OFF position.
3. Turn damper adjustment knob located on control module
clockwise slowly until dampers assume desired vent po-
sition. Do not manually operate economizer motor. Dam-
age to motor will result.
NOTE: Refer to accessory installation instructions included
with the field-installed economizer for installation informa-
tion. Also see Accessory Field-Installed Economizer Adjust-
ment section on page 12.
Step 10 — Install Outdoor-Air Hood — The outdoor-
air hood is common to 25% air ventilation and economizer.
If economizer is used, all electrical connections have been
made and adjusted at the factory. Assemble and install hood
in the field.
NOTE: The hood top cover, upper and lower filter retain-
ers, hood drain pan, baffle (017 and 025 only), and filter sup-
port bracket are secured opposite the condenser end of the
unit. The screens, hood side panels, remaining section of fil-
ter support bracket, seal strip, and hardware are in a package
located inside the return-air filter access panel (Fig. 20).
1. Attach seal strip to upper filter retainer. See Fig. 21.
2. Assemble hood top cover, side panels, upper filter re-
tainer, and drain pan (see Fig. 22).
3. Secure lower filter retainer and long portion of support
bracket to unit. See Fig. 22. Leave screws loose on 017
and 025 units.
4. 48HJ017,025 Units Only: Slide baffle behind lower filter
retainer and tighten screws.
Fig. 15 — Field Control Thermostat Wiring
Fig. 16 — 25% Outdoor-Air Section Details
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