System Configuration; Unit Components - Lennox Merit Series Installation Instructions Manual

Charging
The 16HPX unit is factory-charged with enough HFC-
410A refrigerant to accommodate a 15-foot length of re-
frigerant piping. Charge should be checked and adjusted
using the tables provided on the charging procedure stick-
er on the unit access panel. Detailed information is given
in the 16HPX Installation and Service Procedures manual,
which is available on LennoxPros.com.

System Configuration

This section addresses:
• Unit components (sensors, temperature switch, pres-
sure switches and demand defrost control)
• Second-stage operation
TEST PINS (P1)
DEFROST TERMINATION
PIN SETTINGS (P1)
SENSOR CONNECTION
(COIL AND AMBIENT
SENSORS)
(P4)
DELAY PINS
(P5)
REVERSING VALVE
(O OUT)
PRESSURE
SWITCH CIRCUIT
CONNECTIONS
Note - Component locations vary by board manufacturer.
FIGURE 15
Page 13

UNIT COMPONENTS

Demand Defrost Control (A108)
The demand defrost control measures differential tem-
peratures to detect when the system is performing poorly
because of ice build-up on the outdoor coil. The control
self-calibrates when the defrost system starts and after
each system defrost cycle. The demand defrost control
components are shown in figure 15.
• Demand defrost control connections, jumpers and LED
locations are shown in figure 15.
• Demand defrost control connections, jumpers and LED
descriptions are listed on table 2.
• Demand defrost control status, fault and lockout LEDs
are listed in table 3.
LOW AMBIENT
THERMOSTAT PINS
(P3)
DIAGNOSTIC LEDS
(DS1 AND DS2)
24V TERMINAL STRIP
CONNECTIONS
(P2)
Demand Defrost
Control (A108)