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G− Crankcase heater Thermostat (S40)
Thermostat S40 controls the crankcase heater in all units.
S40 is located on the liquid line. When liquid line tempera-
ture drops below 50° F the thermostat S40 closes energizing
HR1. The thermostat will open, de−energizing HR1 once liq-
uid line temperature reaches 70° F .
H−Filter Drier
A filter drier designed for all HPXA16 model units is factory
installed in the liquid line. The filter drier is designed to re-
move moisture and foreign matter, which can lead to com-
pressor failure.
Moisture and / or Acid Check
Because POE oils absorb moisture, the dryness of the
system must be verified any time the refrigerant sys-
tem is exposed to open air.
A
c
ompressor oil sample
must be taken to determine if excessive moisture has been
introduced to the oil. Table 3 lists kits available from Lennox
to check POE oils.
If oil sample taken from a system that has been exposed to
open air does not test in the dry color range, the filter drier
MUST be replaced.
IMPORTANT
Replacement filter drier MUST be approved for
R−410A refrigerant and POE application.
Foreign Matter Check
It is recommended that a liquid line filter drier be replaced
when the pressure drop across the filter drier is greater
than 4 psig.
I−Accumulator (HPXA16−060 only)
ALL 5 ton HPXA16 units are equipped with an accumulator.
The purpose of the accumulator is to trap and evaporate all
liquid refrigerant returning to the compressor.
J−Charge Compensator
HPXA16−048 series units are equipped with a charge com-
pensator located in the vapor line between the reversing
valve and outdoor coil manifold. The compensator is used
to collect and store excess refrigerant in the heating mode.
Figure 11 shows operation of the charge compensator.
In heating mode, the vapor line passing through the charge
compensator tank is cooler than the liquid line. Excess re-
frigerant (condensed liquid) from the indoor coil is trapped
by the compensator. The vapor line is cooler than the liquid
line so liquid migrates from the liquid line to the compensa-
tor tank where it is stored. In cooling mode, the vapor line
passing through the charge compensator tank is hotter
than the liquid line. Stored liquid is boiled and forced back
into the liquid line for circulation.
FIGURE 11
CHARGE COMPENSATOR OPERATION
During cooling mode, the va-
por line is hotter than the liq-
uid line. Stored liquid is
heated (boiled) and forced
back into circulation.
During heating mode, the va-
por line is cooler than the liq-
uid line. Excess refrigerant is
forced into the charge com-
pensator where it condenses
and collects.
Vapor Line
(To Outdoor Coil)
Vapor Line
(From Compressor Discharge Port)
Vapor Line
(From Outdoor Coil)
Vapor Line
(To Compressor Suction Port)
Stored Liquid
To Liquid Line
To be Circulated
Through Indoor Coil
Excess Refrigerant
To be Condensed and Stored
as Liquid
Compensator Tank
Compensator Tank
COOLING MODE
HEATING MODE
K−Crankcase Heater (HR1)
Compressors in all units are equipped with a 70 watt belly-
band type crankcase heater. HR1 prevents liquid from ac-
cumulating in the compressor. HR1 is controlled by the
crankcaseheater thermostat.
L−Defrost System
The demand defrost controller measures differential tem-
peratures to detect when the system is performing poorly
because of ice build−up on the outdoor coil. The controller
self−calibrates" when the defrost system starts and after
each system defrost cycle. The defrost control board com-
ponents are shown in figure 12.
TABLE 3
KIT
CONTENTS
TUBE SHELF LIFE
10N46 − Refrigerant Analysis
Checkmate−RT700
10N45 − Acid Test Tubes
Checkmate−RT750A (three pack)
2 − 3 years @ room temperature. 3+
years refrigerated
10N44 − Moisture Test Tubes
Checkmate − RT751 Tubes (three
pack)
6 − 12 months @ room temperature. 2
years refrigerated
74N40 − Easy Oil Test Tubes
Checkmate − RT752C Tubes (three
pack)
2 − 3 years @ room temperature. 3+
years refrigerated
74N39 − Acid Test Kit
Sporlan One Shot − TA−1
