Charging; S-105B Thermostatic Expansion Valve - Daikin DAR09 Service Instructions Manual

SERVICING
LOW SIDE
GAUGE
AND VALVE AND VALVE
800 PSI
RATED
HOSES
TO
UNIT SERVICE
VALVE PORTS
VACUUM PUMP
EVACUATION
3. If the vacuum pump is working properly, close the valve to
the vacuum thermocouple gauge and open the high and low
side valves to the high vacuum manifold set. With the valve
on the charging cylinder closed, open the manifold valve to
the cylinder.
4. Evacuate the system to at least 29 inches gauge before open-
ing valve to thermocouple vacuum gauge.
5. Continue to evacuate to a maximum of 250 microns. Close
valve to vacuum pump and watch rate of rise. If vacuum
does not rise above 1500 microns in three to five minutes,
system can be considered properly evacuated.
6. If thermocouple vacuum gauge continues to rise and levels
off at about 5000 microns, moisture and non-condensables
are still present. If gauge continues to rise a leak is present.
Repair and re-evacuate.
7. Close valve to thermocouple vacuum gauge and vacuum
pump. Shut off pump and prepare to charge.
HIGH SIDE
GAUGE

CHARGING

CYLINDER
AND SCALE
VACUUM PUMP
ADAPTER
S-103 CHARGING
WARNING
REFRIGERANT UNDER PRESSURE!
* Do not overcharge system with refrigerant.
* Do not operate unit in a vacuum or at negative
pressure.
Failure to follow proper procedures may cause
property damage, personal injury or death.

S-105B THERMOSTATIC EXPANSION VALVE

The expansion valve is designed to control the rate of liquid re-
frigerant flow into an evaporator coil in exact proportion to the
rate of evaporation of the refrigerant in the coil. The amount of
refrigerant entering the coil is regulated since the valve responds
to temperature of the refrigerant gas leaving the coil (feeler
bulb contact) and the pressure of the refrigerant in the coil. This
regulation of the flow prevents the return of liquid refrigerant to
the compressor.
The illustration below shows typical heatpump TXV/check valve
operation in the heating and cooling modes.
COOLING
Some TXV valves contain an internal check valve thus eliminat-
ing the need for an external check valve and bypass loop. The
three forces which govern the operation of the valve are: (1)
the pressure created in the power assembly by the feeler bulb,
(2) evaporator pressure, and (3) the equivalent pressure of the
superheat spring in the valve.
0% bleed type expansion valves are used on indoor and outdoor
coils. The 0% bleed valve will not allow the system pressures
(High and Low side) to equalize during the shut down period.
The valve will shut off completely at approximately 100 PSIG.
30% bleed valves used on some other models will continue to
allow some equalization even though the valve has shut-off com-
pletely because of the bleed holes within the valve. This type of
valve should not be used as a replacement for a 0% bleed valve,
due to the resulting drop in performance.
The bulb must be securely fastened with two straps to a clean
straight section of the suction line. Application of the bulb to a
horizontal run of line is preferred. If a vertical installation cannot
be avoided, the bulb must be mounted so that the capillary
tubing comes out at the top.
THE VALVES PROVIDED BY DAIKIN ARE DESIGNED TO MEET
THE SPECIFICATION REQUIREMENTS FOR OPTIMUM PRODUCT
OPERATION. DO NOT USE SUBSTITUTES.
70
HEATING
TXV VALVES