Bryant Base Series Application Manual And Service Manual page 27

Residential Air Conditioners and Heat Pumps Using R-22 and Puron® Refrigerant: Application Guideline and Service Manual
line-set connection ports. All heat pumps that are equipped with an
AccuRater piston heating metering device are shipped with an adapter
stub tube. This tube must be installed on the liquid service valve. After
connecting the stub tube to the liquid service valve of a heat pump, the
valves are ready for brazing. The interconnecting tubing (line set) can be
brazed to the service valves using industry accepted methods and
materials. Consult local codes.
Before brazing the line set to the valves, the belled ends of the sweat
connections on the service valves must be cleaned so that no brass
plating remains on either the inside or outside of the bell joint. To
prevent damage to the valve and/or cap "O" ring, use a wet cloth or other
acceptable heat-sinking material on the valve before brazing. To prevent
damage to the unit, use a metal barrier between brazing area and unit.
After the brazing operation and the refrigerant tubing and evaporator coil
have been evacuated, the valve stem can be turned counterclockwise
until back-seats, which releases refrigerant into tubing and evaporator
coil. The system can now be operated.
Back-seating service valves
counterclockwise until seated) before the service-port caps can be
removed and hoses of gauge manifold connected. In this position,
refrigerant has access from and through outdoor and indoor unit.
The service valve-stem cap is tightened to 20 ± 2 ft/lb torque and the
service-port caps to 9 ± 2 ft/lb torque. The seating surface of the valve
stem has a knife-set edge against which the caps are tightened to attain a
metal-to-metal seal. If accessory pressure switches are used, the service
valve must be cracked. Then, the knife-set stem cap becomes the
primary seal.
The service valve cannot be field repaired; therefore, only a complete
valve or valve stem and service-port caps are available for replacement.
If the service valve is to be replaced, a metal barrier must be inserted
between the valve and the unit to prevent damaging the unit exterior
from the heat of the brazing operations.
CAUTION
!
PERSONAL INJURY HAZARD
Failure to follow this caution may result in personal injury.
Wear safety glasses, protective clothing, and gloves when handling
refrigerant.
Pumpdown Procedure
Service valves provide a convenient shutoff valve useful for certain
refrigeration-system repairs. System may be pumped down to make
repairs on low side without losing complete refrigerant charge.
1. Attach pressure gauge to suction service-valve gauge port.
2. Front seat liquid-line valve.
3. Start unit in cooling mode. Run until suction pressure reaches 5
psig (35kPa). Do not allow compressor to pump to a vacuum.
4. Shut unit off. Front seat suction valve.
NOTE: All outdoor unit coils will hold only factory-supplied amount of
refrigerant. Excess refrigerant, such as in long-line applications, may
cause unit to relieve pressure through internal pressure-relief valve
(indicated by sudden rise of suction pressure) before suction pressure
reaches 5 psig (35kPa). If this occurs, shut unit off immediately, front
seat suction valve, and recover remaining pressure.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
must be back-seated (turned
Heating Piston (AccuRater®) - Heat Pumps Only
AccuRater pistons are used to meter refrigerant for heat pump heating
mode only. All indoor coils are supplied with a bi-flow TXV for
metering in the cooling mode. AccuRater piston has a refrigerant
metering hole through it. The piston seats against the piston body in
heating mode and meters the refrigerant in heating mode and allows
refrigerant to flow around it in cooling mode.
There are 2 types of liquid line connections used. Flare connections are
used in R-22 systems.
1. Shut off power to unit.
2. Pump unit down using pumpdown procedure described in this
service manual.
3. Loosen nut and remove liquid line flare connection from
AccuRaterr.
4. Pull retainer out of body, being careful not to scratch flare sealing
surface. If retainer does not pull out easily, carefully use locking
pliers to remove it.
5. Slide piston and piston ring out by inserting a small soft wire with
small kinks through metering hole. Do not damage metering hole,
sealing surface around piston cones, or fluted portion of piston.
6. Clean piston refrigerant metering hole.
7. Install a new retainer O-ring, retainer assembly, or Teflon washer
before reassembling AccuRater.
Fig. 20 – Front Seating Service Valve with Chatleff Connection Used
in Legacy, and 4-Sided Preferred and Evolution Puron Heat Pumps.
Fig. 21 – AccuRaterr Components
(used in R-22 Heat Pumps)
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