70
YORK INTERNATIONAL
PIPING
Factory mounted Hot Gas Piping is shown in Fig. 27. A
field piping connection must be made from the Hot Gas
Solenoid to the refrigerant system between the Expan-
sion Valve and the DX Coil or the Evaporator (Fig. 27).
In addition, connection of the equalizing line is re-
quired. ASHRAE practices should be followed when
installing this piping.
LOADMINDER OPERATION
The Hot Gas Solenoid is energized by the micropro-
cessor on compressor start as the first step of the load-
ing sequence. The Solenoid will also be energized when
all Loading Solenoids are energized (energize to un-
load) and the micro sees suction pressure drop below
the Suction Pressure Setpoint. This is the micro’s effort
to energize hot gas to false load the system and keep
the compressor on line in response to a drop in load.
If suction pressure rises above the “Control Zone” while
the Hot Gas Solenoid is energized (load increases),
the compressor will go to the next step of loading which
is running the compressor unload with no hot gas. This
is accomplished by de-energizing the Hot Gas Solenoid.
If suction pressure drops below the “Control Zone” when
running the compressor totally unloaded, the Hot Gas
Solenoid will again be energized and will remain ener-
gized until the Zone Thermostat/Cycling Device shuts
the compressor off or suction pressure rises due to
increasing load.
Even though suction pressure may require energizing
or de-energizing, the Hot Gas Solenoid will only take
place after the initial timers for loading and unloading
are satisfied.
The amount of hot gas which flows when the Hot Gas
Solenoid is energized is a function of the regulator ad-
justment and system suction pressure.
Procedure For Setting The Loadminder
(Ref. Fig. 27)
1.
If desired, set the control panel data to show suc-
tion pressure.
2.
Adjust the pilot power assembly adjustment screw
â
to approximately the middle of its adjustment
range.
3.
The chiller must be running and stabilized on the
minimum stage of capacity. In establishing this
condition, it may be necessary to deactivate the
regulator by de-energizing the solenoid
ã
.
4.
Adjust the adjustment screw
ã
in the clockwise
direction to open the valve at a higher pressure
(sooner) or in the counter clockwise direction to
open the valve at a lower pressure (slower re-
sponse). The valve is feeding when the valve out-
let feels warm to the touch.
The adjustment is correct when system suction
pressure rises to a point nearly equal to normal
running pressure at midpoint in the “Control Zone”.
5.
Further minor adjustment may be necessary to
be certain that the valve opens fully before the
point at which the Zone Thermostat cycles off the
compressor.
FIG. 27 – PIPING DIAGRAM
LD00580
LD00581
LD00582(R)
SYSTEM #2
Connect to a point between the
Expansion Valve and Evaporator
or DX Coil (Air Handling Unit)
SYSTEM #1
Connect to a point between the
Expansion Valve and Evaporator
or DX Coil (Air Handling Unit)
Содержание YCUZ330A3
Страница 79: ...FORM 195 26 NM3 YORK INTERNATIONAL 79 LD00643...
