York YCH120 - Page 56

YORK INTERNATIONAL
56
(YCHA120, 150, 175 & 200)
** 10°F ÷ 8 stages = 1 .25°F between stages of loading.
*** If optional 6 stage loading/unloading is included, Stage 4 loading and unloading is not included on either compressor. Therefore, in the
example above, no system response will take place on loading at 50°F and 55°F and no system response will take place on unloading
at 53.75°F and 48.75°F.
LOADING/UNLOADING
(RETURN WATER TEMPERATURE (RWT)
CONTROL – STANDARD)
Loading/Unloading of cylinders is accomplished in re-
sponse to return chilled water temperature as sensed
by the Micro Logic Board. Cooling Ranges from 6 to
14°F can be selected to control loading/unloading. A
typical example is illustrated below (4 stages).
RWT Setpoint = 55° F
Cooling Range = 10°
System Switches = Both ON
SYS l = LEAD
J8 on Micro Logic = OUT
or
Sw. 5 on Micro = OFF
J10 on Micro Logic = OUT
or
Sw. 3 on Micro = OFF
If optional 6 or 8 stages of unloading is included, typical
loading and unloading is illustrated below.
RWT Setpoint = 55° F
Cooling Range = 10°
System Switches = Both ON
SYS 1 = LEAD
J8 on Micro Logic = IN
or
Sw. 5 on Micro = ON
J10 on Micro Logic = OUT
or
Sw. 3 on Micro = OFF
Typical 4 stages of unloading
}
}
RWT Control
Optional 6 or 8 stages of unloading
}
}
RWT Control
Return Water
Temp. °F
55 -------------------- --------- Lag Compressor Loads Stage 2 ------- -------------------------------------
Cooling 52.5------------------ --------- Lag Compressor Starts (Unloaded) -- – Lag Compressor Unloader Stage 2
Range 50.0------------------ --------- Lead Compressor Loads Stage 2 ----- – Lag Compressor Off
*10°F 47.5------------------ --------- Lead Compressor Starts (Unloaded) - – Lead Compressor Unloads Stage 2
45 -------------------- --------- Both Compressors OFF ----------------- – Lead Compressor OFF
*10°F ÷ 4 stages = 2.5°F between stages of loading.
Temperature
Fall
Temperature
Rise
➤
➤
Return WaterTemp. °F
55 -------------------- --------- Lag Compressor Loads Stage 4** ---- -------------------------------------
Cooling 53.75 ---------------- --------- Lag Compressor Loads Stage 3------- – Lag. Compr. Unloads Stage 4 ***
Range 52.5------------------ --------- Lag Compressor Loads Stage 2 ------- – Lag Compr. Unloads Stage 3
**10°F 51.25 ---------------- --------- Lag Compr. Starts (Unloaded) Stage 1 – Lag Compr. Unloads Stage 2
50 -------------------- --------- Lead Compressor Loads Stage 4*** - – Lag Compr. OFF
48.75 ---------------- --------- Lead Compressor Loads Stage 3 ----- – Lead Compr. Unloads Stage 4***
47.5------------------ --------- Lead Compressor Loads Stage 2 ----- – Lead Compr. Unloads Stage3
46.25 ---------------- --------- Lead Compr. Starts (Unloaded) Stg 1 – Lead Compr. Unloaded Stage 2
45.0------------------ --------- Both Compressors OFF ----------------- – Lead Compr. OFF (Stage 1)
Temperature
Fall
Temperature
Rise
➤
➤