Leaving Fluid Temperature Setpoints; Low Ambient Temperature Start - Trane RTAA-70 Installation & Maintenance Manual

98
Controls Interface
Table 17

Leaving Fluid Temperature Setpoints

The leaving chilled water temperature is not the same as the ice termination setpoint. The
ice termination setpoint is based on entering chilled water temperature. Therefore, the ice
termination setpoint, minus temperature drop across the evaporator while in the ice
making mode, equals the leaving chilled water temperature.
Leaving Leaving
Chilled Water Water Temp
Temp - F Cutout - F
40 35
39 34
38 33
37 32
36 31
35 30
34 29
33 28
32 27
31 26
30 25
29 24
28 23
27 22
26 21
25 20
24 19
23 18
22 17
21 16
20 15
19 14
18 13
17 12
16 11
15 10
14 9
13 8
12 7
11 6
10 5
9 4
8 3
7 2
6 1
5 0
4 -1
3 -2
2 -3
1 -4
0 -5
***Recommended% Ethylene Glycol will give freeze protection consistent with other chiller
safety controls (solution freeze point is nominally 10'F above refrig temp cutout).

Low Ambient Temperature Start

The Low Refrigerant Temperature Cutout (LRTC) and Low Pressure Cutout
(LPC) on a circuit is ignored, briefly, each time the circuit is started. The
"ignore time" is a function of the Saturated Condenser Refrigerant Temper-
ature at the time the compressor starts, as shown in Figure 36.
Low
Refrig Temp Recommended***
Cutout - F % Ethylene Glycol
22 0
20 3
18 6
17 8
15 10
14 12
12 14
11 15
9 17
7 19
6 20
4 21
2 23
0 25
-1 26
-3 28
-5 29
-6 30
-8 31
-10 33
-11 34
-13 35
-15 36
-17 37
-18 38
-19 39
-21 40
-23 41
-24 42
-26 43
-27 43
-29 44
-31 45
-32 46
-34 47
-35 47
-37 48
-38 49
-39 50
-39 50
-39 50
Solution
Freeze Point - F
32
25
21
16
10
4
-3
-11
-21
-32
RTAA-SVX01A-EN