Bulletin 30-015.003
Copyright © 2017 Unico Inc.
Page 15
Using a High Head Kit (Mild Weather Kit).
When
any heat pump is operated during mild weather
(temperatures above 50°F (10 C)), the compressor may
trip out on the high pressure limit. The Unico System
is particularly sensitive to this since it operates at a
higher pressure.
To overcome this problem, install a mild weather kit
(UPC-65X) to cycle the outdoor fan based on the
compressor discharge pressure. However, be sure this
control is compatible with the outdoor heat pump
section being used.
Table 5 R410A Saturation Pressure - Temperature
°F
psig
°C
kPa (gauge)
0
48.4
-18
330
2
51.1
-17
347
4
53.8
-16
363
6
56.6
-15
380
8
59.4
-14
398
10
62.4
-13
416
12
65.4
-12
434
14
68.6
-11
453
16
71.8
-10
473
18
75.1
-9
493
20
78.5
-8
513
22
82.1
-7
534
24
85.7
-6
556
26
89.4
-5
578
28
93.2
-4
601
30
97.2
-3
624
32
101.0
-2
648
34
105.0
-1
673
36
110.0
0
698
38
114.0
1
723
40
119.0
2
750
42
123.0
3
777
44
128.0
4
804
46
133.0
5
833
48
138.0
6
861
50
143.0
7
891
55
156.0
8
922
60
170.0
9
953
.
.
.
.
.
.
10
984
90
274.0
12
1050
95
295.0
14
1120
100
317.0
.
.
.
.
.
.
105
341.0
30
1780
110
365.0
32
1880
115
391.0
34
1980
120
418.0
36
2090
125
447.0
38
2200
130
477.0
40
2320
42
2440
44
2560
46
2690
48
2820
50
2960
52
3100
54
3250
