Hot water calculations and correction factor – Sterling VS User Manual
Page 12
12
EXAMPLE: –
UNIT SIZE _______________________ 40
Entering
Water
Temp.
____________ 160°F
Entering
Air
Temp.
_______________ 40°F
Water
Temperature
Drop
__________ 10°F
I.
CAPACITY @ 20°F TD:
A. For 200°F EWT, 60°F EAT
Read output directly from Tables 7 & 8,
22,700 BTU/HR (Ref., Std. 40, p. 8).
B. For EWT and/or EAT above
Multiply output from Tables 7 & 8
or below Standard
by factor from Table 9 (below).
22,700 x .878 = 19,931 BTU/HR.
II. CAPACITY AT OTHER TD’s
Multiply output obtained in IA or IB
IA - 22,700 x 1.15 = 26,105 BTU/HR.
A. For TD’s from 5 to 60°F
(above) by appropriate factor from Table 10
– OR –
(below)
IB - 19,931 x 1.15 = 22,921 BTU/HR.
III. GPM AT OTHER TD’s
Multiply GPM of unit for 20°F TD, from Tables 7 & 8
2.34 x 2.30 = 5.38 GPM (Applies only to units with
A. For TD’s from 5 to 60°F
by appropriate factor from Table 10 (below).
Std. 200°F EWT, 60°F EAT) For all others calculate
BTU
using formula – GPM =
500 x TD
IV. PRESSURE LOSS AT OTHER TD’s
Multiply P.D. of unit for 20°F TD, from Tables 7 & 8
A.For TD’s from 5 to 60°F
by appropriate factor from Table 10 (below).
.06 x 5.00 = .30 Ft. H
2
O
367
1.10
(.069)
10 (6)
1.15
2.30
5.00
60 (33)
.72
.24
.07
280°
(138°)
1.850
1.755
1.663
1.571
1.483
1.397
1.311
1.230
260°
(127°)
1.702
1.609
1.518
1.429
1.342
1.257
1.173
1.094
240°
(116°)
1.555
1.464
1.375
1.286
1.201
1.117
1.035
0.955
220°
(104°)
1.408
1.317
1.231
1.143
1.060
0.977
0.897
0.818
200°
(93°)
1.268
1.172
1.085
1.000
0.918
0.837
0.759
0.682
180°
(82°)
1.120
1.025
0.941
0.857
0.777
0.698
0.621
0.546
160°
(71°)
0.963
0.878
0.796
0.715
0.636
0.558
0.483
0.409
140°
(60°)
0.814
0.731
0.651
0.571
0.494
0.419
0.345
0.273
120°
(49°)
0.666
0.585
0.506
0.429
0.353
0.279
0.207
0.137
100°
(38°)
0.518
0.439
0.361
0.286
0.212
0.140
0.069
0
300°
(149°)
1.997
1.908
1.824
1.717
1.630
1.545
1.462
1.371
30°
(-1)
40°
(4)
50°
(10)
60°
(16)
70°
(21)
80°
(27)
90°
(32)
100°
(38)
TABLE 9 — HOT WATER CONVERSION FACTORS BASED ON 200°F ENTERING WATER
60°F ENTERING AIR 20°F TEMPERATURE DROP
To obtain the BTU capacity for conditions other than those in the basic capacity tables, multiply the basic rating
(200°F entering water, 60°F entering air,) by the proper constant from the above tables.
TABLE 10 — HOT WATER BTU, GPM AND PRESSURE LOSS FACTORS BASED ON STANDARD
CONDITIONS OF 200°F ENTERING WATER 60°F ENTERING AIR & 20°F WATER DROP
UNIT SIZE
MIN.
GPM (L/s)
*TABLE 12 — HEATING CAPACITY FACTORS FOR VARIOUS RATES OF WATER FLOW
*TABLE 11 — MINIMUM WATER FLOW — GPM
ENTERING AIR
TEMPERATURE °F (°C)
ENTERING WATER TEMPERATURE — 20°F WATER TEMPERATURE DROP
TEMPERATURE DROP °F (°C)
USE FACTORS FROM THIS TABLE TO OBTAIN
APPROXIMATE RESULTS
To obtain BTU for other Water Temperature Drops,
multiply basic BTU rating by applicable Factor.
To obtain GPM for other Water Temperature Drops,
multiply basic GPM rating by applicable Factor.*
To obtain Pressure Loss Feet of Water for other
temperature Drops, multiply Basic loss at 20°F drop by
Factor.
175%
1.10
25%
.80
75%
.96
125%
1.04
150%
1.07
50%
.89
% of Rated Water Flow
Btu/Hr Heating Capacity
100%
1.00
40
.55
(.035)
62
.55
(.035)
77
.55
(.035)
104
.55
(.035)
144
.82
(.052)
164
.82
(.052)
200
1.10
(.069)
237
1.10
(.069)
317
1.10
(.069)
HOT WATER CALCULATIONS AND CORRECTION FACTOR
50 (28)
.76
.30
.13
40 (22)
.83
.40
.20
30 (17)
.90
.59
.40
20 (11)
1.00
1.00
1.00
25 (14)
.94
.74
.60
15 (8)
1.08
1.44
2.00
5 (3)
1.25
5.00
10.00