Catalogue
UH-PRC001-EN 25
Performance Data
To obtain the BTU capacity for conditions other than those in the basic capacity tables, multiply the basic rating (200° entering water, 60° entering air) by the proper constant
from Table 17.
Table 16. HOT WATER CALCULATIONS AND CORRECTION FACTORS
EXAMPLE:
UNIT:__________________P-42
Entering Water Temp. _____160°F
Entering Air Temp. ________ 40°F
Water Temperature Drop ____ 10°F
I. CAPACITY @ 20° TD:
A. For 200° EWT, 60° EAT
Read output directly from Tab l e 1 4 & Ta b le 1 5,
22,700 BTU/HR (Ref., Std. P-42, p. 22).
B. For EWT and/or EAT above or below
Standard
Multiply output from Ta b le 1 4 & Tab le 1 5 by factor from
Tab le 1 7 .
22,700 x .878 = 19,931 BTU/HR.
II. CAPACITY AT OTHER TD's
A. For TD's from 5 to 60°F
Multiply output obtained in IA. or IB.
(above) by appropriate factor from Tabl e 1 8
IA - 22,700 x 1.15 = 26,105 BTU/HR.
-OR-
IB - 19,931 x 1.15 = 22,921 BTU/HR.
III. GPM AT OTHER TD's
A. For TD's from 5 to 60°F
Multiply GPM of unit for 20° TD, from Ta ble 1 4 by
appropriate factor from Tabl e 1 8
2.34 x 2.30 = 5.38 GPM (Applies only
to units with. Std. 200° EWT, 60° EAT.)
For all others calculate using formula -
GPM = BTU/500 x TD
IV. PRESSURE LOSS AT OTHER TD's
A.ForTD's from 5 to 60°F
Multiply P.D. of unit for 20° TD, from Ta b l e 1 4 & Ta b le 1 5
by appropriate factor from Tabl e 1 8
.06 x 5.00 = .30 Ft. H
2
O
Table 17. HOT WATER CONVERSION FACTORS BASED ON 200° ENTERING WATER 60° ENTERING AIR 20° TEMPERATURE DROP
ENTERING AIR
TEMPERATURE
ENTERING WATER TEMPERATURE -20° WATER TEMPERATURE DROP
100° 120° 140° 160° 180° 200° 220° 240° 260° 280° 300°
30° 0.518 0.666 0.814 0.963 1.120 1.268 1.408 1.555 1.702 1.850 1.997
40° 0.439 0.585 0.731 0.878 1.025 1.172 1.317 1.464 1.609 1.755 1.908
50° 0.361 0.506 0.651 0.796 0.941 1.085 1.231 1.375 1.518 1.663 1.824
60° 0.286 0.429 0.571 0.715 0.857 1.000 1.143 1.286 1.429 1.571 1.717
70° 0.212 0.353 0.494 0.636 0.777 0.918 1.060 1.201 1.342 1.483 1.630
80° 0.140 0.279 0.419 0.558 0.698 0.837 0.977 1.117 1.257 1.397 1.545
90° 0.069 0.207 0.345 0.483 0.621 0.759 0.897 1.035 1.173 1.311 1.462
100° 0 0.137 0.273 0.409 0.546 0.682 0.818 0.955 1.094 1.230 1.371
Table 18. 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
USE FACTORS FROM THIS TABLE TO OBTAIN
APPROXIMATE RESULTS
TEMPERATURE DROP °F
510152025 30 4050 60
To obtain BTU for other Water Temperature Drops,
multiply basic BTU rating by applicable Factor.
1.25 1.15 1.08 1.00 .94 .90 .83 .76 .72
To obtain GPM for other Water Temperature Drops,
multiply basic GPM rating by applicable Factor.*
5.00 2.30 1.44 1.00 .74 .59 .40 .30 .24
To obtain Pressure Loss Feet of Water for other
temperature Drops, multiply Basic loss at 20° drop by
Factor.
10.00 5.00 2.00 1.00 .60 .40 .20 .13 .07
Table 19. *MINIMUM WATER FLOW - GPM
MODEL No. 42 64 80 102 146 166 202 252 336 384 500 600 700
MIN. GPM .55 .55 .55 .55 .82 .82 1.10 1.10 1.10 1.10 1.0 1.4 1.6
Table 20. *HEATING CAPACITY FACTORS FOR VARIOUS RATES OF WATER FLOW
% of Rated Water Flow 25% 50% 75% 100% 125% 150% 175%
Btu/Hr Heating Capacity .80 .89 .96 1.00 1.04 1.07 1.10