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Table SP-10 - Maximum Mounting Heights in Feet for Model P Unit Heaters
with and without Louver Cone Diffuser
Unit
Steam Pressure (PSI)
Size
2
5
10
50
42-P
10.5
10.0
10.0
9.0
12.5 12.0 12.0 11.0 10.0
42-P LS*
8.0
8.0
8.0
8.0
9.0
8.5
8.5
8.0
42-P-L**
12.5
12.0
12.0
10.5
14.5 14.0 13.5 12.0 11.5
42-P-L LS
9.0
8.5
8.5
8.0
10.5 10.0 10.0
9.0
64-P
12.0
11.5
11.5
10.0
14.5 14.0 14.0 12.0 11.5
64-P LS
9. 5
9.0
9.0
8.0
11.5 11.0
11.0
9.5
64-P-L
15.0
14.5
14.5 12.5
19.0 18.5 18.5 16.5 16.0
64-P-L LS
11.5
11.0
11.0
9.5
14.0 13.5 13.5 12.0 11.5
80-P
15.0
14.5
14.0 12.0
18.5 18.0
17 .5 15.5 13.5
80-P LS
11.0
10.5
10.5
9.0
13.5 13.0 13.0 11.5 11.0
80-P-L
18.0
17 .5
17 .5 15.0
22.0 21.0 21.0 19.0 18.0
80-P-L LS
13.0
12.5
12.0
11.0
17.0 16.5 16.0 14.0 13.5
102-P
14.0
13.5
13.0
11.5
17.0 16.5 16.0 14.0 13.5
102-P LS
11.0
10.5
10.5
9.5
13.5 13.0 13.0 12.0 11.5
102-P-L
17 .5
17 .0
16.5 15.0
21.5 21.0 20.5 18.5 17.5
102-P-L LS 15.0
14.5
14.5 13.0
18.5 18.0 18.0 16.0 15.0
122-P
16.0
15.5
15.5
14.0
19.5 19.0 18.5 17.0 16.0
122-P-L
21.0
20.5
20.0
17 .5
26.0 25.5 25.0 22.5 21.5
146-P
15.5
15.0
14.5 13.0
19.0 18.5 18.0 16.0 15.5
Notes:
*LS = Low speed.
**PL = Model P low final temperature model with all air ports open.
Figures in bold face show maximum mounting height with louver cone diffusers set vertically.
To meet CSA and OSHA requirements, Model P Unit Heaters mounted lower than 8.0 ft. from the floor must be equipped with
an OSHA fan guard. Above table based on 60 F entering air temperature. In providing for the use of diffusers, it must be
remembered that adjustment of a LCD to deflect air toward horizontal immediately lowers the mounting height limit.
UH-PRC001-EN
Selection
Procedure
Unit
Steam Pressure (PSI)
75
Size
2
8.0
146-P-L
18.0
17 .5
22.5 22.0 21.5 18.5 18.0
8.0
166-P
18.0
17 .5
8.0
22.5 22.0 21.5 19.0 18.0
9.5
166-P-L
22.0
21.5
27.5 27.0 26.5 23.5 22.5
8.0
202-P
22.0
21.5
8.5
27.5 27.0 26.5 24.0 23.0
9.5
202-P-L
25.5
250
31.5 31.0 30.5 27.0 26.0
8.0
252-P
20.0
19.5
9.0
25.0 24.0 23.5 20.5 19.5
12.0
252-P-L
24.0
23.5
29.5 28.5 28.0 24.5 23.5
8.0
280-P
21.0
20.5
26.0 25.5 25.0 22.0 21.0
4.5
280-P-L
25.5
25.0
32.0 31.0 30.0 26.0 25.0
8.5
336-P
24.0
23.0
30.0 29.0 28.0 25.0 24.0
14.0
336-P-L
29.0
28.5
36.0 35.0 34.0 30.0 29.0
10.5
384-P
28.5
28.0
35.5 35.0 34.0 30.0 29.0
11.0
384-P-L
32.5
31.5
41.0 40.0 39.0 35.0 33.5
9.0
500-P
29.5
29.0
36.5 36.0 35.5 32.0 30.5
14.5
500-P-L
35.0
34.0
43.5 42.5 41.5 35.0 34.0
12.5
600-P
34.0
33.0
42.5 41.5 40.5 36.0 34.5
13.5
600-P-L
37 .0
36.0
46.5 45.5 44.5 39.0 37.0
17 .0
720-P
38.5
37 .5
48.0 47.0 46.0 40.0 39.0
12.0
720-P-L
42.5
41.5
53.0 52.0 51.0 44.0 42.0
Hot Water Selection Example
Selection Procedure
Select the proper size of unit heater for
5
10
50
75
whatever application desired, as
17 .5 15.0
14.0
illustrated by the following examples.
17 .0 14.5
14.0
Example 1:
Select a Model S horizontal unit heater to
21.0 18.5
17 .5
deliver 95 MBH with 220°F entering
21.0 18.5
17 .5
water temperature (EWT), 70°F entering
air temperature (EAT) and a 30°F water
24.5 22.0
21.0
temperature drop (WTD).
19.0
17 .0
16.0
23.0 20.0
19.0
Step 1.
Determine GPM:
20.0
17 .5
17 .0
GPM = Btu/hr
24.5
21.0
20.0
22.0 20.0
19.0
Step 2.
28.0 25.0
24.0
Refer to Table SP-11 to select the
27 .5 24.0
23.0
conversion factor at 220° EWT and 70°
EAT . Factor is 1.058.
30.5
27 .5
26.5
28.5 25.0
24.0
Step 3.
Determine equivalent MBH at standard
33.0 29.0
28.0
conditions (200° EWT , 60° EAT).
32.0 28.0
27 .0
Equiv. MBH = MBH = 95 = 89.8
35.0
31.0
30.0
Step 4.
36.5 32.0
30.5
Select unit size by entering the hot water
40.5 35.0
33.5
tables at the 200 °F EWT column. Select
the unit which will provide 89.8 MBH at
6.53 GPM. In this example, the selection
indicates a Model S 126W2 unit heater,
from Table PD-2, page 28.
To determine the actual capacity of this
Model S 126W2 at operating conditions
(220° EWT and 70° EAT) proceed as
follows.
Step 1.
Determine the MBH at 6.53 GPM by
interpolation in the 200° column. (In this
case 90.8 MBH.) Multiply this MBH by the
conversion factor 90.8 MBH x 1.058 = 96
MBH.
Step 2.
The GPM remains constant = 6.53 GPM.
Step 3.
Calculate the water temperature drop
WTD =
= 95000 = 6.53
(485) WTD 485 x 30
Factor 1.058
Btu/hr
=
96000 = 30.3
GPM x 485
(6.53) (485)
19
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