E
N
G
I
N
E
E
R
I
N
G
D
A
T
A
612
ENGINEERING DATA
HEATER SIZING INFORMATION
Pool heaters can be sized by the volume method for maintenance heating or for spot heating. For many days during the
swimming season, the sun maintains a desirable pool temperature of 78–80°F. and the pool requires no supplemental
heating. However, during cooler periods a pool will usually lose 2–4°F. per day.
To get the water to the desired temperature, you could choose a smaller heater and run it during the daily filter cycle of 4–6
hours every day. This would be sufficient to overcome a slight temperature drop between filter cycles, but it would mean
leaving the heater on every day. If you don’t use the pool daily, it’s more economical to spot heat the pool, say for the
weekend. In this case, you could choose a larger heater which will heat the pool faster, and then can be turned off between
uses. With either, maintenance heating or spot heating, you need to determine the size of heater to select and the time it will
require to heat the pool.
Pool Sizing *
MASTERTEMP AND MAX-E -THERM MODEL
REQUIRED TO HEAT POOL IN 24 HOURS
o
F Temperature
Change/24 Hrs.
Pool Volume (Gallons)
Model
175
Model
200
Model
250/250HD
Model
300
Model
400/400HD
Model
175
Model
200
Model
250/250HD
Model
300
Model
400/400HD
Pool Capacity in Gallons
Pool Surface Area in Sq. Ft. at 5.5' Depth
5
85.210
97,383
121,729
146,075
194,766
2,069
2,364
2,955
3,546
4,727
10
42,605
48,691
60,864
73,037
97,383
1,034
1,182
1,478
1,773
2,364
15
28,403
32,461
40,576
48,692
64,922
690
788
985
1,182
1,576
20
21,303
24,346
30,433
36,519
48,691
517
591
739
887
1,182
25
17,042
19,477
24,346
29,216
29,216
414
473
591
710
945
30
14,201
16,230
20,288
24,345
32,461
345
394
493
591
788
35
12,173
13,912
17,390
20,868
27,824
296
338
423
507
675
40
10,651
12,173
15,216
18,260
24,346
259
295
369
443
591
MASTERTEMP AND MAX-E -THERM MODEL
REQUIRED TO HEAT THE SPA 30°F IN A GIVEN TIME PERIOD
Spa Sizing *
Note: The chart is based on a 30
o
F (16.6
o
C temperature rise, discounting losses and only based on heat required to raise temperature in minutes.
Two-year limited warranty. See warranty for details.
* ASME models available, Please see your Pentair Aquatic Systems Representative for details.
* ForCommercialHeaters500,000
BTU/hr and over please contact
factory for sizing.
Spa Volume (Gallons)
Model
200
300
400
500
600
700
800
900
1000
Minutes for 30o F Temperature Rise (Heater Input in 1000 BTU/HR)
174
21.0
31.0
40.0
50.0
61.0
71.0
81.0
91.0
102.0
200
18.0
27.0
35.0
44.0
53.0
62.0
71.0
80.0
89.0
250/250HD
15.8
23.5
30.8
38.5
46.5
54.3
62.0
70.0
77.8
300
13.5
20.0
26.5
33.0
40.0
46.5
53.0
60.0
66.5
400/400HD
9.0
13.0
18.0
22.0
27.0
31.0
35.0
40.0
44.0
TIME IN HOURS
=
Vol. in Gal. x 8.34 lb./gal. x temprise
POOL & SPA
Heater BTUH input x efficiency of heater
TIME IN MINUTES
=
Vol. in Gal. x 8.34 lb./gal. x temprise x 60
min
SPA
Heater BTUH input x efficiency of heater
