pentair-catalog-2025-2026-digital-1-compressed

HEATER SIZING INFORMATION ENGINEERING DATA

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.

MASTERTEMP AND MAX-E -THERM MODEL REQUIRED TO HEAT POOL IN 24 HOURS

Pool Sizing *

Pool Volume (Gallons)

o F Temperature Change/24 Hrs.

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 42,605 48,691 60,864 73,037 97,383 1,034 1,182 1,478 1,773 2,364

10 15 20 25 30 35 40

28,403 32,461 40,576 48,692 64,922 690 788

985 739 591 493 423 369

1,182 1,576

21,303 24,346 30,433 36,519 48,691 17,042 19,477 24,346 29,216 29,216

517 591 414 473

887 710 591 507 443

1,182

945 788 675 591

14,201 16,230 20,288 24,345 32,461 345 394 12,173 13,912 17,390 20,868 27,824 296 338 10,651 12,173 15,216 18,260 24,346 259 295

MASTERTEMP AND MAX-E -THERM MODEL REQUIRED TO HEAT THE SPA 30°F IN A GIVEN TIME PERIOD

Spa Sizing *

Spa Volume (Gallons)

Model

200

300

400

500

600

700

800

900

1000

Minutes for 30 o F Temperature Rise (Heater Input in 1000 BTU/HR)

174 200

21.0 18.0

31.0 27.0 23.5 20.0 13.0

40.0 35.0 30.8 26.5 18.0

50.0 44.0 38.5 33.0 22.0

61.0 53.0 46.5 40.0 27.0

71.0 62.0 54.3 46.5 31.0

81.0 71.0 62.0 53.0 35.0

91.0 80.0 70.0 60.0 40.0

102.0

89.0 77.8 66.5 44.0

250/250HD 15.8

300

13.5

400/400HD

9.0

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.

= Vol. in Gal. x 8.34 lb./gal. x temprise

TIME IN HOURS

* For Commercial Heaters 500,000 BTU/hr and over please contact factory for sizing.

Heater BTUH input x efficiency of heater

POOL & SPA

Vol. in Gal. x 8.34 lb./gal. x temprise x 60 min Heater BTUH input x efficiency of heater

TIME IN MINUTES =

SPA

534

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