Commercial SPA Blower Selection Guide

Posted by Optimal Tech on

Due to the amount of information included in this article we have provided a breakdown of the information below.

  • Installation of Rotron Blower
    • Requirements
      • Number of Jets Chart
      • Recommended SPA Chart
      • System Requirement per Motor Chart
  • Sizing Air Agitation Unit Overview
    • Open Hole Area Formula
    • Water Depth/Open Hole Blower Selection Chart 
  • Rotron Ready Spa Solutions Overview
    • Features and Options
    • Available Accessories 
  • Rotron Ready Spa Solutions Options
    • Dimension Chart 
      • With Links to Available Rotrons
    • Specifications Chart
      • With Links to Available Rotrons
    • Final Notes

SPA System Requirements

There are many variables that must be considered when selecting a blower for spa agitation. The depth of the spa, the size, quantity and location of the air holes and/or jets, and the size and length of the supply line are all important. The requirements of each and every system can be precisely calculated, but this is a long and tedious process. By defining and limiting several of the system parameters, a “standard” selection chart can be created. Blower Selection Chart 1 gives the maximum spa size that can be supplied by each blower.

Hartford Loop Installation
1. Determine the following: Distance from blower to spa (for friction loss calculation), pipe size, power available, and whether or not low-pressure check valve available or Hartford loop is present. Note if water is present in the pipes, the blower has to push water out prior to bubbling. This creates a low-flow situation with the blower. A relief valve and pressure gauge are suggested in this case.
2. If standard commercial venturi driven jets are used and typical system requirements are met, use Chart 1 below.
3. If holes are used, size blower based on Chart 3 below. The chart is based on water depth of 20”. If deeper, use open hole charts and recalculate. Deeper water requires more pressure.
 Blower Size Number of Jets
DR404 (1 HP) 3-6
DR513 (1.5 HP) 5-10
DR454 (1.5 HP) 5-10
DR505 (2 HP) 8-12
DR656 (3 HP) 12-17
Chart 2 - Blower Selection
Max Recommended SPA Surface Area
 Spa Depth DR404 (1HP) DR513 (1.5HP) DR454 (1.5HP) DR505 (2HP) DR656 (2HP)


60 SQ FT 74 SQ FT 88 SQ FT 100 SQ FT 135 SQ FT
36" 50 SQ FT 68 SQ FT 82 SQ FT 95 SQ FT 125 SQ FT
42" 45 SQ FT 64 SQ FT 76 SQ FT 90 SQ FT 115 SQ FT
48" 0 SQ FT 58 SQ FT 68 SQ FT 85 SQ FT 110 SQ FT


Chart 3 - Drilled Holes
System Requirements by Blower Size

 All Blowers Listed Supply and bubbler pipe to be 2.0 inch
l.D. or greater. Supply pipe to be no
longer than 25 ft. with no more than
six elbows.
DR404/DR513 Total hole area must be 1.0 square
inches or greater but not greater than
the cross section of the supply pipe.
DR454 Total hole area must be 1.5 square
inches or greater but not greater than
the cross section of the supply pipe.
DR505 Total hole area must be 2.0 square
inches or greater but not greater than
the cross section of the supply pipe.
DR656 Total hole area must be 2.4 square
inches or greater but not greater than
the cross section of the supply pipe.

Total hole area = (number of holes) X (.785) X (hole diameter)2 or
Total hole area = (number of holes) X (hole area)


The open hole charts provide a quick and easy method of sizing a spa blower. The chart is used when holes (not jets) are used. Simply find the total open hole area (see formula below), and then with the water depth in inches (Y axis of the chart), move across the chart until the water depth intersects with the total open hole area curve and find the blower that is closest to the intersection of water depth and open hole area.

Total open hole area (in square inches) = # of holes X ( 3.14 X (diameter) X (diameter) ) / 4

ie. a spa with twenty 1/4” dia holes has an open hole area of .98 sq inches.

Ex. A spa with water 40 inches deep, with twenty 1/4” diameter holes would require a DR656 blower

 ROTRON Ready SPA Solutions 

• Manufactured in the USA-ISO 9001 and NAFTA compliant
• CE Compliant-Declaration of Conformity on file
• Maximum Flow: 105, 127, 160, 200 or 78 SCFM
• Maximum Pressure: 56, 58, 74, 69, 88 IWG
• Standard Motor: 1.0, 1.5, 2.0, 3.0 HP, SPA Duty ODP
• Cast aluminum blower housing, impeller & cover; cast iron flanges (Threaded)
• Approved motor with permanently sealed ball bearings and Class B rated thermal protection
• Inlet and outlet internal muffling
• Quiet operation within OSHA standards

• Internal voltage and frequency (Hz)
• Chemical-duty, high-efficiency, inverter-duty or industry-specific designs
• Various horsepower for application-specific needs

• Corrosion-resistant surface treatments and sealing options
• Slip-on or face flanges for application-specific needs


Filtration Inline filter Protect blower from dust and airborne contaminants
Measurement Air Flow Meter Optimize Efficiency
Noise Reduction Inlet/Outlet Muffler (Single Connection) Lower blower noise for pressure and vacuum systems
Valves and Gauges Pressure Regulating Diaphragm Valve Prevent excessive system pressure or vacuum that could result from line restrictions
 Valves and Gauges Pressure Regulating Diaphragm Valve Prevent excessive system pressure or vacuum that could result from line restrictions


ROTRON Ready Spa Solutions

 Dimension Chart

  DR404AQ58M DR454V58 DR505AW58M DR513V58 DR656K58X
A(IN/MM) 4.75/120.7 4.75/120.7 4.75/120.7 4.75/120.7 4.92/125
B(IN/MM) 8.93/226.8 10.30/231.6 10.30/231.6 11.42/290.1 11.42/290.1
C(IN/MM) 10.12/257 11.39/289.1 11.70/298.2 13.0/330.2 12.8/325.1
D(IN/MM) 1.92/48.8 1.92/48.8 1.87/47.5 2.23/56.6 2.25/57.2
E(IN/MM) 6.28/159.5 6.98/177.3 7.26/184.4 8.69/220.7 7.46/189.5
F(IN/MM) 11.5/292.1 12.55/318.8 13.53/343.7 12.21/360.9 15.42/391.7
G(IN/MM) 12.16/308.9 13.52/343.4 14.38/365.3 15.8/401.3 15.17/385.3
H(IN/MM) 3.0/76.2 3.25/82.6 3.56/92.7 3.72/94.5 4.14/105.2
I(IN/MM) 3.75/95.3 4.50/114.3 4.50/114.3 5.50/139.7 5.50/139.7
J(IN/MM) 12.88/372.2 10.81/274.6 14.38/365.3 13.74/349 15.12/384.1
K(IN/MM) .59/15 .59/15 .59/15 .59/15 .59/15
L(IN/MM) 12.91/327.9 14.45/367 15.0/381 14.58/370.3 15.51/393.9


Specification Chart

  DR404AQ58M DR454V58M DR505AW58M DR513V58 DR656K58X
Specification Units 037778 080485 037935 038143 080603
Motor Enclosure - Shaft MTl - SPA(ODP)- CS SPA(ODP)- CS SPA(ODP)- CS SPA(ODP)- CS TEFC-CS
Horsepower - 1.0 1.5 2.0 1.5 3.0
Voltage AC 115/230 115/230 115/230 115/230 115/230
Phase - Single Single Single Single Single
Frequency - 50/60 Hz 50/60 Hz 50/60 Hz 50/60 Hz 50/60 Hz
Insulation Class - F F F F F
NEMA Rated Motor Amps Amp(A) 15/7.5 15.2/7.6 17.6/8.8 15.2/7.6 31/15.5
Service Factor - 1.4 1.3 1.2 1.3 1.0
Maximum Blower Amps Amp(A) 8/4 17/8.5 26/13 17/8.5 27.8/13.9
Locked Rotor Amps Amp(A) 32/16 85/43 106/53 85/43 200/100
Recommended NEMA Start r Size 0/00 1/0 1/0 1/0 1.5/1
Shipping Weight  LBS/KG 64/29 76/34.5 83/37.6 90/40.8 51/23.1
Recomended Number of Jets ts- 3-6 5-10 5-10 12-17 8-12


Voltage - ROTRON motors are designed to handle a broad range of world voltages and power supply variations. Our dual voltage 3 phase motors are
factory tested and certified to operate on both 208-230/415-460 VAC-3 ph-60
Hz and 190-208/380-415 VAC-3 ph-50 Hz. Our voltage 1 phase motors are
factory tested and certified to operate on both 104-115/208-230 VAC-1 ph-60
Hz and 100-110/200-220 VAC-1 ph-50 Hz. All voltages above can handle a
±10% voltage fluctuation.

Special wound motors can be ordered for voltages outside our certified range.

Operating Temperatures - Maximum operating temperature: Motor
winding temperature (winding rise plus ambient) should not exceed 140°C
for Class F-rated motors or 120°C for Class B-rated motors. Blower outlet air
temperature should not exceed 140°C (air temperature rise plus inlet temperature).
Performance curve maximum pressure and suction points are based
on a 40°C inlet and ambient temperature. Consult factory for inlet or ambient
temperatures above 40°C.

Maximum Blower Amps - Corresponds to the performance point at which
the motor or blower temperature rise with a 40°C inlet and/or ambient
temperature reaches the maximum operating temperature.

- The blower should not be stopped/started more than four times an hour.
- Use of relief valve 515092 is required for all blowers 2 HP or greater.


Information provided by Ametek DFS


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