Tips for Specifying Whirlpools

To specify the best whirlpool for your client, you should be familiar with the individual mechanical elements of a whirlpool system.

The pump is at the heart of the system. The size varies in horsepower rating from 1/2 hp to 1-1/2 hp. However, this rating is not the only contributing factor to the engineering of the pump and jet system. Therefore, rely on the gallons per minute of water flow pushed through the jets when evaluating the system, rather than simply focusing on the pump horsepower rating. Generally, the whirlpool bathtubs are capable of delivering 5 to 7 gallons (18 to 27 liters) of water per minute, per jet. The system should have UL approved components. Manufacturers typically have the entire system UL-approved for additional safety assurance and for customer satisfaction.

Activator and Switches

Older systems may be activated by a timer switch installed on the wall. If used, locate it out of reach of the bather when he or she is in the tub (most codes call for 39” or 60” of distance from the switch to the bathtub) so the chance of an electrical accident is eliminated.

Alternatively, an air switch installed directly on the bathtub may be available. Check the price list—this type of starter may carry an extra charge. When an air switch is depressed, it increases the air pressure and a bubble of air travels down a length of tube to an electrical switch at the pump. For both safety and convenience, the air switch is superior to an electrical switch.
A third type of switch is available on luxury bathtubs called a “capacitance level switch.” With this type, the sensor operates in a manner similar to a simple capacitor. In the bathtub application, the switch senses the electrical differences that occur when a person lightly touches the control panel and turns the system on.


Both 120- and 240-volt pumps are available. Generally, whirlpool bathtubs with a 1 hp motor or less will operate off a 120-volt circuit. Whirlpool bathtubs that have a motor larger than 1 hp will generally require a 240-volt circuit. Regardless of the motor size, if an in-line heater is included, a 240-volt circuit may be needed.

Holding the Temperature

An “in-line heater” can be added to keep the hot water temperature constant. These heaters do not raise the water temperature.

Do not confuse the purpose of an in-line heater with that of a storage tank or a tankless water heater. The purpose of the tank or tankless water heater is to heat water before it enters the bathtub at the start of the bath. The in-line heater simply maintains the water temperature in the bathtub during the hydromassage bath.

An in-line heater is a good enhancement for a whirlpool tub that will be used by family members for an extended period of time. Just as the piping and pump require service access, such a heater should be reachable to repairmen in the future. Make sure you also have enough electrical power for the 240-volt circuit this heater will require.

Bacteria Growth

New antimicrobial technologies are used by whirlpool bathtub manufacturers today to minimize the growth of bacteria in whirlpool piping. In some cases, the material is applied to the piping as a coating; in other instances, the inhibitor is actually part of the whirlpool piping system. In all cases, the end goal is to inhibit mold, mildew and bacteria growth in the plumbing piping.

Today, manufacturers have designed their whirlpool systems to ensure a completed drain of all water in the piping; therefore, no standing water remains between uses. Additionally, some systems have an automatic purge cycle set by the user, which blows warm air through the piping system at the same time each day to further inhibit any moisture remaining in the piping.

Be sure to alert your clients to the noise level of all whirlpool systems. The majority of the noise is caused as the large volume of water is pushed through the piping and into the bathtub. Therefore, you cannot design a silent system. However, you can minimize the noise by mounting the pump on a thick rubber block and enclosing it on three sides.

There are two different approaches to whirlpool jet design:

  • Fewer jets with larger outlets that are serviced by bigger water lines. The jets operate on a high-volume, low-pressure system that provides a comfortable bathing experience for the user as softly pulsating water rolls around the body. They are generally noisier than the next option.
  • More jets with smaller outlets serviced by small water lines. These jets operate on a low-volume, high-pressure system to bring the water to the numerous jets, which can be individually adjusted for the user’s comfort.

Better systems inject the air into the water, thereby providing a complete mixture of air and water for a more effective massage. To maximize the flexibility of the system, better bathtubs have jets that are individually controlled for spray direction, volume and air/water mixture. The jets in well-engineered bathtubs are also nearly flush to the bathtub’s interior.