Technical Article #2 - Whirlpool Baths

Whirlpool baths are also called jetted bathtubs, hydromassage bathtubs and hydromassage therapeutic bathtubs. We think of a whirlpool bath as an ordinary bathtub with some fancy accessories. Incidentally, most makers of whirlpool baths also make their tubs without the whirlpool features. They call these ordinary tubs soakers.

Components and materials

The tub itself is typically an acrylic surface over a fiberglass-reinforced polyester resin backup structure. These fixtures are typically vacuum molded.

Whirlpool baths have a pump that may be ½ to 1 ½ horsepower. These pumps are designed to be self draining to prevent the water becoming stagnant in the pump. The pumps should be accessible through an access cover, although often they are not. The pump is powered by a grounded 120-volt electrical circuit protected by a ground-fault circuit interrupter.

The pumps on whirlpool baths should never be operated unless the jets are completely submerged with water. Some pumps have built-in protection against running dry. Other systems have a low water sensor which is typically a metal disk on the wall of the tub. This sensor will not let the pump run if there is no water.

There is a circulating piping system that is usually made of PVC. There is a suction inlet in the tub and suction piping carrying water to the pump. There is also supply piping coming from the pump to the jets in the tub. There can be four, six or more jets. This piping is designed to be self-draining.

There is an air induction piping system which, again, typically uses PVC plastic pipe. The air induction system has openings, usually at the top of the tub, to draw air in. This air is drawn into the circulating water piping system and discharged with the water through the jets. It is the air that makes the bubbles. The tub also has air induction controls. These are typically dials or knobs on the top of the tub. Opening the air induction controls allows more air to be drawn in and results in more bubbling through the jets. Closing the air induction controls down gives more of a pure water jet and less bubbles. The supply jets at the whirlpool bath are typically adjustable in direction and sometimes in volume.

The controls for the pump may be on the tub or on a wall in the bathroom. If the controls are electric, they usually have to be on the wall in the bathroom, 3 feet from the tub. We don’t want wet people handling electrics. Many tubs have special (some are pneumatic) switches on the tub that are safe to operate when wet.

The pump controls usually are timed for a 10-to 30- minute run cycle. The pump will shut off when the timer expires.

Some systems have a vacuum breaker on the hot and cold supply plumbing to prevent a cross connection. Vacuum breakers may be required by the manufacturer or local authority.

Whirlpool baths have hot and cold supply piping just like conventional bathtubs. They also have conventional drain piping and overflows just like conventional tubs. Some whirlpool baths have a hand held-shower faucet mounted on the top of the tub that can be extended for washing.

Many tubs have fixed or removable skirts on the front. The removable skirts are typically held in place with clips or hook-and-loop fasteners.

Capacity

Whirlpool bathtubs may hold 35 gallons or as much as 150 gallons. Some whirlpool baths are designed for more than one person. These systems can create tremendous loads on the floor. The very large tubs can weigh up to 1,500 pounds when filled with water. The strength of the floor may have to be from 50 to 150 pounds per square foot (psf), depending on the whirlpool bath size. Special consideration may have to be given since common floor framing in houses is designed for 40 psf, and in some cases, 30 psf loads.

Given that whirlpool baths can use huge amounts of domestic hot water, larger or second water heaters have to be provided in many cases. Some whirlpool bath manufacturers recommend storage of up to 100 gallons of hot water.

Installation issues

Whirlpool baths should always be installed level and should be firmly supported. Many have an integral wood base that should be fully supported by the floor system. Most whirlpool baths are not designed to be supported by their rims. The rims should be supported, but should not be expected to carry the weight of the tub.

When ceramic or marble tile is brought up tight to the tub, we want to ensure that water spilled or splashed onto the tile won’t create a concealed leak and concealed water damage.

Most manufacturers and authorities call for an access panel to get at the pump for the tub. Panels of 18 inches by 18 inches or 12 inches by 24 inches are commonly required. The pump itself should be located above the weir of the trap for the tub. This isn’t usually a problem. The pumps are usually fastened to the integral wood base for the tub, although some pumps are shipped separately. Some pumps can also be removed and relocated. Inside the service panel, there is sometimes a service disconnect. This is a convenience item, but not usually required. In some cases, the tub itself is set in a bed of mortar or plaster for improved support. A sheet of polyethylene is often used to separate the tub from the mortar bed.

Operation

Whirlpool baths should be filled at least 1 to 3 inches above the jets with a mix of hot and cold water. (Some people recommend not using straight hot water because of possible discoloration of the acrylic.) The pump should not be operated if all the jets are not submerged. The jets should be at least partly open when the pump is turned on. It’s very hard on the pump if all the jets are closed. A timer device is usually the activation system for a pump.

When the pump is turned on, water is drawn in through the suction inlet and discharged at the jets. The amount of bubbling is controlled by the position of the air induction inlets. The direction of water coming out of the jets can be adjusted by moving the jets. On some models, the flow rate through the jets can be adjusted as well.

Health issues

There are some health issues surrounding whirlpool baths. Some water remains in the piping and the pump, even though these systems are generally described as self-draining. When this water combines with dirt, soap scum, hair, body secretions, skin and bath oils, for example, we can get some pretty interesting bacteria growth. The level of concern varies widely among specialists. You’ll want to check with local authorities to determine whether they have special requirements. Some manufacturers of whirlpools recommend cleaning every three months. The cleaning may consist of using dishwasher detergent (or special low suds cleansing agents) in the tub and activating the whirlpool function. Others recommend the use of vinegar, bleach or baking soda. Still others say this should be done after every use and supplemented by annual professional cleaning.

One of the concerns is that the air induction piping is not normally submerged with water, although it can get wet. Cleaning, using the method described here, may not be effective in cleaning the air induction piping.

While there doesn’t seem to be consensus on this issue, you may decide to inform clients of the potential issues and let them make their own decisions.

Drowning hazard

There is a concern that people’s hair will get caught in the suction inlets of a whirlpool bath, which could potentially cause them to drown. Actually this has happened, but suction inlets are now designed so that they are less likely to catch the hair and pull someone’s head under water. Now the suction inlets typically have very small openings, less than 1/8-inch diameter. Some suction inlets have been recalled by the manufacturer. Some modern whirlpool baths will reduce the suction pressure if an obstruction on the suction side is sensed. This allows people to pull away from a suction inlet if they inadvertently get caught up in it. You may want to check to see if this is a local issue for systems in your area.

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