The Science Behind Hot Tubs: How They Are Engineered
A hot tub, sometimes called a home spa or Jacuzzi, is a large tub or water-filled enclosure that is heated and maintained at a desirable temperature. Made for relaxation and hydrotherapy, because most have jetted therapy, they are a popular with people of all ages. They are generally located outdoors, or under a canopy or gazebo and can accommodate multiple users, depending upon their size. They are somewhat comparable to swimming pools as far as upkeep and maintenance but are on a much smaller scale and can be moved when empty. The science behind hot tubs is rather simple, considering the components they use and the maintenance required to keep them working properly.
The major component, is the hot tub body, usually made of fiberglass, vinyl, acrylic, cement or wood in the shape of a circle or rectangle. A pump provides pressure via reinforced hoses to the interior water jets, while at the same time, a suction systems retrieves the water and recycles it. A filter is normally located in the hose system to trap debris and particles. The filter can be inline or part of a separate pump system which acts independently, either running constantly, or during timed settings. An air induction system is provided to compress the water stream and this produces a stronger water massage effect. Sometimes an air blower is used to create the agitated bubbly effect. Some hot tub systems use an ozone activator which helps to clean the water and remove harmful minerals and chemicals, depending upon the sophistication of the model. Most hot tubs use either an electric or gas operated heater, controlled by a thermostat which raises and maintains the water temperature.
Physics and Science
Water is supplied to the hot tub water pump from an outside source. The hot tub pump’s impeller rotates at a high rpm, forcing water through the intake hose at moderate pressure to a heating device. The heater excites the water molecules, actually making them move faster, thus creating a higher temperature. The heated water is then directed to the jets through a valve diverter box which branches off to several lines. The lines lead to several discharge jets on the inside of the tub. Bullfrog Spas, actually utilize about 90% less plumbing than other designs for a much more efficient system. The discharge jets have a Venturi design that constricts the flow of water, compressing it, and speeding it up while pulling in air which further compresses and speeds up the air/water mixture. Depending upon the shape and number of the discharge nozzle openings, a spray or stream is created which causes the familiar massage reaction. The tub water is then sucked through the intake system, filtered, and then pumped through the cycle again. The filter can be before or after the pump, depending upon the configuration of the hot tub model. Covers are routinely used to keep evaporation down, preventing as much as 75 percent of the water loss.
Hot tubs are not drained after use, and must be routinely treated. Sanitation chemicals keeps them free of microorganisms. Prescribed amounts of bromine and chlorine are needed at occasional intervals. The amount of acidity or alkalinity, or pH level, must also be regulated to assist the sanitizer in performing properly. This means the hardness of the water, or amount of calcium must also be kept in check. Contaminants that cannot be filtered such as perspiration and soap films must be removed by oxidation, and this is where a non-chemical ozonator can be beneficial.