This article is about the pool. For other uses, see Hot tub (disambiguation).

Hot tub at Big White Ski Resort

A hot tub is a large home-made or manufactured tub or small pool full of heated water and used for soaking, relaxation, massage, or hydrotherapy. Big White Ski Resort, or simply Big White, is a Ski resort located southeast of Kelowna, in the British Columbia interior Recreation or fun is the expenditure of time in a manner designed for therapeutic refreshment of one's Body or Mind. Hydrotherapy, formerly called hydropathy involves the use of Water for soothing pains and treating diseases In most cases, they have jets for massage purposes. Hot tubs are usually located outdoors, and are often sheltered for protection from the elements, as well as for privacy.

There are two different styles of hot tubs:

• Simple wooden-staved soaking tubs
• One piece plastic tubs (usually referred to as spas)

Hot tubs are usually heated using an electric or natural gas heater, though there are also submersible wood-fired heaters, as well as solar hot water systems. Natural gas is a Gaseous Fossil fuel consisting primarily of Methane but including significant quantities of Ethane, Propane, Solar hot water is water heated by the use of Solar energy. Solar heating systems are generally composed of solar Thermal collectors a Fluid Hot tubs are also found at natural hot springs; in this case, the water may be dangerously hot and must be combined with cool water for a safe soaking temperature. A hot spring is a spring that is produced by the emergence of geothermally heated Groundwater from the earth's crust.

Water sanitization is very important in hot tubs, as many organisms thrive in a warm, wet environment. Disinfectants are Antimicrobial agents that are applied to non-living objects to destroy Microorganisms, the process of which is known as disinfection. Maintaining the hot tub water chemistry is also necessary for proper sanitization and to prevent damage to the hot tub.

Of the 130-odd manufacturers in North America in 2005, the top twenty each produced more than 7,000 spas annually. China is quickly becoming the largest supplier of Hot tubs.

Wooden tubs

This style of hot tub is constructed with wooden staves and steel bands, very much like a very large barrel. A barrel or cask is a hollow cylindrical container traditionally made of Wood Staves and bound with Iron Hoops The The staves are usually made of redwood, cedar, or teak, with most older tubs made of redwood. Wooden hot tubs are often quite deep, 36"-48", and can be inset within a wooden deck for ease of entry. Inside the tub, wooden bench seating is common, forming a ring around the inner circumference of the tub.

One Piece Hot Tubs

Using a crane is a common method of installing a one piece hot tub

One piece spas, also known as unibody spas, are formed as one piece with shapes that provide a variety of seating arrangements within the tub. A crane is a lifting machine equipped with a Winder, Wire ropes or Chains and sheaves that can be used both to lift and lower materials and to Each integral seat is often equipped with one or more water jets that allows water to be directed at parts of the body. The water flow may be aerated for additional effect, and some or all of the jets may also automatically move or rotate, providing a massage-like effect. Although wooden tubs were the most common type of hot tub in the 1970s, one-piece hot tubs now dominate the market as they are less expensive to manufacture, easier to install, and more energy efficient. This article is about the Decade 1970-1979 For the Year 1970 see 1970. In America, these kinds of tubs are also incorrectly referred to as Jacuzzi or Whirlpool tubs, though both are brand names.

One piece spas are usually shallower than wooden tubs, usually being 32" to 36" in height to fit through doors and narrow hallways. Cranes are occasionally used to place one piece spas in a backyard or other location that does not have adequate clearance for carrying the tub.

Spas usually have between one and four water pumps, with one circulation pump serving the heating and filtration water loop and the other(s) driving the hydrotherapy jets. A circulator pump is a specific type of Pump used to circulate Gases Liquids or slurries in a closed circuit Sophisticated computer controls are now common and many tubs now are equipped with extensive lighting, sound systems, and even flat panel televisions with DVD players. A computer is a Machine that manipulates data according to a list of instructions. Lighting includes both artificial Light sources such as lamps and natural illumination of interiors from Daylight. Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic DVD (also known as " Digital Versatile Disc " or " Digital Video Disc " - see Etymology)is

Construction of a one-piece spa

The spa shell is the exterior of the tub, and is composed of a surface and an understructure that are bonded together during the manufacturing process. The surface is the source of the color, look and feel of the spa, so it should resist deterioration due to the sun, spa chemicals, or normal wear and tear. Some high-end shells have special coatings to make them more stain resistant or have anti-bacterial ingredients molded into the shell material.

There two primary methods used for manufacturing one piece spa shells:

• vacuum forming of an acrylic base by placing the sheet over a mold and heating with an overhead heater while pulling a vacuum on the mold
• rotational molding: involves placing polyethylene powder in an aluminum mold which is then heated and spun in a large oven so that the plastic melts and takes the form of the mold. Vacuum forming, commonly known as vacuforming, is a simplified version of Thermoforming, whereby a sheet of Plastic is heated to a forming temperature Rotational molding or moulding is a versatile process for creating many kinds of mostly hollow Plastic parts

The understructure of the shell provides the strength needed to support hundreds of gallons of water and the weight of the bathers (the cabinet is not normally part of the weight-bearing structure). The substructure is generally made of FRP (commonly called fiberglass), though some companies use ABS or other plastics. Fiberglass (also called fibreglass and glass fibre see Spelling differences) is material made from extremely fine Fibers of Glass. Acrylonitrile butadiene styrene or ABS, ( Chemical formula (C8H8· C4H6·C3H3Nn is Some manufacturers build a self-supporting shell, while others use secondary supports of wood or metal under the seats or in high-stress areas to reduce the amount of FRP required. Some companies use a perimeter frame of wood or metal to support the rim.

The plumbing of the spa consists of several distinct systems:

1. A pressure system delivering water to the jets
2. A suction system returning water to the pumps.
3. A filtration system - the plumbing has to incorporate a filter system to help clean the water. Some models use a separate small 24/7 filter pump while others use programmed settings of the main pumps.
4. Induced air - The jets may use a venturi effect to incorporate air into the water stream for a lighter massage effect; this requires another set of hoses. The Venturi effect is the fluid pressure that results when an incompressible fluid flows through a constricted section of pipe
5. Some models use an air blower to force air through a separate set of jets for a different "bubbly" massage effect; this is a separate system from the induced air.
6. An ozone system - ozonation is a common adjunct to water maintenance, and if installed will have its own set of hoses and fittings.

The spa cabinet is the skirting around the hot tub, and serves as both an enclosure for the plumbing and a decorative wrap. For many years, spa cabinetry was made of wood, most commonly redwood or cedar, and this is still a popular choice. Wood cabinets require regular maintenance, though, especially in climates where they are exposed to severe weathering. Synthetic materials are increasingly popular because they are seen as requiring relatively little maintenance to keep their appearance.

Energy efficiency

Effective insulation greatly improves the energy efficiency of a spa. There are several different styles of spa insulation: some manufacturers fill the entire cabinet with foam, while others insulate the underside of the shell, the inside of the cabinet, or both. Not surprisingly, many manufacturers advertise the superiority of their approach to insulation, but few independent side-by-side comparisons are available. The spa pump and hot tub heater represent most of the power consumption in a hot tub and vary in use of power depending on their size.

Energy efficiency of the tubs has been studied by the Pacific Gas and Electric Company^[1]. For the 1970s rock music band see Pacific Gas & Electric (band. The industry has responded to the study. ^[2]

After this study, both the California Energy Commission and National Resources Canada have taken an interest in the energy efficiency of portable spas (late 2006).

California's portable electric spa listing include R Values of thermal insulation, and standby watts. The term thermal insulation can refer to materials used to reduce the rate of Heat transfer, or the methods and processes used to reduce heat transfer The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. ^[3][4]

Spa covers have been shown to reduce most if not all of the evaporative losses from the pool when in use. With this component of heat loss being 70% a cover with even a small R-value is able to achieve as much as a 75% reduction in heating costs when used as opposed to leaving the water surface exposed. ^[5]

Alternative Designs

Metal stock tanks have also been used as a cheap alternative for a hot tub, though the lack of insulation makes heating difficult. A stock tank is used to provide Drinking water for animals such as Cattle or Horses. There are also hot tubs that use firm insulation coated in vinyl to hold in water, but these must be short due to the weight of water and the relatively low tensional strength of insulation and vinyl.

Sanitation and chemistry

Maintaining hot tub water sanitation and chemistry is necessary to prevent the spread of disease as well as damage to the tub. In addition to the use of a pump and micrometre-range particulate filter, bromine, chlorine or mineral sanitizers are almost always used as a primary sanitizer, and often supplemented with an ozone generator, UV sterilization, and/or silver and copper ion generator (also known as a "spa ionizer"). Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and Mineral sanitizers for the Swimming pool and Spa use Minerals Metals or elements derived from the natural environment to produce OZONE is an object oriented Operating system written in the C programming language. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays ^[6]

To periodically remove any stubborn microorganisms, or in the event of poor water sanitation, "shocking" the hot tub is recommended. This can be done with either potassium monopersulfate (usually referred to as "non-chlorine shock"), or a relatively large dose of granulated chlorine. The hot tub should not be used for a period of time after starting the shock treatment, typically 15 minutes for potassium monopersulfate and 8 hours for chlorine.

Maintaining the water chemistry involves keeping the pH, total alkalinity, and calcium hardness within acceptable margins. pH is the measure of the acidity or alkalinity of a Solution. If the pH is not maintained in the correct range, chlorine will not be effective at eliminating bacteria. pH is the measure of the acidity or alkalinity of a Solution. Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and ^[7] Also, severe problems with the water chemistry may cause metal parts of the tub's plumbing to corrode, damaging or destroying them. Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings The Langlier Saturation Index is important to determine and maintain properly, so that calcium and magnesium deposits do not form in the water heater

Poor hot tub sanitation, whether by improper design or failure of the sanitation system, can result in disease transmission and litigation. ^[8] It is recommended to have multiple sanitation systems to prevent system failure if one sanitation subsystem fails.

Health Issues

Hot tubs can be dangerous to the health under some circumstances. Studies show that usage may increase miscarriage risk in pregnant women. ^[9] Also, studies show that usage may hurt male fertility. ^[10]

Commonly used terms

Hot tub - name originally given to the earliest tubs that were round, made of wood, and located outdoors; now is commonly used interchangeably with the phrases 'home spa' and 'portable spa'.

Home spa - generally made with a plastic shell; surrounding cabinet may be made of wood or synthetic materials; can be used to describe an above ground, in-ground, indoor or outdoor spa.

Portable hot tub/portable home spa - name for any hot tub/home spa that is pre-assembled and sits above ground; actual size and features of a portable hot tub vary widely, from small portable hot tubs that weigh only a few hundred pounds and plug into a household outlet to large tubs that weigh several thousand pounds and require specific installation methods and electrical wiring.

Stereo systems

Some hot tub models have integrated sound systems. These sound systems are typically made of marine grade components that can withstand the humid environments associated with spas.

See also

• Finnish sauna
• Ofuro
• Sauna
• Steam shower

References