The plumbing of the hot tub consists of: A pressure system delivering water to the jets A suction system returning water to the pumps. 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. 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. Heating and energy use[ edit ] Hot tubs are usually heated using an electric or natural gas heater, though there are also submersible wood fire hot tub heaters, as well as solar hot water systems.
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. Effective insulation greatly improves the energy efficiency of a hot tub. There are several different styles of hot tub insulation: Many manufacturers advertise the superiority of their approach to insulation, but few independent side-by-side comparisons are available.
The hot tub 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. Some covers are better for insulation and therefore are lighter on internal parts and energy efficiency. Some examples of covers are insulated, aluminum, rolling, or a tonneau.
Swimming pool sanitation Since hot tubs are not drained after each use it is necessary to treat the water to keep it attractive and safe. It must be neither too alkaline nor too acidic, and must be sanitised to stay free of harmful microorganisms.
Partly due to their high water temperatures, hot tubs can pose particular health risks if not regularly maintained: Hot tubs should also be periodically shocked, which means oxidizing or breaking down organic material left behind from the sanitizer, as well as non-filterable material such as soap films and perspiration.
For aesthetic reasons, and for the sanitizer to work properly, water should be neither too alkaline nor too acidic low pH. The hardness level of the water, measured as the amount of dissolved calcium, is also important. Insufficient hardness can lead to corrosion and water foaming. They have molded seating. They typically can seat two to seven persons or more.
Wooden hot tubs are often made of redwood or cedar and assembled from vertical staves and the structure is held together like wooden barrels, with metal bands.
A temperature of 37 degrees is considered safe for a healthy adult. Soaking in water above 39 degrees Celsius can cause fetal damage during the first three months of pregnancy. The greater danger associated with electrical shock in the water is that the person may be rendered immobile and unable to rescue themselves or to call for help and then drown.
In the same period 18 incidents were reported to the CPSC involving body part entrapment. To reduce the risk of entrapment, US safety standards require that each spa have two intakes for each pump, reducing the amount of suction.
Disease risk[ edit ] Poorly santised hot-tubs have been linked to a number of diseases, principally caused by facultative aerobic bacteria.
Such incidents include hot tub folliculitis and legionellosis.