Construction

Some details on the construction and manufacturing process of hot tubs and spa baths.

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.

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. 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.
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.

Copyright © 2008 Orchard Spas

[ Terms & Conditions ] [ Privacy Policy ]