Whirlpool baths and air baths are tubs with two distinctly different hydrotherapy systems.
Whirlpool baths have been in production the longest. They consist of a bath, a pump, and a plumbing system that runs to jets. Water is delivered to the jets and is most often controlled by turning the jet to control the volume. A typical whirlpool bath will have 6-8 jets, usually with at least one concentrated on the back. Water is pulled from the bath through a suction and circulated into the pump and then to the jets.
Whirlpool systems deliver an intensive level of hydrotherapy. It is considered a muscle therapy, like getting a massage. Whirlpool jets may be too intense for some people because of the extremely focused jets of water. Due to the fact that a whirlpool system is circulating water through pipelines, it must be flushed and sanitized on a regular basis.
Air systems are a much less vigorous type of hydrotherapy. They consist of a series of approximately sixty openings around the bottom perimeter of the bath. These openings are connected to a sealed air channel which is then connected to a blower motor. The blowers typically have a wide range of settings such as 1-99. The blower forces warm air into the bath that creates an effervescent sort of hydrotherapy. It is much more of a skin level effect making it relaxing and easier on areas that might be too sensitive for a standard whirlpool jet.
The air system is much easier to maintain that a whirlpool bath because no water is circulating through the air system. The only concern with water is residual water that drains into the openings and then into the air channel. The air bath will come on 15 minutes after it has been drained and run a one minute purge cycle through the air channel to dry it out.