From jets to service access
What is the difference between an air bath and a whirlpool bath?
An air bath sends air through its jets; a whirlpool sends water. Kohler describes the air bath as warm air pushed through air jets to make bubbles, and the whirlpool as jets of water for a targeted massage.
One bath can have both. Kohler’s walk-in bath has whirlpool jets and air jets that work individually or together. When a quote says “massage bathtub”, ask whether the system is air, water or both.
| Term | What it means |
|---|---|
| Air bath | A blower pushes air through small jets or holes. |
| Whirlpool | A pump circulates bath water through jets. |
| Combination bath | Both a pump and a blower. |
| Hydromassage bathtub | The term in the titles of ASME A112.19.7/CSA B45.10 and UL 1795. |
How does each system move air or water?
A whirlpool recirculates the bath water; an air bath adds air from outside the tub. The steps follow MTI Baths’ descriptions of its whirlpool system and of air baths.
- Whirlpool: the pump draws water in from the bathing well.
- The pump returns that water through the jets.
- An air control changes how much air is mixed into the water.
- Air bath: a blower generates the air.
- A channel around the tub, or separate air lines, carries the air.
- The air leaves through very small holes or air jets low in the tub.
Jacuzzi’s operating manual says its whirlpool jets use water only when closed and mix in air when open. MTI describes two air-bath layouts: a perimeter channel, or air jets with built-in check valves fed from a manifold.
What equipment comes with each system?
The equipment depends on the model, so read it from the installation guide. Four named examples:
| Guide | Components it lists |
|---|---|
| Kohler whirlpool bath, 1387900-2, M series (220–240 V guide) | Pump, heater, control, backjet and neckjet systems, whirlpool jets, keypad with remote. |
| Kohler heated air bath, 1385106-2 | Blower motor, air piping, check valve on some models, keypad, heated surface. |
| Kohler heated whirlpool and air bath, 1385107-2 | Pump motor, heater on H models, blower motor, whirlpool jets, air piping, air switch, keypad. |
| Jacuzzi Luxury Bath manual | RapidHeat heater standard on Salon Spa models, whose controls have both whirlpool and Pure Air functions. |
Get the model documents before assuming an item is included.
What heating and electrical supply does each system need?
Each named guide states its own supply. Kohler’s 1387900-2 is a 220–240 V guide; its other two are 120 V. Do not infer a heater from the word “whirlpool”: Kohler’s combined guide lists one on H models only.
| Guide | Supply it states | Heater statement |
|---|---|---|
| Kohler whirlpool, 1387900-2 | 220–240 V, 20 A dedicated service; Class A GFCI or RCD. | Helps maintain temperature; off above 104 °F. |
| Kohler heated air bath, 1385106-2 | Two dedicated 120 V, 15 A services; two Class A GFCIs. | Bubble heater on its own service. |
| Kohler whirlpool and air, 1385107-2 | Three dedicated 120 V, 15 A services; three Class A GFCIs. | Heater on H models. |
| Jacuzzi Luxury Bath manual | Pure Air blower: 120 VAC, 15 A, dedicated GFCI circuit. For Salon Spa wiring, read the manual’s wiring diagram for the model ordered. | Helps maintain; works at 77 °F or above. |
MTI’s Designer Collection manual asks for dedicated 110 V circuits and says of its in-line heaters: “They are not designed to heat cooled or cold water.” Aquatic’s Millennium Series manual also describes a maintenance heater. This guide gives no wiring instruction; confirm electrical work with the local authority.
Which standards cover whirlpool and air baths?
Two published standards have jetted baths in their scope; only the ASME/CSA scope names air-jetted bathtubs.
ASME A112.19.7/CSA B45.10
The current edition listed by CSA Group is ASME A112.19.7-2020/CSA B45.10:20, reaffirmed in 2025; it supersedes the 2012 edition. Its published scope: general requirements, test methods and markings for whirlpool and air-jetted bathtubs and suction fittings used in hydromassage bathtub systems that incorporate a bathtub and circulation pump.
UL 1795
Edition 6, dated 27 February 2025, has a published scope of indoor hydromassage bathtubs rated 250 volts or less, for household and commercial use, permanently connected to the building plumbing. It excludes portable cord-connected equipment and hydrotherapy tubs.
Suction fitting
A 1994 CPSC notice says whirlpool baths typically have one or two suction openings that draw in water. It announced one maker’s voluntary recall of suction covers made before voluntary industry standards took effect in 1985, because hair could be caught. Kohler’s whirlpool guide, MTI and Jacuzzi each say not to run the unit without the cover.
- The standard and edition named
- Who certified or listed the model
- The marking on the unit
- The suction cover fitted
What access and air space does the equipment need?
The named guides require service access to the pump or blower and, for blowers, air space.
Access panel
Kohler asks for a panel at least 20 in wide by 15 in high on its whirlpool, and 30 in by 15 in on its heated air bath and combined bath. MTI asks for access to each electrical component, at least 16 in by 14 in for most of its systems.
Air space
Kohler’s heated air bath guide calls for ventilation and at least 15 cubic feet of open air space, with the blower motor at least 1 in from a wall. Its combined guide gives 32 cubic feet.
Test before closing in
MTI requires a water test for level, leaks and operation before final enclosure. Kohler has the installer fill above the highest jet, run the bath for 5 minutes and check for leaks.
Aquatic states that installation accounts for as much as 50% of a tub’s operating quietness.
What drying and cleaning does each system need?
The named makers give a drying cycle for the air system and a cleaning interval, and their figures differ:
| Source | What it says |
|---|---|
| Kohler air bath guides | Purge runs the blower for 5 minutes after the unit is off and drained. |
| Jacuzzi manual | One-minute drying cycle 20 minutes after the blower shuts off. |
| MTI white paper | Blowing out an air channel does not clean it or remove residue. |
| Kohler article | Clean the jets of a jetted tub twice a month. |
| Jacuzzi manual | Clean at least twice a month; no oil or oil-based additives. |
| MTI manual | Clean whirlpools at least monthly, at most 90 days apart; no heavy bath oils. |
How should a buyer specify an active bath system?
Start from what the bather wants, then fix the equipment and the room around it.
- Decide the function. A quiet soak, air bubbles, water jets or both.
- Name the system. Write air bath, whirlpool or combination, not “massage bathtub”.
- List the equipment. Pump, blower, heater, controls and jets, by model.
- Fix the electrical supply. Voltage, circuits and protection, from the guide.
- Plan access and air space. Panel size and position before the surround is built.
- Record the standard. Standard, edition and certifier for the model.
- Plan care. Drying cycle, cleaning interval and allowed additives.
When a photo is the only evidence
A photo shows jets, not the equipment behind the panel. Ask for the installation guide of the exact model.
What should you send and ask before a quotation?
A complete request names the active system, not just the tub.
| Question | Why it matters |
|---|---|
| Is the system air, water or both? | Each uses different equipment. |
| Which components are factory-installed? | Lists differ by model and series. |
| Is a heater included, and what does it do? | Named heaters maintain; not on every model. |
| What supply and how many circuits? | From one to three in the guides read here. |
| What access and air space are needed? | Panel sizes differ by guide. |
| Which standard is the model listed to? | Check with the certifier. |
Include with your request
- Function wanted: soak, air, water or both
- Installation type and surround design
- Electrical supply available on site
- Project location and adopted codes
- Quantity per room type
WNS Global confirms any offered bathtub, active system and commercial terms separately in writing. This guide does not state that WNS Global offers air or whirlpool systems, or that WNS Global products have any feature, rating or listing named above.
