Cover (spa cover)An insulated lid with foam cores. Straps lock it down.
Shell (acrylic shell)Molded acrylic. The seats are formed in it.
Cabinet (skirt)The outer walls. One panel comes off to reach the equipment.
Control panel (topside control)The keypad on the rim. It talks to the control box.
JetShoots pumped water mixed with air. Many jet faces turn.
Jet pump (main pump)Drives water to the jets. Figure B pulls one apart.
The tub, cut away 10
Pillow (headrest)A soft pad for the head. Makers say pillow or headrest.
Air control (air venturi)A rim knob or lever that adds air to the jets.
Diverter (diverter valve)Turning it sends the pump's water to a different set of jets.
Filter cartridgePleated. It lifts out from under the filter lid for cleaning.
Suction fitting (suction cover)Water leaves the tub here on its way to a pump.
Drain valve (spa drain)Empties the tub. Low at the front, outside or behind the panel.
HeaterWarms the water as a pump pushes it through.
Control box (spa pack)The tub's brain. Pumps, heater and keypad plug into it.
Circulation pumpA small quiet pump for constant filtering. Some tubs have none.
Ozonator (ozone generator)Makes ozone that helps clean the water. Often an option.
The pump pulled apart 8
Motor (dry end)The dry end. It turns the impeller and stays out of water.
ImpellerSpins inside the volute and throws the water outward.
Volute (pump casing)The pump casing. The impeller spins inside it.
Pump unionA threaded nut and tailpiece joining pipe to pump. Two per pump.
Intake (suction port)Water enters the pump here, at the center of the impeller.
Discharge (outlet port)Water leaves the pump here, under pressure, toward the jets.
Drain plugUnscrews to let water out of the pump casing.
Pump seal (shaft seal)Seals the spinning shaft so water stays out of the motor.
How this list was compiled: Part names and every detail line were checked, for facts only and with nothing copied, against pages and documents read on 2026-09-20. Wikipedia: https://en.wikipedia.org/wiki/Hot_tub (a cast acrylic shell with molded seating, supported by a frame structure and surrounded by a skirt; a pressure system that feeds the jets and a suction system that returns water to the pumps; some models run a separate small filter pump constantly; jets may use a Venturi effect to add air; some models use an air blower; an ozone system if installed; an electric or natural gas heater; covers) and https://en.wikipedia.org/wiki/Centrifugal_pump (fluid enters the impeller along its axis and is thrown outward into a volute casing; motor shaft). Four hot tub makers' owner's manuals whose texts are independent. Maker A, found from https://www.jacuzzi.com/en-us/hot-tubs/owners/manuals, document https://links.imagerelay.com/cdn/574/ql/51f69868f9dc438eabf98158c06fb128/26-J200-ENG-DOM-L.pdf (control panel, headrest pillows, air controls, suction fittings and suction covers, filter lid with one underlying filter cartridge, filter pleats, jets with an outside jet ring, jets pump, circulation pump, heater, ozone unit, spa shell, synthetic cabinet and cabinet side panels, equipment bay, control box, drain valve, spa cover with foam cores, straps and clip tie downs, footwell). Maker B, found from https://www.hotspring.com/owners/manuals-and-resources/hot-spot, document https://d1oxc6ayqrhsgs.cloudfront.net/hot-spring/hot-spring-hot-spot-collection-owners-manuals-2026.pdf (control panel; the diverter lets you send water to different sets of jets by turning the lever; the air control lever sets the amount of air for the jets; jet pressure is adjusted by rotating the jet's faceplate; pillow; filter compartment and filter cartridges; floor drain and spa drain, the drain valve at the lower front of the spa; spa suction; acrylic spa shell; cabinet and door panel; cover with cover locks and handles, fold back the cover; an equipment compartment holding jet pump, heater, circulation pump, control box, optional ozone injector and drain; the circulation pump is a dedicated quiet pump that provides continuous filtration). Maker C, found from https://calspas.com/owners-manuals/, document https://calspas.com/pdf/owners-manual/Patio%20and%20Patio%20Plus%20Owners%20Manual%202024.pdf (front panel and side panels, equipment area, unions and pump unions, gate valves, drain valve closed and capped, filter cartridge, filter lids, weir, main pump, topside controller, diverter knobs and air venturis as knobs around the top of the spa, heater, ozonator, the words for spas without a circulation pump, pillows and headrests, spa cover with locking tie-downs, acrylic shell, wood frame, spa cabinet, control box). Maker D, found from https://www.bullfrogspas.com/manuals/, document https://www.bullfrogspas.com/wp-content/uploads/2025/04/2025_A-Series-Owners-Manual_v1.7.pdf (numbered overview: main control, removable headrests, interior light, floor drain, suction fitting, filter intake and weir door; numbered equipment compartment: jet pump 1 and 2, control box, ozone, drain outlet, water heater, support stud, acrylic spa shell; circulation pump; PVC pipe unions in the equipment compartment). Two spa pump makers. Pump maker 1, catalogs found from https://waterwayplastics.com/resources/catalog-choices/, https://api.waterwayplastics.com/catalogs/990-1081.0823%20Catalog%20Vol2%20tech.pdf and https://api.waterwayplastics.com/catalogs/990-1081.0823%20Catalog%20Vol2%20spa.pdf (exploded wet end parts lists, front to back: drain plug or air relief plug, faceplate, volute O-ring, wear ring, impeller assembly, pump seal, volute; pump unions of tailpiece, union nut and O-ring; intake and side discharge; motor; split capacitor; distributor manifolds; blowers; no trap or strainer basket on any spa wet end). Pump maker 2, https://geckoalliance.com/wp-content/uploads/2023/01/Pumps_TechSheet_en_9919-101489.pdf, https://geckoalliance.com/products/flo-master-xp2/ and https://geckoalliance.com/wp-content/uploads/2023/01/Flyer_universeal_seal.pdf (pump casing (volute); the impeller seal; motor; two union nuts with slip tail pieces and O-rings; wing nut drain plugs; intake and discharge; the seal's faces ride on the impeller shaft). Trade pages: https://www.spadepot.com/pages/pumps (wet end; the discharge fitting on the wet end; intake; two unions; pump seals; starting capacitor; four through bolts), https://www.spadepot.com/pages/spa-pack-replacement (the control system (spa pack) is the tub's brain; the topside controller talks to it; pumps, blower and heater connect to it), https://www.spadepot.com/pages/how-to-guides-hot-tub-air-blower-replacement (blowers and a PVC manifold), https://www.spadepot.com/pages/spa-leaks (unions, gate or slice valves, jets and manifolds), https://www.spadepot.com/pages/all-about-ozone-in-hot-tubs (ozonator, ozone generator) and https://www.swimuniversity.com/hot-tub-pump/ (every spa pump has two ends, wet and dry; the wet end houses the impeller; the dry end is the motor). Closed or unreachable on 2026-09-20: masterspas.com owner's manuals (HTTP 500), marquisspas.com and sundancespas.com manual pages (404), balboawater.com pump pages (404), hottubworks.com (HTTP 500), blog.intheswim.com (404). No maker is named on the page. Re-checked on 2026-09-30: all 24 names found again in two or more independent sources, each fetched again at the addresses above: Wikipedia's wikitext for Hot tub and Centrifugal pump, the four hot tub makers' owner's manuals, the two pump makers' catalogs and sheets, and the trade pages. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; own work, nothing traced or copied. The two figures stand one above the other on a sheet 1000 by 1240, not side by side in two wide rows as the brief in art describes, so that the sheet fills a phone held upright; what each figure shows is as briefed. Licence: own work
How it works
This parts of a hot tub diagram shows a portable tub cut away from the front, with one cabinet panel off so the equipment bay shows. Below it, the jet pump is pulled apart into its wet end and motor.
Read the full guide
What are the parts of a hot tub called?
Start with six: cover, shell, cabinet, control panel, jet and jet pump. On the rim, an air control adds air to the jets and a diverter sends the pump's water to a different set of them. The equipment bay holds the control box, the heater and the pumps.
What are the parts of a hot tub pump?
A spa pump has two ends, wet and dry. The wet end is the volute with the impeller and the pump seal inside it; the intake, the discharge and a drain plug are on the volute. The dry end is the motor. Unlike a pool pump, it has no strainer pot, and it sits inside the cabinet.
One maker's word is often another's: topside control for control panel, spa pack for control box, air venturi for air control, headrest for pillow.
Not every tub has a circulation pump or an ozonator. On tubs without the small pump, the jet pump does the filtering too.
Questions and answers
What is the wet end of a hot tub pump?
The half that water runs through: the volute, the impeller inside it and the pump seal behind the impeller. The motor is the dry end. On many pumps the wet end can be turned in quarter steps to point the discharge at the pipe.
Where is the pump on a hot tub?
Inside the cabinet, in the equipment bay behind a panel that comes off. One manual puts the bay below the control panel. The heater and the control box sit beside the pump, with a circulation pump and an ozonator on tubs that have them.
What does the diverter valve on a hot tub do?
It is a knob or lever on the rim. Turning it sends the jet pump's water to a different combination of jets. It is not the air control, which only adds air to the jets.
What is the difference between a jet pump and a circulation pump?
The jet pump is the large one that drives water to the jets. A circulation pump is a small, quiet pump that runs constantly to filter the water. Some tubs have no circulation pump: the main pump runs at low speed to filter instead.