Many consumers are considering buying a hot tub but have questions – particularly “how does a hot tub work“. From start to end, this article will walk you through a complete hot tub functions, including all parts and piping.
How Hot Tubs Work #
The Control System (Spa Pack) #
The control system (also known as the spa pack) is your hot tub’s brain.
Everything the hot tub does is controlled by it, from turning on the jets to determining how much heat is poured into the water to turning on any lights and music.
This system will wear out over time or with heavy use. On average, it can give you 7-8 years of life, but it’s not unheard of to get 10 years out of it.
However, this does not necessitate the replacement of your hot tub. You’ll only need to purchase a new control system to keep the hot tub operational.
Control from the top or from the side of the spa #
There are two types of hot tub control systems: topside and spa-side.
Topside control systems are seen on standalone hot tub shells. This is the most common tub, and the control panel is positioned on the tub’s top edge. While you’re in the tub, you’ll have access to controls at your fingertips, making it easy to make modifications to the atmosphere.
The spa-side control systems, which include the pump, filter, and heater, are placed away from the tub. These systems are typically found in custom hot tubs that are built from the ground up and integrated into a landscaped backyard with an existing pool. Many spa-side systems come with a remote control that may be used to control the tub’s many functions.
While wireless remotes are available, hardwiring is the most frequent method. Running a wire from the system to a position on the spa’s deck where the remote can be easily accessed while in the tub is required.
Because most high-end designs are surrounded by concrete, this line should be added when the tub is built.
Operational Components (Plumbing)
A hot tub’s plumbing is a closed-loop system that cycles your water indefinitely for as long as it’s operating.
This entire process prevents stagnation, distributes chemicals, allows the filter and heater to do their jobs, and ensures that the jets have a constant stream of water.
Wiring a Hot Tub #
A hot tub or backyard spa is a great way to relax and have fun, but the installation must adhere to specific electrical codes. For most full-sized spas or hot tubs, the National Electrical Code (NEC) requires:
- Hard-wiring the spa into a ground fault circuit interrupter (GFCI)-protected 220 to 240V, 50- or 60-amp dedicated circuit.
- Installing a manual disconnect device, often called a spa panel, between your home’s electrical breaker panel and the spa.

120V vs 240V #
Spas and hot tubs that run on 120V are known as “plug-and-play”.
A dedicated standard outlet is required – no other appliances, lights, or other electrical devices should be connected to this circuit at any time. A 20 AMP BREAKER is required for this circuit.These types of hot tubs and spas include a GFCI-protected plug that should be plugged into a standard dedicated outlet, as described above. The outlet should be within 5-10 feet of the hot tub.
240V Hot Tubs & Spas will require a 40, 50 or 60 amp 2-Pole GFCI protected breaker. The amperage depends on the model of the hot tub or spa. The GFCI breaker can by positioned either in your house at the main panel or in a separate breaker box. Circuits for 240V units must be dedicated as well. All wires entering the spa have to be in a flexible waterproof conduit.
Hot Tub Plumbing #
The pump, return lines, manifolds, PVC tubes, and jets or hydrojets are all part of the return side, which pushes the clean, heated water back out to your hot tub.

Suction Line #
The suction side includes the pump (on low speed for sucking), skimmers, and suction lines, which sucks the water out of the tub and into the filtration system.
The filtration system, which includes the pump (to keep things moving), filter, heater, and sometimes an ozonator, filters and eventually heats the water being pulled in.
Return Line #
The return line of a hot tub is a PVC pipe that transports water from the heater (or ozonator) to the tub via the manifolds.
It’s similar to a suction line, but reversed.
Manifold #
The manifolds are located at the end of the return line. These are utilized to divert the returning water to each of the return jets by splitting it up.
Manifolds are available in a number of sizes to fit tubs with a few or many jets.
PVC Pipes #
Flexible pipes are attached to the manifolds. The filtered water is delivered to the tub by these pipes, which run from the manifold to the jets.
They’re composed of flexible PVC so they can easily wrap around the tub’s peaks and dips. This also helps to save space and creates cleaner lines.

Let’s take a closer look at the plumbing system by tracking the flow of water from the hot tub (the suction side).

Hot Tub Components #
Pump #
The pump in your spa can be thought of as the beating heart of your filtration system.
It is in charge of drawing water into the tub, passing it through the filtration system, and returning it to the tub. Everything else fails without a properly functioning pump, just like a human heart.
The suction created by one side of the pump is what pulls water in from the hot tub. The other side of the pump creates pressure by moving in the opposite direction.
It can be compared to a pendulum. By default, if one side is sucking in the water, the other side will be pushing it along.
Filter #
The water is pumped through the pipes after the pump and put through a specific hot tub filter.
A cartridge filter is the most popular type of filter for hot tubs. This is a pleated, cylindrical filter composed of polyester or paper. Pollutants destroyed by chlorine or bromine adhere to the filter and are removed from the water as it goes through it.
This method can also be done with a sand filter or a DE (diatomaceous earth) filter, however these are less frequent. Sand filters employ spiky silica sand to trap impurities, whereas DE filters filter water using grids and DE powder.
Note that some tubs incorporate the cartridge filter into the skimmer, which is where the filtration process starts. This is done to assist in the removal of huge debris so that it does not enter the spa system and cause harm to any equipment.
Heater #
There are numerous systems for heating the hot tub.
Electric, gas, and solar heaters are available in a variety of styles.
Electric heaters contain elements that run the length of a stainless steel pipe inside the unit. As the water flows through, the temperature of the water rises.
Hot Tub Options #
Inground Hot Tubs #
Inground hot tubs often use gas heaters, which require a gas line. Running this line might be very expensive, but on the plus side, these heaters are highly fast and effective at heating the water.
Solar heaters can also be used with your hot tub for a more environmentally friendly option. These use solar energy to heat the pipes that carry the water. While this heater is a possibility, its dependency on sunlight makes it less than ideal for nighttime tub use.
Of course, hot tubs are designed to be hot, but a temperature that is too high might cause injury. As a result, they have a failsafe built in to prevent scalding.
The optimal temperature for keeping the tub is between 100°F and 102°F, according to the US Consumer Product Safety Commission. At 104°F, most tubs will shut off.
Hot Tubs With Ozonators #
Ozonators are being installed by certain spa owners to help keep the water clean. If you elect to utilize one, it will be situated in the equipment chain after the heater.
Ozonators produce ozone gas, which is then injected into the water. This method uses ozone to eliminate impurities from the tub while lowering the amount of sanitizing chemicals required.
You can choose between two types of ozonators: ultraviolet light (UV) and corona discharge (CD). Because of its extended longevity, great efficiency, and lower size, CD is the most extensively used ozonator.
Hydrojets vs. Jets #
The jets are any hot tub’s calling card. The water from the filtering system returns to the tub through these entrance ports.
The water pressure of the jets may be changed, and the water can be shot in slow or fast motion.
As a result, they can also be used as massagers, providing an extra layer of relaxation for your muscles.
Water in, air in, and an air mixture outflow are the three components of hot tub jets.

Conclusion on How How Tubs Work #
A pressured stream of water is pumped through the filtration system’s pipes, out the jet, and into the tub by the hot tub’s pump. A venturi, which is a small hole in the jet that water is directed through, also mixes air into the stream. This is known as the “Venturi effect.”
This happens because when water fills up the pipe, its speed increases while its pressure lowers. This reduces the amount of water coming in and forces it through the little hole.
Because the air outside the jet has a higher pressure than the water inside the pipe, it is driven into the stream and mixed with it. This creates a pressured mixture of air and water, which is then ejected out the jets, resulting in the bubbles.
Air blowers are occasionally used in hot tubs to create bubbles. They’re typically installed on tubs with a large return line. Because the pump is so far away from the tub, the longer this line is, the fewer bubbles you’ll get. In most circumstances, a blower will be overkill if the equipment is somewhat close to the spa itself.
That’s all there is to it. You now understand how a hot tub works.