How Does a Hot Tub Actually Work?

Once you know how a hot tub works, you can successfully operate and enjoy your tub for many years to come. In this article, we will highlight what you need to know about the workings of your hot tub, empowering you to learn about specific features that are best for you, how to maintain it, and how to troubleshoot any issues effectively and efficiently. (For common customer concerns and related questions about hot tub ownership, check out our convenient online Hot Tub Buyer’s Guide or simply download our “Ultimate Hot Tub Buyer’s Guide.” It’s a complete printable reference guide with in-depth insights into everything you need to know about buying and owning a hot tub!)
Let’s get started!

What Is a Hot Tub?

Simply put, the term “hot tub” is normally used to refer to an above-ground spa. A hot tub or spa is a completely self-contained vessel, and the hot water and jets provide a pleasurable soaking experience for users. While there are so many different makes and models of hot tubs, and some differences do exist (i.e. the filter placement), essential operations of all hot tubs are pretty much the same. It is this same mechanical construction that allows water containment and basic hot tub operations such as heating. So, now let’s take a quick look at the main hot tub components.

hot tub shell

What Are the Main Components of a Hot Tub?

The Shell:

It’s exactly what it sounds like! As the inner hot tub surface (typically made of acrylic or another weather and chemical resistant thermoplastic), this contains the water, has various seats in its mold, and provides mounting points for the jets. How can it withhold the weight of this water, equipment, and bathers? The shell is reinforced or supported with fiberglass backing, or high-density polyurethane foam or some combination of the two.


The purpose of the hot tub cabinet is two-fold. Not only does it provide structural support for the shell and equipment, but it also hides the less-aesthetically pleasing equipment like plumbing, pumps, and heaters behind stylish doors. Instead of wood cabinets on older models, today’s cabinets are made from weather resistant polymer and are extremely easy to maintain.


One or more pumps are needed to circulate the water in and out of the hot tub, filtering and operating the jets. The pump allows for two speeds: low speed for filtering (and most heating) and high speed for operating the jets. Low speed operation is controlled by the spa pack based on the thermostat and time clock, if one is present. High-speed operation, controlled by a spa pack air button, allows for high-pressure steams in the jets. And if you are curious just how many hours should you run your hot tub for adequate filtering, experts say that 24 hours/day with an energy-efficient pump is best, but between 2-4 hours twice a day is a minimum standard.

Jets or Hydro Jets:

Just about everyone’s favorite hot tub features are the jets. They are responsible for the powerful bubbles that massage the body and help relieve muscle soreness. In more technical terms, a jet is a nozzle, and the air that is drawn through a constricted section of it creates a pressurized venturi effect. The water stream generated through the pump mixes with the air and together (with a little help from the venturi effect), they create soothing and massaging bubbles that can be adjusted by the user.

hot tub jets


Some older hot tubs may use special air blowers to create additional bubbles in the water. These can be used instead of or in addition to the typical air jets, although their use dramatically increases electrical consumption, and hence cost of ownership.

Spa Pack: Controller and Heater:

The spa pack contains a controller and heater in one unit. The controller safely allows the filter, pump, heater, and jets to efficiently provide the functions of filtering, heating and water jets. The heater heats the water each time it circulates through the heater for a certain amount each time. The spa pack can also control the lights or provide power for an ozonator (water cleaning mechanism.)

Topside (or Spaside) Control:

The control pad allows bathers to change water temperature from inside or outside the hot tub. If people are using the tub for a longer amount of time, set the temperature to 98 or 99 degrees, and never let it exceed 104 degrees Fahrenheit! This control also lets the user control the pumps, lights, or blowers.

hot tub controls

Filters / Sanitation System:

Filters and water care sanitizers are critical to keeping your hot tub clean and your water clear. For optimal results, you need to know and follow your ideal maintenance instructions and schedule to keep your tub running the way it was designed to. The filters are usually located in a designated filter area accessible from the top of the hot tub itself and consist of one or more screw in filters with a strainer or skimmer.


While its functions are similar to chlorine or bromine systems, the ozonator also helps destroy organic material, but with a special light injected into the spa through a venturi. While effective for helping keep the hot tub clean, chemicals still must be added to the water for proper sanitization. The ozonator is typically controlled by the spa pack and is generally turned on whenever the low speed pump is operating.

Hot Tub Lighting:

Today’s hot tubs have so many beautiful lighting options, with controls conveniently located on the air button on the top surface of the tub. Whether it’s incandescent lights or energy saving LED lights in a variety of stunning colors with preset programs, you’re sure to find lighting that delivers the ultimate relaxing environment.

hot tub lighting

Equipment Area and Access Door:

While this may differ slightly between various hot tub models, look at your user manual to get an idea of where your parts and plumbing live. For any maintenance issues that you cannot do on your own, it is best to call a professional for next steps.

What Are a Hot Tub’s Basic Functions?

Now that you know the main components of a hot tub, you already understand how a hot tub works and its basic functionality:

  • Drain and fill the tub
  • Filter the water
  • Heat the water
  • Light the tub
  • Provide ozone injection
  • Operate the blower
  • Power the jets

– If your jets are not working properly:

  1. Check the drain cover and make sure it’s not blocked
  2. Check and clean (or replace!) your filter
  3. Check for an air leak, possible with an o-ring out of place or loose/cracked valve
  4. Clogged jet: While these are uncommon, this could be a sign of a broken part trapped inside and blocking the water flow
  5. Low water level: Your water flow will be impacted if your spa skimmer is sucking in air; monitor and replenish your water!

hot tub seat

How Does a Hot Tub Run?

Electricity is needed to run your hot tub, and it’s important to know your specifications (i.e. nameplate voltage) required to operate your spa, and to get a professional electrician to help with the installation.
And, should you leave your hot tub running? It depends on the weather. If you live in a warm climate with occasional soaks, you can turn the temperature down between uses. If you are in a colder climate and need it a few times a week, you’ll save money by leaving it running. However, if you are heading out for the winter, and don’t expect to use it for several months, it’s critical you consider using professional dealer services to winterize your tub properly

How Do I Keep My Hot Tub Running Smoothly?

Once you have your hot tub, keeping it maintained is up to you. Luckily, here at Mainely Tubs we are happy to help you with all of your questions on what it means to be a hot tub owner, how to run and maintain it, and how to find the hot tub that works best for you. Read our comprehensive “Hot Tub Buyer’s Guide” for even more valuable hot tub info or give us a call, email us, or pop by our showrooms in Scarborough, Maine or Rye, New Hampshire. We’re always happy to help you learn more.

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