Hot Tub Air Switches: The Ultimate Guide (How They Work, Faults and Replacement)

Last updated: September 2026

When it comes to hot tub air switches, there’s a lot to unpack: what they are, how they work, why they fail and what to look for when you buy a replacement. Whether you’re new to them or just need a refresher, this guide covers everything you need to know.

What is a hot tub air switch?

Air switches (also called air buttons or pneumatic switches) are common on built-in and in-ground hot tubs, like the ones you see at resorts and leisure centres, and on whirlpool spa baths and pools. You don’t see them so often on modern acrylic hot tubs, because those come with a digital keypad, the topside control, which runs everything through the spa pack.

The big advantage is safety. An air switch lets you control a pump, blower or light from inside the water without any electricity at the button. The button just pushes air. All the mains wiring stays in the equipment bay or control box, away from the water and away from wet hands.

How does a hot tub air switch work?

An air switch system has three parts: the button, the tubing and the switch.

1. The air button

This is the part you press. Inside is a bellows (a flexible air chamber). When you press it, it squeezes a small puff of air into the tubing. It’s the most visible part, and it comes in lots of finishes and sizes. Hard push buttons have a sealed internal bellows to stop water getting into the air tube.

2. The air tubing

This is the thin flexible tube that connects the button to the switch. When you press the button, the air travels along it to the switch. It’s usually 1/8in (about 3mm) internal diameter. Some switches accept 1/8in or 3/16in tubing, so check yours. Leave a little slack at each end, and avoid tight bends that could kink it.

3. The air switch

This is where the electrical switching happens. The switch has a diaphragm that flexes when the air arrives, and that moves a set of electrical contacts. The contacts switch power to the pump, blower or light, or to a contactor or control board that does it for them.

In simple terms: you press the button, air travels down the tube, the switch clicks, and the equipment turns on. It’s a clever way to control electrical equipment without any wiring near the water.

Types of air switch

Type	How it behaves	Typical use
Latching (alternating)	First press on, next press off. The switch holds its own position	Switching a pump, blower or light directly, or a contactor
Momentary	Contacts only close while the button is pressed	Sending a signal to an electronic control board, which does the switching
Multi-function (sequencing)	Steps through several states with each press	For example, two-speed pumps (off, low, high)

You’ll also see contact arrangements such as SPST or SPNO (single pole, one circuit on or off), SPDT (single pole, switches between two circuits) and DPDT (two poles). And you’ll see spout positions, with the air inlet in the centre or on the side. Replace like for like wherever you can. Hot Tub Outpost’s air switch range gives a feel for how many variations there are, with ratings from 3A up to 25A.

Check the amp rating. The switch’s contacts have to handle the current of whatever they’re switching. A typical spa air switch is rated around 20–25A. If you’re switching a big pump, or you’re not sure, the air switch should switch a contactor (a heavy-duty relay) instead, and the contactor switches the pump. That’s a job for your electrician to specify.

Common problems and how to test them

Like most mechanical parts, air switches wear over time. These are the usual culprits:

The tubing

The most common issue is a leak, split or kink in the tubing, or a joint that’s come loose. If the air can’t get to the switch, the switch won’t work. Water in the tubing is another classic, especially on older installations. Air switch maker PresAir says the most common fault they see is a kink or leak in the air line. If you’re replacing a button or switch, replace the tubing at the same time. It’s cheap, and old tubing goes hard and cracks.

The button

Buttons can crack, stick or seize, particularly after ten years or more, and then they can’t push enough air to trigger the switch. Replacing a button is usually simple and inexpensive. Measure the hole in the tub wall, because buttons come in different sizes (1¼in, 1⅜in and 1¾in mounting holes are all common), and in flush and raised styles.

The switch

The diaphragm inside the switch can split, or the contacts can burn out, especially if the switch has been handling more current than it was rated for.

How to test it

PresAir’s quick test is a good one:

1. Press the button and listen at the switch. If you hear a click, the button and tubing are doing their job, and the problem is in the switch’s contacts or further down the line.
2. No click? The problem is the button or the tubing. Check for kinks, splits, loose joints and water in the line.
3. A hissing sound at the switch means the diaphragm has blown, and the switch needs replacing.
4. Testing the contacts: with the power isolated, a multimeter across the switch’s contacts should alternate between continuity and no continuity as you press the button. Only do this if you’re competent with electrics.

Replacing an air switch

Safety first: turn the power off at the breaker and the isolator before you go near the switch, and make sure it can’t be switched back on. Take a photo of the wiring before you disconnect anything, so the wires go back exactly where they came from. If you’re not comfortable working on mains wiring, get a qualified electrician to swap the switch. In the UK, the supply should have 30mA RCD protection, and in the USA, GFCI protection. Hot tub wiring explained covers the supply side.

• Replace like for like. Note the part number, the type (latching, momentary or multi-function), the contact arrangement, the amp rating, the spout position and the tubing size. Exact models can be hard to find, so you’re often looking for an equivalent that matches on those points.
• The tubing. It’s a standard size, so you just need the right length. Match the bore of your existing tubing, which is usually 1/8in.
• Check what’s included. Don’t assume a kit has everything you need. Many listings include the switch but not the tubing or the button. Always check the product description and photos.
• Test it. Restore the power and try each button before you close everything up.

I’ve gone through a full swap, button, tubing and latching relay, step by step in How to change an air button and latching relay on a hot tub, pool or spa bath.

Building your own air switch setup

If you’re putting together an air switch system for a DIY tub or pool, you’ll usually need to buy the parts separately: buttons, tubing and switches. The right setup depends on what you’re controlling. A blower, a pool light, a counter-current swim jet and a two-speed pump all need different switches and ratings. Plan where the air switch box goes, keep the tubing runs short and tidy, and let your electrician specify the switch or contactor for each load.

On most DIY hot tubs, the pumps, blower and heater are run by a spa pack and topside instead, which handles heating, filtration and load management for you. See the spa pack survival guide and Which Balboa topside control do I need? Air switches are still handy for extras, like a blower or a pool light. There’s more on those in The hot tub air blower guide, Blower or venturi? and Can I control a swimming pool light with a hot tub spa pack?

You’ll find air buttons, switches and tubing at parts4tubs.com, where there are hundreds of models, and at parts4tubs.co.uk in the UK. The listings have detailed photos, so you can check exactly what’s included. If you’re planning the control room for a new build, The Ultimate Hot Tub Control Room Guide covers the layout.

FAQs

How does a hot tub air button work?

Pressing the button squeezes a bellows, which sends a puff of air down a thin tube to an air switch in the equipment bay. The air moves a diaphragm, which switches the electrical contacts. There’s no electricity at the button.

What size is hot tub air switch tubing?

Usually 1/8in (about 3mm) internal diameter. Some switches also accept 3/16in, so measure your existing tubing before you buy.

Why has my hot tub air button stopped working?

Most often it’s the tubing: a split, a kink, a loose joint or water in the line. Press the button and listen at the switch. No click points to the button or tubing. A hiss means the switch diaphragm has failed.

What’s the difference between a latching and a momentary air switch?

A latching switch turns on with one press and off with the next, and holds its position. A momentary switch only closes while the button is pressed, and is used with an electronic control that does the switching.

Can I replace a hot tub air switch myself?

Replacing buttons and tubing is an easy DIY job. The switch itself is connected to mains wiring, so isolate the power first, photograph the wiring, and get a qualified electrician if you’re not confident.

Got an air switch question? Drop it in the comments below. I read them all.

Cheers,
Andi

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Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

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