How to Change an Air Button and Latching Relay on a Hot Tub, Pool or Spa Bath

If you’ve got an air button that’s stopped working, or a latching relay that’s given up the ghost, the good news is that this is a really straightforward job to do yourself. In this article — and the accompanying video — I’m going to walk you through exactly what these components are, how they work, and how to swap them out.

Let’s get into it.

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What Is an Air Button?

An air button — sometimes called a pneumatic button or linear actuator — is a push button that you’ll find on a lot of hot tubs, swimming pools, hydro massage baths, and swim spas. Its job is to let you switch an electrical component on or off, usually a pump or an air blower, from inside the tub or pool.

Now, you might be thinking — why not just use a regular switch? The answer is safety. You’re in or around water, and water and mains electricity really don’t mix. An air button solves that problem completely because there’s absolutely no electricity involved at the button itself. You’re just pressing a button that sends a puff of air down a small tube. That’s it.

It’s a brilliantly simple idea, and it works really well — right up until it doesn’t.

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What Is a Latching Relay?

The latching relay is the other half of this system. It lives in your equipment pit or control box, away from the water, and it’s the bit that actually handles the electrical switching.

What makes a latching relay different from a regular relay is the way it behaves. When it receives that first puff of air from the button, it switches on and stays on. Press the button again, it switches off and stays off. It latches — hence the name.

This is what gives you that nice on/off toggle behaviour from a single button press.

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How Do They Work Together?

Put it all together and it’s a pretty elegant system.

You press the air button inside the tub. That compresses a small amount of air and sends a pulse down a thin tube — usually a few millimetres in diameter — that runs from the button through to the equipment area. At the other end, that pulse of air triggers the latching relay, which switches the pump or blower on (or off if it’s already running).

No wires running anywhere near the water. No risk to the bather. Just a tiny mechanical puff of air doing the heavy lifting.

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How to Know When They Need Replacing

Over time, these components do fail. The most common culprits are:

• Water in the airline — if water gets into the tube, the air pulse loses its effectiveness and the relay stops responding reliably
• Water in the latching relay itself — obviously not ideal when you’ve got a relay handling mains voltage
• The button getting stuck or becoming unresponsive — physically the button may seize up, particularly on older installations

In the video, I was helping out a friend of mine called Billy who’d recently moved into a house with an existing pool. The pool was around 10 years old and the air buttons had clearly had water in them — one was physically stuck. Classic signs that it’s time to replace the whole lot: buttons, airlines, and relays.

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How to Change an Air Button and Latching Relay

This is genuinely one of the easier jobs you can do on a hot tub or pool. Here’s how to approach it.

What you’ll need:

• Replacement air buttons (make sure they match the cutout size of your existing ones)
• Replacement latching relays
• New air tubing (it’s cheap — always replace the tube at the same time)

Step 1 — Turn off the power

Before you go anywhere near the control box, isolate the power at the breaker. Don’t skip this step.

Step 2 — Remove the old air buttons

The buttons are usually a push-fit or screw-fit into the shell of the tub or the pool surrounds. Remove them and pull the old airline tubing back through with them.

Step 3 — Feed the new tubing through

Feed your new air tubing through the same route as the old. Run it all the way from the button location through to the equipment pit or control box. Leave a bit of slack at both ends.

Step 4 — Fit the new air buttons

Fit your new buttons into the existing holes and connect the tubing to the back. Most air buttons have a simple push-fit or barbed connector — just push the tube firmly onto the fitting.

Step 5 — Change the latching relay

Inside the control box, unscrew the old relay and disconnect the wires. Take a photo first if you’re not confident — you’ll want to put the wires back exactly where they came from. Fit the new relay, reconnect the wires, and connect your new airline to the relay’s air input.

Step 6 — Test it

Restore power at the breaker and press the button. You should hear the pump or blower kick in immediately. Press it again and it should turn off. Job done.

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Wrapping Up

Air buttons and latching relays are one of those things that tend to get ignored until they stop working. The good news is that when they do fail, they’re cheap to replace and the job is well within reach for any capable DIYer.

If you’re looking for replacement air buttons, latching relays, or airline tubing for your hot tub or pool, I’ve got both of my stores stocked up. For the USA head to parts4tubs.com, and for the UK it’s parts4tubs.co.uk. If you can’t find what you need, just get in touch and I’ll do my best to help you out.

Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi

 

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.

Fast forward to 2025, I've helped over 1400+ DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi