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

Last updated: September 2026

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

What is an air button?

An air button, sometimes called a pneumatic button or air switch, is a push button found on many hot tubs, swimming pools, hydro massage baths and swim spas. It lets you switch a pump or air blower on or off from inside the tub or pool.

Why not use a normal switch? Safety. You’re in or around water, and water and mains electricity don’t mix. An air button solves that because no electricity is involved at the button. You press it and it sends a puff of air down a small tube. It’s a brilliantly simple idea and works well, right up until it doesn’t. See also my guide to hot tub air switches.

What is a latching relay?

The latching relay is the other half of the system. It lives in the equipment pit or control box, away from the water, and it does the actual electrical switching.

What makes it different from an ordinary relay is how it behaves. The first puff of air switches it on and it stays on. Press the button again and it switches off and stays off. It latches, hence the name. That gives you an on/off toggle from a single button.

How do they work together?

You press the air button in the tub. That squeezes a little air and sends a pulse down a thin tube, usually a few millimetres across, to the equipment area. At the other end the pulse triggers the latching relay, which switches the pump or blower on, or off if it was running.

No wiring near the water and no risk to the bather. Just a puff of air doing the work.

How to know when they need replacing

These parts do fail over time. The most common causes are:

• Water in the airline: the air pulse loses its effect and the relay stops responding reliably.
• Water in the latching relay: not what you want in a relay handling mains voltage.
• A stuck or unresponsive button: the button can seize, particularly on older installations.

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

If your blower is what’s misbehaving, also read water in a hot tub air blower and how to repair a hot tub blower.

How to change an air button and latching relay

This is one of the easier jobs on a hot tub or pool.

What you’ll need

• Replacement air buttons (matching the cut-out size of the old ones)
• Replacement latching relays
• New air tubing (it’s cheap, so always replace it at the same time)

Step 1: Turn off the power

Isolate the power at the breaker before you go near the control box. Don’t skip this.

Step 2: Remove the old air buttons

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

Step 3: Feed the new tubing through

Run the new tubing along the same route as the old, all the way from the button to the equipment pit or control box. Leave some slack at both ends.

Step 4: Fit the new air buttons

Fit the new buttons into the existing holes and connect the tubing to the back. Most air buttons have a push-fit or barbed connector, so push the tube on firmly.

Step 5: Change the latching relay

In the control box, unscrew the old relay and disconnect the wires. Take a photo first if you’re not confident, because the wires must go back exactly where they came from. Fit the new relay, reconnect the wires and connect the new airline to the relay’s air input.

Step 6: Test it

Restore the power and press the button. You should hear the pump or blower start straight away. Press it again and it should stop. Job done.

Common mistakes

• Replacing the button but keeping the old, wet tubing.
• Kinking or crushing the tubing when refitting.
• Buying a button that doesn’t fit the existing cut-out.
• Reconnecting the relay wires in the wrong places. Take a photo first.

Wrapping up

Air buttons and latching relays tend to be ignored until they stop working. When they fail, they’re cheap to replace and the job is well within reach of a capable DIYer. For how the pack side ties in, see the spa pack guide, and for the blower itself see the hot tub air blower guide and how to wire a hot tub blower.

If you need replacement air buttons, latching relays or airline tubing, I stock both my stores. For the USA head to parts4tubs.com, and for the UK it’s parts4tubs.co.uk. If you can’t find what you need, get in touch and I’ll do my best to help.

FAQs

How does a hot tub air button work?

You press the button, which sends a puff of air down a thin tube to a latching relay in the equipment area. The relay switches the pump or blower. No electricity is involved at the button.

Why has my air button stopped working?

Water in the airline or relay is the most common cause, or the button has seized. Replace the button, tubing and relay together.

What is a latching relay?

A relay that switches on with the first air pulse and stays on until the next pulse switches it off, giving a single-button on/off toggle.

Can I replace an air button myself?

Yes. Isolate the power, swap the button and tubing, then change the relay, taking a photo of the wiring first.

Are air buttons safe to use in a pool or tub?

Yes, that is the point of them. There is no electricity at the button, only air.

Got a question about your own setup? Drop it in the comments below. I read them all.

Cheers,
Andi

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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