By The Hot Tub Professor

When it comes to diverter valves, there is a lot of confusion — especially about sizing. Let’s clear it up.

First Things First: 1-Inch vs 2-Inch

When you hear “1-inch” or “2-inch” diverter, that does NOT refer to the size of the cap or handle.

It refers to the plumbing that glues into the valve body.

• 1-inch diverter → 1-inch plumbing glues into the valve

• 2-inch diverter → 2-inch plumbing glues into the valve

That’s it.

What You’ll Actually Measure

If you measure across the threads:

• A 1-inch diverter cap will measure about 1 5/8 inches across the threads

• A 2-inch diverter cap will measure about 2 3/4 inches across the threads

The outer cap width on a 2-inch version may range from:

• 3 1/4"

• 4"

• Up to 5" (like the newer six-spoke style)

But the thread width is what matters.

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What Does a Diverter Do?

A diverter valve redirects water flow inside your hot tub.

Typically:

• 1-inch diverters → Neck jets or waterfall controls

• 2-inch diverters →

  • Foot jet control

  • Cluster of jets

  • Middle position = both

You turn it one way for one zone, the other way for another zone, or center for both.

It literally “diverts” power.

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Major Brands (And Yes, They Interchange)

Most modern diverters originated with:

• HydroAir

• Waterway Plastics

• CMP

Waterway and CMP models were essentially copied from HydroAir’s original design, and most of these interchange — as long as the thread width matches.

Now here’s where it gets interesting:

Brands like:

• Cal Spas

• Dynasty Spas

They both use Waterway diverters — but the caps were styled specifically for each brand. So they may look different… but they interchange.

That means you can upgrade the look.

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Buttress vs Non-Buttress (2-Inch Only)

On 2-inch valves you may see:

• Buttress threads

• Non-buttress threads

General rule:
They usually interchange.

BUT…

If your cap says “Buttress” on the bottom, stick with buttress.
If it says nothing, order non-buttress.

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Common Failure Issues

Here’s what goes wrong over time:

✔ Threads crack
✔ Caps break
✔ O-rings dry out
✔ Valve body pulls downward as tub shell sags

That last one is big.

As tubs age, the shell can sag slightly. The plumbing underneath becomes stiff. The valve body gets pulled downward, and suddenly:

• Not enough thread is exposed

• The cap won’t tighten properly

• Or it pops off

In those cases you may need to:

• Open the cabinet

• Push the valve body back up

• Support it underneath

• Or replace the valve entirely

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Can You Upgrade the Look?

Absolutely.

The newer six-spoke style caps are popular upgrades. They’re slightly larger (5" on many 2-inch versions), so make sure you have clearance before ordering.

But as long as:

• Thread width matches

• It’s 1-inch or 2-inch correctly

• Buttress status matches (if applicable)

You can modernize your tub while replacing the part.

You do NOT have to go back with the original look.

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Jacuzzi Premium Note

Jacuzzi Premium diverters are different.

Their thread width is about 3 7/8 inches across, even though they function like a 2-inch valve. They don’t label them as 2-inch — they simply call them diverters.

Always measure before ordering.

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How We Make This Easy

At SpaShopper.com, you’ll find:

• 1-inch diverters

• 2-inch diverters

• Caps by color

• Caps by style

• Caps by hot tub brand

If you’re unsure?

Text us pictures.

That’s the easiest way.

Send a photo and say:

“I want to update this to something more modern.”

We’ll send links back.
We may ask for another angle.
But we’ll make sure you get it right the first time.

Because when you order the wrong part — it costs both of us.

And we don’t want that.

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I am the Hot Tub Professor.
This is the first of many Spa Shopper Blogs to come.

Check us out today:
SpaShopper.com

More coming soon.