LX Hot Tub Pumps: Part Numbers, Mounting Styles & Replacement Mistakes

Posted by The Spa Guy

LX pumps are some of the most widely used spa pumps in America. You’ll find them inside dozens of major hot tub brands because they are dependable, standardized, and readily available.

But when it comes time to replace one, that “standardization” is exactly what causes confusion.

Let’s break it down the right way.

How LX Pump Part Numbers Actually Work

Most LX spa pumps begin with WUA.

Common series numbers include:

WUA100
WUA150
WUA200
WUA300
WUA350
WUA400
WUA500

The number represents the horsepower class — but that is only part of the identification.

The numbers and letters before and after that series are what truly matter.

Example: Breaking Down a Full Part Number

Take this common pump:

56WUA400II

Here’s what it means:

56 → 56 frame motor
WUA → LX pump series
400 → 4 HP class
II → Two-speed pump

If you see:

56WUA300I

That would be:

56 frame
3 HP class
Single-speed

Even one letter difference can change the electrical draw or speed configuration.

Why Brand Numbers Make This Confusing

Many spa manufacturers use LX pumps but assign their own internal part numbers.

This makes it look brand-specific — but it usually is not.

For example:

A proprietary Watkins number may actually be an LX 56WUA400II.

Other brands may list both their internal number and the LX number on the same label.

The pump is the same. The catalog number is different.

That’s where a lot of people overpay.

The Mounting Base Issue (Common with Jacuzzi, Sundance & D1)

Here is where most replacement mistakes happen.

This mounting style is commonly found in Jacuzzi®, Sundance®, and Dimension One® hot tubs.

Instead of a fixed molded base, these pumps often use:

• A removable base plate
• A large worm-drive clamp
• A rotating motor mount

That clamp-style system allows the pump to rotate into tighter equipment areas.

If you order a standard fixed-base LX pump and your original used a clamp-style mount, it may not bolt up properly without adjustments.

Before ordering, verify:

• Does it have a clamp around the motor?
• Or does it have a fixed molded base attached directly to the motor?

Mounting style matters.

Horsepower vs Amperage (The Truth)

Ignore the big horsepower sticker.

Horsepower labels are marketing.

Amperage tells the truth.

When replacing an LX pump, always match:

• Voltage
• Amperage
• Speed
• Frame size
• Mounting style

Never upgrade amperage thinking you’re getting more power.

How to Read Your Pump Label

Two-speed example:

10.0 / 3.5

10.0 amps = high speed
3.5 amps = low speed

Use the high-speed amperage for replacement.

Single-speed pumps will only list one amperage value.

Real-World Amperage to HP Reference (230V)

8 amps ≈ 1 HP
10 amps ≈ 2 HP
12 amps ≈ 3 HP
14 amps ≈ 4 HP
16 amps ≈ 5 HP

These are real working averages — not marketing numbers.

Match the amperage closest to your original pump.

Why Upsizing Can Burn Up Your Spa

Increasing amperage increases electrical load.

That can overload:

• Control boards
• Heater circuits
• Relays
• Wiring
• Breakers
• Pump plugs

Example:

Two 16-amp pumps = 32 amps
5.5 kW heater ≈ 21 amps
Total = 53 amps

Most spas are wired for 50 amps.

The math doesn’t lie.

If someone told you that you have a 6 or 7 HP pump, you almost certainly do not.

115V Plug-and-Play Warning

True 2 HP 115V pumps are extremely rare.

Installing a higher amperage pump in a plug-in spa can:

• Melt wiring
• Damage control boards
• Trip breakers constantly
• Burn up the motor

Never increase amperage in a 115V system.

Frame Size: 48 vs 56

Measure across the back of the motor:

48 Frame → approx. 5¾ inches
56 Frame → approx. 6½ inches

Frame size must match for proper alignment and installation.

Why Buy From HotTubPartsOfAmerica?

Most manufacturers do not make their own pumps — they buy them from companies like LX and relabel them.

We cross-reference proprietary part numbers and get you:

• The correct LX equivalent
• The correct amperage
• The correct frame
• The correct mounting configuration

Without the inflated brand markup.

Need Help?

Text clear photos of your pump label and mounting style.

We’ll confirm it before you order.

? Text: 772-800-5445
☎️ Call: 844-500-4645

HotTubPartsOfAmerica.com
The Spa Guy