How do I know what size hot tub pump I need?

Match the old pump's voltage, number of speeds, amps, frame size, plumbing size, and discharge direction. Amps are a more reliable match than the horsepower printed on the label.

Can I put a bigger pump in my hot tub?

Not safely without checking. The plumbing, the jets, and the control board's relay and fuse are sized for the original pump's amp draw. A larger pump can overload the board and may not improve jet feel.

What is the difference between a 48 frame and 56 frame pump?

Frame is the motor's physical size. A 48-frame motor is about 5-5/8 inches in diameter. A 56-frame motor is about 6-1/2 inches. They use different wet ends and mounting patterns.

Is a 1-speed or 2-speed pump better?

Use whichever your tub was built with. A 2-speed pump runs low for filtering and heating and high for jets. A 1-speed pump is jets only, on tubs that have a separate circulation pump or another 2-speed pump.

Can I replace just the motor or just the wet end?

Yes. If the motor is sound and the wet end leaks or is cracked, replace the wet end. If the motor has failed and the wet end is good, replace the motor. They must match in frame and horsepower rating.

Which hot tub pump do I have? How to read the pump label

To identify your hot tub pump, read the label on the motor and write down six things: voltage (115 or 230), number of speeds (one or two), amps, horsepower, frame (48 or 56), and the brand and part number. Then measure the plumbing unions (1.5 inch or 2 inch) and note whether the outlet is on the side or the center. A replacement that matches those will fit and run correctly.

Step 1: Find the pump and its label

Turn off power at the breaker.
Open the equipment bay, usually the panel below the topside controls.
Find the pump or pumps. Each is a motor (the metal cylinder) bolted to a wet end (the plastic housing the pipes connect to).
Find the label on the motor body. It may face the back or bottom. Use your phone camera to reach it.
Take a clear photo of the whole label and another of the wet end, including any numbers molded into the plastic.

Step 2: Read the motor label

Label field	Example	What it means
HP	2.0, or 4.0 SPL	Horsepower. Often inflated on spa pumps. Use as a rough guide only.
VOLTS	115 or 230	Must match. A 230V pump on 115V will not run. The reverse destroys it.
AMPS	10.0/3.0	Current draw. Two numbers means two speeds: high/low. The best single number to match.
RPM	3450/1725	Two numbers means a 2-speed motor. 3450 alone means 1-speed.
FR	48Y or 56Y	Frame size. Determines which wet end fits.
HZ	60	60 Hz for North America.
SF	1.0	Service factor. Part of the true horsepower picture.
Model or part number	Maker's code	The fastest route to an exact match, if still readable.

Why amps matter more than horsepower

Spa pump horsepower is marketing-prone. One maker's "5 HP" may be another's "3 HP." Labels may show brake horsepower, or "SPL" (special) ratings that are not comparable. Amps are what the motor actually draws, and what your control board's relay and fuse were sized for. Choose a replacement within about 10% of the original amps on high speed, and never higher than the board is rated for.

Step 3: 48 frame or 56 frame?

	48 frame	56 frame
Label marking	48, 48Y	56, 56Y
Motor diameter	About 5-5/8 inches	About 6-1/2 inches
Typical use	Smaller and mid-size pumps	Higher output pumps, larger tubs
Wet end	48-frame wet ends only	56-frame wet ends only

If the label is unreadable, measure across the round motor body. The two sizes are different enough to tell apart with a tape measure. A 56-frame pump is also heavier and longer, so check that a replacement of the same frame is used or that there is room.

Step 4: Speeds

2-speed: low speed for filtration and heating, high speed for jets. Common as "pump 1" on tubs without a circulation pump. The cord has four wires.
1-speed: jets only. Common as "pump 2," or as pump 1 on tubs with a circulation pump. The cord has three wires.

Replace like with like. The control board is configured for one or the other.

Step 5: Measure the plumbing

Pump size is described by the pipe size, not the size of the union you can see.

Plumbing size	Outside diameter of the wet end's threads
1.5 inch	About 2-3/8 inches
2 inch	About 3 inches

Measure both the suction (front, center) and the discharge (top or side). Some pumps have 2 inch on both, some have mixed sizes.

Step 6: Discharge orientation

Side discharge: the outlet comes off the top of the wet end, offset to one side. Most can be rotated to several positions.
Center discharge: the outlet points straight up from the centerline.

Note which you have and which direction it points. A photo from the front settles it.

Circulation pumps are different

A circulation ("circ") pump is a small, quiet pump that runs most or all of the day to filter and heat. It looks nothing like a jet pump: it is often the size of a large coffee mug with 3/4 inch or 1 inch hose barbs, or a compact low-amp pump with 1.5 inch unions. For these, match:

Brand and model number on the label
Voltage (115 or 230)
Connection type and size: hose barb or threaded union
Flow rating, if shown

A failed circ pump usually shows up as a flow error and a tub that will not heat, with a clean filter. See hot tub not heating.

Your pump ID checklist

Brand and part number
Volts: 115 or 230
Speeds: 1 or 2
Amps: high and low
HP as labeled
Frame: 48 or 56
Suction and discharge size: 1.5 or 2 inch
Discharge: side or center
Cord: plug type at the control box, if it has one

With that list you can match a complete pump, a motor, or a wet end in hot tub pumps.

Whole pump, motor only, or wet end only?

Wet end only: cracked housing, worn impeller, or leaking seal on a healthy, quiet motor. See hot tub leaking.
Motor only: seized or screeching motor with a good wet end.
Complete pump: older pump, or you want the simplest swap. It arrives assembled with a new seal.

Symptoms and repair-or-replace advice are in hot tub pump humming or not working.

A note on installation

The plumbing connections are hand-tightened unions. The power connection is at the control box or inside the motor's wiring compartment and must match voltage and speed wiring exactly. If you are not experienced with that, have a technician connect it. You can get bids from local pros.

General guidance. Follow your manufacturer's instructions and chemical labels. Electrical work should be done by a licensed professional.