Our verdict: Nice to have
Variable-speed hot tub pumps
Short answer
Almost no hot tub uses a variable-speed jet pump. Of the 531 jet pumps whose speed the makers state, 331 are two-speed and 200 single-speed; the only variable-speed pumps we found drive one massage seat, at Cal Spas and Master Spas.
Nice to have
Don't pay extra for the variable-speed label. In hot tubs it mostly drives one massage seat, as on Cal Spas' Throttle Seat and Master Spas' LSX 30, and one added later runs like an ordinary pump on a standard two-speed control board.
What is a variable-speed hot tub pump?
Most hot tub jet pumps have one or two fixed speeds. A two-speed pump runs slowly for filtering and heating and fast for the jets; a single-speed pump only runs fast, so the tub needs another way to filter: all 48 tubs in our data whose jet pumps are all single-speed list a small circulation pump as standard. A variable-speed pump has an electronically controlled motor that can run at many speeds in between. Jacuzzi says variable-speed pumps are typically quieter and make less heat and vibration, which reduces wear.
Does a variable-speed pump save energy?
It can, because a pump's power draw falls much faster than its speed. ENERGY STAR's pool pump guidance says halving a pump's speed cuts its energy use to one-eighth. That is why variable-speed pumps are common on swimming pools, which filter for many hours a day. California's Energy Commission lists variable-speed motors and controls as a further efficiency step for spas, but one that takes investment from the makers. In hot tubs the low-speed job is usually handed to a circulation pump instead, which does the slow job with a small motor of its own.
Which hot tubs have a variable-speed pump?
Very few, and not for filtering. Cal Spas sells an optional Throttle Seat that adds a variable-speed pump with its own control panel to one seat. Master Spas' LSX 30 runs its Xtreme Therapy Seat on a variable-speed pump so owners can set the massage strength. Both are about adjusting one massage, not lowering the power bill. Jacuzzi, Dimension One, Sundance and Nordic list every jet pump as one- or two-speed. The split follows each maker's design: most of Sundance's 780, 880 and 980 tubs use single-speed jet pumps with a separate circulation pump, while every Nordic main pump is two-speed and does the filtering itself.
Can you add a variable-speed pump to a hot tub later?
Not usefully on most tubs. Standard spa control boards only switch a pump on and off, or between high and low, so an aftermarket variable-speed pump wired to one of them runs like an ordinary pump. Don't pay extra for the label. If a tub claims an energy saving, look for it in the tested standby watts; see hot tub running cost.
What to ask the dealer
- Does the factory controller slow this pump down for filtering?
- What does a replacement variable-speed pump cost after the warranty?
The details
Which brands offer it, the research behind the verdict, and the sources.
Which brands offer it
15 brands
Two-speed jet pumps
331
Single-speed jet pumps
200
Brands with a variable-speed pump
2 of 15
| Cal Spas | Optional, one seat (CS Throttle Seat) |
|---|---|
| Master Spas | One model (LSX 30 therapy seat) |
| American Whirlpool | None published |
| Artesian Spas | None published |
| Bullfrog Spas | None published |
| Caldera Spas | None published |
| Dimension One Spas | None published |
| Hot Spring | None published |
| Jacuzzi | None published |
| Marquis | None published |
| Nordic Hot Tubs | None published |
| PDC Spas | None published |
| Sundance Spas | None published |
| Vita Spa | None published |
| Wellis | None published |
What the research says
5 findings
- Government The CEC report lists advanced multispeed and variable-speed motors and controls as a further efficiency option, but says it requires manufacturer investment beyond insulation improvements.
- Maker Jacuzzi says variable-speed pumps are typically quieter and produce less heat and vibration, reducing wear.
- Technician A spa-building guide notes that standard spa packs switch pumps only on/off or high/low, so adding an aftermarket variable-speed pump doesn't deliver its benefits unless the controller is designed for it.
- Maker Cal Spas' optional CS Throttle Seat adds a variable-speed pump with its own control panel.
- Maker Master Spas' LSX 30 runs its Xtreme Therapy Seat on a variable-speed pump.
Common questions
Are variable-speed pumps worth it in a hot tub?
Rarely. Hot tubs usually hand the slow filtering job to a small circulation pump, and the few variable-speed pumps sold in hot tubs drive a single massage seat. Judge energy use by tested standby watts.
Why does a slower pump use so much less power?
A pump's power draw falls much faster than its speed. ENERGY STAR says halving a pump's speed cuts its energy use to one-eighth.
Sources
6
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