Hot tub circulation pumps

Hot tub water has to pass through the filter and the heater for hours every day. On a tub without a circulation pump, the jet pump does that job on its low speed. That is a big motor doing light work, which wastes power: California's Energy Commission found two-speed pumps are inefficient in standby for exactly that reason. A circulation pump is a small, quiet pump built to run for hours. A common one, the Laing E10, is rated at 65 watts and about 14 gallons a minute, for continuous duty. Master Spas puts the draw at about 0.45 amps, against 3 to 4 amps for a two-speed pump on low.

Usually. The Commission estimates a separate low-wattage circulation pump can save nearly 15% of a spa's energy and up to half of the pumping energy used for filtering. Some makers also route the pump's waste heat into the water; Caldera says most of its circulation pump's energy ends up as heat in the tub. In California's test results, tubs that list a circulation pump as standard drew a median 83% of the state's limit for their size, against 89% for tubs that list none. Those groups differ in brand and insulation too, so judge a tub by what it costs to keep hot, not by the pump alone.

Makers disagree. Hot Spring and Caldera run theirs around the clock; Jacuzzi describes the pump on its J-300, J4 and J5 as an 8-hour pump. Marquis uses none and filters on its main pump's low speed for about 2.5 hours a day. CDC's Legionella toolkit, written for public and commercial hot tubs, tells operators to keep water flowing across the filter 24 hours a day. Master Spas, which offers its pump as an option, says standard filtration without one keeps the water clean enough.

It is one more part that runs all day and will wear out. Leslie's puts the average life at about 7 to 9 years, shortened by continuous running, and notes a replacement must match the voltage, amperage and fittings exactly. A spa retailer lists the extra up-front cost and more plumbing connections that can leak. Ask what a replacement costs and whether it is a standard part. To see the running cost in dollars, read hot tub running cost.