Spa Flow Switches

Spa Flow Switches

48 products

  • Dimension One Flow Switch with 3P MTA-100, 6560-961

    Dimension One Flow Switch with 3P MTA-100, 6560-961

    Dimension One Flow Switch with 3P MTA-100, 6560-961

    Dimension One

    SKU: PST-6560-961
    MPN: 6560-961
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 0 Website Price Number: 0 All Metafields: {"mpn":"6560-961","warehouselocations":"Idaho Falls, ID","warranty":"12 Months"}
    $50.50
    $105.30 $50.50
  • Flow Switch, Harwil Q12DS Cal Spa

    Flow Switch, Harwil Q12DS Cal Spa

    Flow Switch, Harwil Q12DS Cal Spa

    Harwil Corporation

    SKU: PST-26-578-1020
    MPN: Q12DS/CAL SPA
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 8410.0 Website Price Number: 8410.0 All Metafields: {"bundle":"gid:\/\/shopify\/Metaobject\/110354628673","mpn":"Q12DS\/CAL SPA","saleprice":"0","warehouselocations":"Memphis, TN | Tucson, AZ","warranty":"12 Months","websiteprice":"84.1"}
    $82.00
    $156.70 $82.00
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  • Sundance Spas Flow Switch "T" Only (No Flow Switch Included), No Bypass Valve

    Sundance Spas Flow Switch "T" Only (No Flow Switch Included), No Bypass Valve

    Sundance Spas Flow Switch "T" Only (No Flow Switch Included), No Bypass Valve

    Sundance Spas

    SKU: PST-SS-T2
    MPN: SS-T2
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 0 Website Price Number: 0 All Metafields: {"mpn":"SS-T2","warehouselocations":"Idaho Falls, ID","warranty":"12 Months"}
    $14.70
    $32.10 $14.70
  • Sundance Spas Flow Switch "T" Only (No Flow Switch Included)

    Sundance Spas Flow Switch "T" Only (No Flow Switch Included)

    Sundance Spas Flow Switch "T" Only (No Flow Switch Included)

    Sundance Spas

    SKU: PST-SS-T
    MPN: SS-T
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 1470.0 Website Price Number: 1470.0 All Metafields: {"mpn":"SS-T","saleprice":"0","warehouselocations":"Idaho Falls, ID","warranty":"12 Months","websiteprice":"14.7"}
    $14.70
    $32.10 $14.70
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  • Sundance Spas - Flow Switch, 2560-040

    Sundance Spas - Flow Switch, 2560-040

    Sundance Spas - Flow Switch, 2560-040

    Sundance Spas

    SKU: PST-SD2560-040
    MPN: SD2560-040
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 5850.0 Website Price Number: 5850.0 All Metafields: {"mpn":"SD2560-040","saleprice":"0","warehouselocations":"Idaho Falls, ID","warranty":"12 Months","websiteprice":"58.5"}
    $54.50
    $99.70 $54.50
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  • Resilience Chlorine Generator Flow Switch, HWFS

    Resilience Chlorine Generator Flow Switch, HWFS

    Resilience Chlorine Generator Flow Switch, HWFS

    Harwil Corporation

    SKU: PST-HWFS
    MPN: HWFS
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 5280.0 Website Price Number: 5280.0 All Metafields: {"mpn":"HWFS","saleprice":"0","warehouselocations":"Idaho Falls, ID","warranty":"12 Months","websiteprice":"52.8"}
    $42.70
    $108.10 $42.70
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  • LA SPAS Flow Switch, EL-62048

    LA SPAS Flow Switch, EL-62048

    LA SPAS Flow Switch, EL-62048

    LA Spas

    SKU: PST-EL-62048
    MPN: EL-62048
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 5740.0 Website Price Number: 5740.0 All Metafields: {"mpn":"EL-62048","saleprice":"0","warehouselocations":"Idaho Falls, ID","warranty":"12 Months","websiteprice":"57.4"}
    $53.50
    $111.80 $53.50
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  • Sundance Spas Flow Switch, 6560-860

    Sundance Spas Flow Switch, 6560-860

    Sundance Spas Flow Switch, 6560-860

    Sundance Spas

    SKU: PST-6560-860
    MPN: 6560-860
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 0 Website Price Number: 0 All Metafields: {"mpn":"6560-860","warehouselocations":"Idaho Falls, ID | Las Vegas, NV","warranty":"12 Months"}
    $70.10
    $128.70 $70.10
  • Sundance Spas Heater Flow Switch, 6560-857

    Sundance Spas Heater Flow Switch, 6560-857

    Sundance Spas Heater Flow Switch, 6560-857

    Sundance Spas

    SKU: PST-6560-857
    MPN: 6560-857
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 6040.0 Website Price Number: 6040.0 All Metafields: {"mpn":"6560-857","saleprice":"0","warehouselocations":"Idaho Falls, ID | Las Vegas, NV","warranty":"12 Months","websiteprice":"60.4"}
    $87.70
    $161.30 $87.70
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  • Sundance Spas, Heater Flow Switch, 6560-852

    Sundance Spas, Heater Flow Switch, 6560-852

    Sundance Spas, Heater Flow Switch, 6560-852

    Sundance Spas

    SKU: PST-6560-852
    MPN: 6560-852
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 5810.0 Website Price Number: 5810.0 All Metafields: {"mpn":"6560-852","saleprice":"0","warehouselocations":"Idaho Falls, ID","warranty":"12 Months","websiteprice":"58.1"}
    $53.80
    $97.90 $53.80
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  • Jacuzzi Spas, J400 Series Flow Switch, 6560-646

    Jacuzzi Spas, J400 Series Flow Switch, 6560-646

    Jacuzzi Spas, J400 Series Flow Switch, 6560-646

    Jacuzzi

    SKU: PST-6560-646
    MPN: 6560-646
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 0 Website Price Number: 0 All Metafields: {"mpn":"6560-646","warehouselocations":"Idaho Falls, ID | Las Vegas, NV","warranty":"12 Months"}
    $97.00
    $185.50 $97.00
  • Flow Switch Tee, Hayward Aqua-Rite/Logic

    Flow Switch Tee, Hayward Aqua-Rite/Logic

    Flow Switch Tee, Hayward Aqua-Rite/Logic

    Hayward Pool Products

    SKU: PST-43-150-1018
    MPN: GLX-FLO-T
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 4120.0 Website Price Number: 4120.0 All Metafields: {"mpn":"GLX-FLO-T","saleprice":"0","warehouselocations":"Bloomfield, CT | Murray, UT","warranty":"12 Months","websiteprice":"41.2"}
    $42.60
    $91.90 $42.60
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  • Sundance Spas - Gatsby Flow Switch, 353119

    Sundance Spas - Gatsby Flow Switch, 353119

    Sundance Spas - Gatsby Flow Switch, 353119

    Sundance Spas

    SKU: PST-353119
    MPN: 353119
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 3860.0 Website Price Number: 3860.0 All Metafields: {"mpn":"353119","saleprice":"0","warehouselocations":"Idaho Falls, ID","warranty":"12 Months","websiteprice":"38.6"}
    $52.10
    $108.80 $52.10
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  • Sundance Spas - Gatsby Flow Switch, 353111

    Sundance Spas - Gatsby Flow Switch, 353111

    Sundance Spas - Gatsby Flow Switch, 353111

    Sundance Spas

    SKU: PST-353111
    MPN: 353111
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 0 Website Price Number: 0 All Metafields: {"mpn":"353111","warehouselocations":"Idaho Falls, ID","warranty":"12 Months"}
    $38.60
    $86.00 $38.60
  • Cal Spas Heater Flow Switch, 2-Q-12DS50

    Cal Spas Heater Flow Switch, 2-Q-12DS50

    Cal Spas Heater Flow Switch, 2-Q-12DS50

    Cal Spas

    SKU: PST-2-Q-12DS50
    MPN: Q-12DS50/1/4S/NO/2/3.5FT
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 0 Website Price Number: 0 All Metafields: {"mpn":"Q-12DS50\/1\/4S\/NO\/2\/3.5FT","warehouselocations":"Idaho Falls, ID","warranty":"12 Months"}
    $59.80
    $124.60 $59.80
  • Flow Switch Kit, Harwil Q12DS, 1/2"mpt, 2A

    Flow Switch Kit, Harwil Q12DS, 1/2"mpt, 2A

    Flow Switch Kit, Harwil Q12DS, 1/2"mpt, 2A

    Horizon Spa & Pool Parts

    SKU: PST-26-578-1101
    MPN: Q12DS501.54SNO1K
    Sale Price Value: 0 Sale Price Number: 0 Website Price Value: 7230.0 Website Price Number: 7230.0 All Metafields: {"bundle":"gid:\/\/shopify\/Metaobject\/110354792513","discontinued":false,"mpn":"Q12DS501.54SNO1K","saleprice":"0","warehouselocations":"Tucson, AZ","warranty":"12 Months","websiteprice":"72.3"}
    $72.30
    $138.00 $72.30
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Spa Flow Switches

Restore proper heater protection and circulation monitoring to your hot tub with replacement spa flow switches for Sundance, Jacuzzi, Dimension One, Hayward, LA Spas, and Harwil systems. PST Pool Supplies stocks OEM-matched flow switches and flow switch tees from $14.70.

A spa flow switch is a safety device in the heater circuit that detects whether water is moving through the heater before allowing it to energize. Without water flow, a spa heater can overheat within seconds and destroy the heating element — the flow switch prevents this by sending a signal to the control board only when adequate flow is confirmed. When the flow switch fails, the spa may display a flow error code (FLO, FL, or similar) and disable the heater even when the pump is running normally. The key products in this collection: Sundance Spas flow switches cover the range of Sundance spa models — the flow switch tee (T-body only, no bypass) is the lowest-cost repair when only the switch body is damaged; the complete flow switch assembly replaces the full sensor unit. Multiple Sundance part numbers are stocked including 6560-040, 6560-860, 6560-857, 6560-852, and the Gatsby-specific 353119, covering different Sundance generations. The Jacuzzi J400 Series Flow Switch (6560-646) is the OEM replacement for Jacuzzi J400-series spas — one of the most commonly serviced Jacuzzi platforms. The Dimension One Flow Switch (6560-961) serves Dimension One spa models. The Harwil Q12DS is a precision differential pressure flow switch used in Cal Spa and other systems where a Harwil sensor is specified. The Hayward Aqua-Rite/Logic Flow Switch Tee serves Hayward salt chlorine generator and heater installations in spas. The Resilience Chlorine Generator Flow Switch (HWFS) is the replacement flow sensor for Resilience salt systems.

Diagnosing a failed flow switch: if the spa displays a flow error code with the pump running at high speed, first check for a clogged filter (restricted flow can trigger the switch correctly — the problem is flow restriction, not the switch). If the filter is clean and flow error persists, test the switch with a multimeter (it should close the circuit when the pump runs) — an open circuit at full pump speed confirms switch failure. Most flow switches thread into a tee fitting in the heater manifold and replace in under 15 minutes with the spa power off.

Shop spa flow switch replacements at PST Pool Supplies and restore your heater's safety protection with the exact OEM-matched sensor for your spa brand.

Frequently Asked Questions

What does a FLO or FL error code mean on my spa control panel?
A FLO or FL error code means the spa's control system is not detecting adequate water flow through the heater circuit. The heater is disabled as a safety precaution to prevent dry-fire damage. The error can be caused by: (1) Clogged filter cartridge — the most common cause; a dirty filter restricts flow enough that the flow switch doesn't register adequate circulation. Clean or replace the filter first before diagnosing the switch itself. (2) Air lock — an air bubble trapped in the heater manifold after refilling blocks water flow. Prime the system by loosening the union fitting on the pump slightly to release trapped air. (3) Failed flow switch — the switch mechanism has failed in the open position and no longer closes the circuit even with full pump flow. (4) Pump running at low speed — many spa flow switches require high-speed pump operation to trigger; if your spa is set to run on low speed only, the switch may not activate. (5) Closed or partially closed valve — verify all suction and return valves are fully open.
How do I test a spa flow switch to confirm it has failed?
Testing a spa flow switch requires a digital multimeter set to continuity or resistance: (1) Disconnect spa power at the breaker. (2) Locate the flow switch — it threads into a tee fitting in the heater plumbing manifold, typically near the heater tube. Two wires connect to the switch terminals. (3) Disconnect the two wires from the flow switch terminals. (4) Set the multimeter to continuity and touch the probes to the two switch terminals. With the pump off (and no flow), the switch should be open (no continuity — this is normal). (5) Restore power and run the pump at high speed (with meter probes still on the switch terminals). A functioning switch will close (show continuity) within a few seconds of pump startup. If the switch remains open at full pump flow with a clean filter, the switch has failed and needs replacement. Note: some flow switches use a normally-closed (NC) circuit that opens to signal flow — check your spa's wiring diagram to confirm the switch logic before testing.
Are spa flow switches interchangeable between brands?
Spa flow switches are partially interchangeable — the thread size and sensor sensitivity must match your heater manifold and control system. Most residential spa flow switches use one of two thread sizes: 1/2" NPT or 3/4" NPT for the tee fitting body. Within the same thread size, many flow switches from different brands will physically fit the same tee. However, the electrical output and sensitivity must also match — some control boards require a specific contact rating or switch type (normally-open vs. normally-closed). Sundance, Jacuzzi, and Dimension One use OEM-specific part numbers because their control boards are designed to work with sensors of a specific trip point (the minimum flow rate required to activate the switch). Using a switch with a significantly different trip point can cause the heater to lock out at normal flow rates or, worse, fail to protect at inadequate flow. Always use the part number specified for your spa brand and model when available. The Harwil Q12DS is specified for Cal Spa systems because it meets the differential pressure specification those systems require.
How do I replace a spa flow switch?
Replacing a spa flow switch is a straightforward repair: (1) Turn off spa power at the breaker — never work on spa plumbing with power on. (2) Locate the flow switch tee in the heater manifold — a T-shaped fitting in the plumbing line before or after the heater with a small cylindrical sensor threaded into the branch port. (3) Disconnect the two wires from the switch terminals (note which wire goes to which terminal, or photograph before disconnecting). (4) Unscrew the flow switch counterclockwise from the tee — most use 1/2" or 3/4" NPT thread; use an adjustable wrench on the switch body flats (not the plastic housing). (5) Apply thread sealant tape (PTFE) to the new switch's threads — 2 wraps is sufficient. (6) Thread the new switch in clockwise, hand-tight then 1/4 to 1/2 turn with a wrench — do not overtighten into plastic tee fittings. (7) Reconnect the wires (polarity typically doesn't matter for dry-contact switches, but follow the original wiring if the board has a specified configuration). (8) Restore power and test — the FLO error should clear within 30–60 seconds of pump startup.