Spa Pressure Switches

Spa Pressure Switches

60 products

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    Air Vacuum Switch, Pentair GRN-0.65

    Air Vacuum Switch, Pentair GRN-0.65

    Air Vacuum Switch, Pentair GRN-0.65

    Pentair Pool Products

    472180
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    $53.50
    $111.60 $53.50
    Liquid error (snippets/card-product line 647): comparison of String with 0 failed
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    Vacuum Switch, Cal Spa V4001P-DX Repl, 21A, 1/8"mpt, Generic

    Vacuum Switch, Cal Spa V4001P-DX Repl, 21A, 1/8"mpt, Generic

    Vacuum Switch, Cal Spa V4001P-DX Repl, 21A, 1/8"mpt, Generic

    Tecmark Corporation

    V4003P-DX
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    $46.90
    $101.30 $46.90
    Liquid error (snippets/card-product line 647): comparison of String with 0 failed
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    Pressure Switch, Len Gordon, 25A, 1/8"mpt, SPDT, Stainless

    Pressure Switch, Len Gordon, 25A, 1/8"mpt, SPDT, Stainless

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    Pressure Switch, Len Gordon, 25A, 1/8"mpt, SPDT, Stainless

    Len Gordon

    800122-3
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    $40.80
    $87.30 $40.80
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  • -54% Off
    Pressure Switch, Len Gordon, 25A, 1/8"mpt, SPDT, Plastic

    Pressure Switch, Len Gordon, 25A, 1/8"mpt, SPDT, Plastic

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    Pressure Switch, Len Gordon, 25A, 1/8"mpt, SPDT, Plastic

    Len Gordon

    800120-3
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    $34.40
    $75.60 $34.40
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  • -53% Off
    Pressure Switch, Len Gordon, 1A, 1/8"mpt, SPDT, 15-30psi

    Pressure Switch, Len Gordon, 1A, 1/8"mpt, SPDT, 15-30psi

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    Pressure Switch, Len Gordon, 1A, 1/8"mpt, SPDT, 15-30psi

    Allied Innovations

    800134-3
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    $28.20
    $60.80 $28.20
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  • -52% Off
    Pressure Switch, PresAirTrol Side Spout, 21A, 1/8"b, DPDT

    Pressure Switch, PresAirTrol Side Spout, 21A, 1/8"b, DPDT

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    Pressure Switch, PresAirTrol Side Spout, 21A, 1/8"b, DPDT

    Pres Air Trol

    PR21120A
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    $36.20
    $76.90 $36.20
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  • -53% Off
    Pressure Switch, Herga, 21Amp, 1-5psi, 1/8"mpt, DPDT

    Pressure Switch, Herga, 21Amp, 1-5psi, 1/8"mpt, DPDT

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    Pressure Switch, Herga, 21Amp, 1-5psi, 1/8"mpt, DPDT

    Herga Electric

    6742-20-U226
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    $41.30
    $88.50 $41.30
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  • -53% Off
    Pressure Switch 3046, 25A, Tecmark, 1/8"b, SPNO, Z Bracket

    Pressure Switch 3046, 25A, Tecmark, 1/8"b, SPNO, Z Bracket

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    Pressure Switch 3046, 25A, Tecmark, 1/8"b, SPNO, Z Bracket

    Tecmark Corporation

    3046
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    $40.50
    $86.60 $40.50
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  • -47% Off
    Pressure Switch, Lochinvar EnergyRite Heater, Water

    Pressure Switch, Lochinvar EnergyRite Heater, Water

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    Pressure Switch, Lochinvar EnergyRite Heater, Water

    Lochinvar

    PRS3406
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    $73.20
    $139.30 $73.20
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  • -54% Off
    Pres Air Switch

    Pres Air Switch

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    Pres Air Switch

    TODELETE

    TRP111E-12PR
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    $31.30
    $68.30 $31.30
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  • -51% Off
    Air Vacuum Switch, Pentair PRL-1.35

    Air Vacuum Switch, Pentair PRL-1.35

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    Air Vacuum Switch, Pentair PRL-1.35

    Pentair Pool Products

    472183
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    $52.40
    $109.00 $52.40
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  • -51% Off
    Air Pressure Switch, Pentair YEL-0.95

    Air Pressure Switch, Pentair YEL-0.95

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    Air Pressure Switch, Pentair YEL-0.95

    Pentair Pool Products

    472182
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    $52.40
    $109.00 $52.40
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Spa Pressure Switches

Restore heater protection and safe operation to your spa with replacement spa pressure switches from Tecmark, PresAirTrol, Gecko Alliance, Hydro-Quip, and Jandy/Zodiac. PST Pool Supplies stocks a full range of spa heater pressure switches, vacuum switches, and pressure switch harnesses — starting from $14.20.

A spa pressure switch monitors water pressure in the heater manifold and signals the control board when adequate flow is present — similar in function to a flow switch but operating on pressure differential rather than direct flow detection. When the pressure switch fails, the spa typically displays a heater error or fails to heat even with the pump running. The key products in this collection: Tecmark pressure switches are the most widely stocked spa pressure switches — the Tecmark 3903-DF (1A, 1/8\" MPT, SPST, field-adjustable) allows the trip pressure to be set on-site to match the pump and plumbing configuration; the Tecmark 4015P (25A, 1/8\" MPT, SPDT, plastic) and Tecmark 3001 (25A, 1/4\" compression, SPNO) handle higher-current direct switching applications. The Tecmark 3029 (25A, SPNO) and 3032 (1A, 1/4\" compression, SPNO) cover additional circuit configurations. PresAirTrol switches — the Tinytrol series (21A, 1/8\" MPT, SPST and SPDT at 2 psi) provide compact, high-amperage switching for applications where the pressure switch directly controls pump or heater loads. The PresAirTrol adjustable vacuum switch (25A, 1/8\" MPT, adjustable 135–300\" water column) serves suction-side detection applications. The Gecko 1A pressure switch (1/8\" MPT, SPNO, 2.0 psi, metal body) is the OEM specification for Gecko Alliance controlled spas. The Jandy/Zodiac LRZE pressure switch (1–10 psi) serves Jandy and Zodiac heater and equipment installations in in-ground spa and pool systems. The Hydro-Quip pressure switch harness (14\", 3-pin) provides the wiring harness that connects the pressure switch to the Hydro-Quip control board.

When diagnosing a pressure switch issue: a failed switch typically reads open circuit (no continuity) at full pump pressure when tested with a multimeter. An adjustable switch (Tecmark 3903-DF) can be recalibrated before replacement if the pump's pressure output has changed due to impeller wear or plumbing modifications. Always match the replacement switch's amperage rating, connection size (1/8\" MPT or 1/4\" compression), and switch configuration (SPNO, SPDT, or SPST) to the original.

Shop spa pressure switches at PST Pool Supplies and restore your heater's water-flow safety protection with the correctly matched pressure switch.

Frequently Asked Questions

What is the difference between a spa pressure switch and a flow switch?
Both protect the heater from running without adequate water flow, but they detect flow differently: Flow switches use a mechanical paddle or magnetic sensor inside the water stream — when water flows past, it deflects the paddle or moves a magnetic float, closing the circuit. Flow switches directly detect water movement. Pressure switches detect the pressure differential created by the pump — when the pump runs and generates pressure in the heater manifold, the pressure switch closes (or opens, depending on SPNO/SPNC configuration). Pressure switches do not contact the water directly; they sense the pressure through a small port in the heater tube or manifold. Practical differences: pressure switches can false-trigger if the pump loses prime (no water but pump running builds no pressure), and can be affected by plumbing restriction changes. Flow switches more directly confirm water movement but have a mechanical paddle that can stick open or closed. Many modern spa control systems use one or the other — some use both in series for redundant protection. Diagnose by the component your spa specifies: if your heater has a threaded pressure port on the tube body, it uses a pressure switch; if the heater manifold has a separate T-fitting with a sensor, it uses a flow switch.
What do SPNO, SPDT, and SPST mean on pressure switch specifications?
These abbreviations describe the switch's electrical contact configuration: SPNO (Single Pole, Normally Open) — the switch contacts are open (circuit disconnected) at rest/low pressure, and close (circuit connected) when pressure reaches the trip point. This is the most common configuration for spa heater pressure switches — the circuit is open (heater off) with no pressure, and closes (heater can energize) when pump pressure is detected. SPNC (Single Pole, Normally Closed) — the opposite: contacts are closed at rest and open when pressure is applied. Less common in spa heaters. SPST (Single Pole, Single Throw) — has one set of contacts that either opens or closes at the trip pressure (the normally-open or normally-closed behavior is specified separately). The Tecmark Tinytrol comes in both SPST SPNO and SPST SPDT versions. SPDT (Single Pole, Double Throw) — has both normally-open and normally-closed contacts on the same switch, allowing the same switch to signal two different circuits simultaneously (one that closes on pressure, one that opens). SPDT switches are used when the control board needs a two-state signal or when both a high-pressure and no-pressure condition must be detected. Always match the switch configuration exactly — substituting SPDT for SPNO in a single-signal application works (use only the SPNO terminals), but substituting SPNO for SPDT in a dual-signal application will leave one circuit uncontrolled.
How do I replace a spa heater pressure switch?
Pressure switch replacement is a simple repair: (1) Turn off spa power at the breaker. (2) Locate the pressure switch — it threads into a small port on the heater tube body or manifold, typically a brass or stainless 1/8" NPT port, with one or two wires connected to its terminals. (3) Disconnect the wires from the switch terminals (photograph the wiring first). (4) Unscrew the pressure switch counterclockwise — use a wrench on the switch body hex, not the pressure port. Some switches use a 1/4" compression fitting rather than NPT thread — loosen the compression nut and pull the switch probe out of the port. (5) Apply PTFE thread tape (2 wraps) to the NPT threads of the new switch. (6) Thread the new switch in clockwise, hand-tight then 1–2 turns with a wrench — do not overtighten into brass or plastic ports. For compression-type switches, slide the ferrule and nut onto the probe, insert into the port, and tighten the compression nut. (7) Reconnect wires and restore power. The replacement switch must match the original's connection size (1/8" MPT or 1/4" compression), amperage rating, and SPNO/SPDT configuration.
Can I adjust a field-adjustable pressure switch, and when should I?
Yes — the Tecmark 3903-DF and similar field-adjustable pressure switches have a small adjustment screw that changes the trip pressure (the pressure at which the switch activates). Adjustment is appropriate when: (1) The spa displays a pressure error at lower pump speeds but heats normally at high speed — the switch trip pressure may be set higher than the pump generates at low speed. Lowering the trip pressure allows the heater to operate at reduced pump speeds. (2) The spa heats even with a partially clogged filter — the switch may be set too low, allowing the heater to run at pressures that indicate inadequate flow. Raising the trip pressure ensures the heater only operates at full flow. (3) A new pump generates different pressure than the original — pump replacement can change system pressure; the switch may need recalibration to match. Adjustment procedure: with the spa running at normal speed, use a small screwdriver on the adjustment screw (clockwise increases trip pressure, counterclockwise decreases it) while monitoring whether the heater activates. Make small 1/4-turn adjustments and allow the system to stabilize between adjustments. If the switch cannot be adjusted to a reliable trip point, replace it — a new switch at the correct pressure range is more reliable than a worn adjustable switch.