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Spa Parts Made Simple

Pumps, heaters, control boards, and replacement parts — without the confusion.

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Not sure which part fits your spa?

We make it easy to find the right replacement part — without guessing.

  1. Find your spa model
  2. Match the part number
  3. Order with confidence
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SpaShopper makes it easy to find quality hot tub and spa replacement parts without the frustration. From spa pumps and heaters to control boards, jets, filters, and plumbing components, we stock parts that fit a wide range of popular spa brands. Whether you’re fixing a heating issue, replacing a worn pump, or upgrading aging components, SpaShopper helps you get your spa running again quickly and confidently.

Mechancal Hi Limits

Mechanical hi limits (also called mechanical high-limit thermostats or capillary hi-limits) are safety devices with a bulb probe on a flexible capillary tube that monitor heater outlet water temperature. If the temp exceeds safe limits (typically 118–150°F depending on model), the switch opens to cut power to the heater, preventing overheating, dry firing, or damage—common in older or specific spa heater systems for reliable mechanical protection without electronics.

This category includes replacement mechanical hi limits and compatible options, featuring bulb diameters (1/4", 5/16", 3/16"), capillary lengths (12"–36"), temperature set points (e.g., 150°F Watkins-style), SPST contacts (single pole, single throw, 25A–30A rating), screw terminals, and mounting clips. Popular models include Invensys/Robertshaw (275-3290-00, 275-3287-00, 275-3148-00), Watkins (30209, 30208 equivalents), HydroQuip (34-0012 series), and cross-fits for older Balboa, ACC/CTI, Brett Aqualine, or universal heaters. Many are manual reset (push button) or auto-reset.

Mechanical hi limits vary by bulb size, capillary length, trip temperature, reset type (manual/auto), contact rating, and heater/manifold compatibility—precise matching ensures the bulb fits the thermowell/groove, capillary routes properly, and the switch integrates with the heater circuit.

Common problems include nuisance tripping (frequent shutoffs from scale, low flow, or faulty calibration), no heat (stuck open contacts or broken capillary), overheating without shutdown (failed switch), leaks at bulb mount from poor sealing, or corrosion on terminals from humidity/chemistry. Replacing a mechanical hi limit is straightforward—often a direct swap with bulb insertion into the heater well—and restores safe overheat protection.

To select the right mechanical hi limit:
- Identify your spa brand/model, heater type (flow-thru, low-flow), voltage/amp rating, bulb diameter/capillary length, trip temp (if marked), reset type, and any part numbers (e.g., 275-3290-00, 30209).
- Note symptoms (tripping too soon, no reset, visible bulb/capillary damage), error codes, or heater markings.
- Avoid guessing—send us clear photos of your existing mechanical hi limit (showing bulb probe, capillary tube length, terminals, mounting, heater well location, and spa label with model/serial number) for expert verification.

**Text or send photos to: 772-800-5445**  
**Or call us at: 844-500-4645**  
We'll confirm compatibility before you order.

SpaShopper is not affiliated with any spa manufacturer. Brand names and part numbers are used for compatibility and identification purposes only.

Shop our mechanical hi limits today to ensure reliable overheat safety and keep your spa heater protected.

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