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12" Mechanical Thermostat 275-3123-00 - Bubbles Supply

12" Mechanical Thermostat 275-3123-00

Part #: 275-3123-00

$79.06
In stock — ships today
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Also replaces

275-3123-00
1-year warrantySame-day ship before 3pm CTPerfect Fit Guarantee30-day returns

About this sensor

Replace your faulty spa thermostat with this genuine Robertshaw 12" mechanical thermostat (275-3123-00). This OEM-quality sensor fits most residential spas and hot tubs, featuring a 12-inch capillary tube with 1/4" bulb for precise temperature monitoring and control. The mechanical design provides reliable operation without electronic components that can fail in humid spa environments.

When your spa runs too hot, too cold, or cycles erratically, this thermostat typically resolves HH (high heat), ICE (freeze protection), and OH (overheat) error codes. Bubbles Supply guarantees exact fit compatibility and ships same-day from our Canadian warehouse. Every thermostat includes our 1-year warranty for complete peace of mind. Ensure your spa is completely powered off before installation and verify capillary tube length matches your existing setup.

Exact part number

275-3123-00

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Also known as / Replaces

This part replaces or is interchangeable with:

  • 275-3123-00
  • bulb thermostat
  • capillary thermostat
  • capillary tube thermostat
  • mechanical spa thermostat

Looking for an older part number? Check our supersession lookup tool

Common symptoms this part fixes

If your spa is showing any of these signs, this part is likely your fix:

  • Spa displays HH (high heat) error code
  • Spa displays OH (overheat) error code
  • Spa displays ICE or freeze protection error code
  • Water temperature runs consistently too hot or too cold
  • Spa heater cycles on and off erratically
  • Spa will not reach or hold set temperature

Not sure if this is your problem? Try our diagnostic centre or .

Before you buy — quick checklist

  • Measure your existing capillary tube length — this unit is 12 inches, confirm it reaches your sensor well
  • Verify bulb diameter on your current thermostat matches 1/4 inch
  • Check whether your spa uses a mechanical thermostat or an electronic sensor — this is a mechanical unit only
  • Note the Robertshaw part number on your existing thermostat before ordering to confirm direct replacement
  • Inspect the sensor well or thermowell for corrosion or damage before installing the new thermostat

Reading the checklist now prevents 90% of returns. Worth the 60 seconds.

Install difficulty: Medium — Some experience neededTypically 30-60 minutes

What's in the box

  • Robertshaw 12" mechanical thermostat (275-3123-00)
  • 12-inch capillary tube with 1/4" bulb

If your order is missing any items listed above, contact hello@bubblessupply.com within 48 hours of delivery.

Warranty

1 year manufacturer warranty against defects

Covers manufacturing defects. Does not cover improper installation, normal wear, or accidental damage.

Warranty claims: warranty@bubblessupply.com

Perfect Fit Guarantee

Ordered with our help and the part doesn't fit? Contact us before installation. We'll resolve it with an exchange, replacement recommendation, or return approval.

Learn about our Perfect Fit Guarantee →

Shipping

We ship across the US and Canada. US orders ship from our US warehouse to US customers; Canadian orders ship from our Canadian warehouse to Canadian customers — no cross-border shipping, no surprise duties. In-stock orders placed before 3pm CT ship same day. Standard shipping $9.95 flat rate. Free shipping on orders over $200. Express options available at checkout.

Returns

30-day hassle-free returns on unused parts in original packaging. Contact us before returning to receive your RMA number.

Frequently asked questions

Check the Compatibility section above to confirm fitment for your spa brand and model. If your model is not listed, use our fitment selector at /pages/find-my-part or ask our parts AI for a personalized recommendation.

In-stock orders placed before 3pm CT ship the same day. You will receive tracking information by email as soon as your order ships.

We accept returns within 30 days of delivery for unused items in original packaging. Email returns@bubblessupply.com with your order number to start a return. Installed electrical parts cannot be returned for safety reasons.

Yes, all new parts come with a 1-year warranty against manufacturing defects. Warranty does not cover damage from improper installation or normal wear and tear.

Customer reviews

AI Fitment Assistant

Tell us your spa model and we will confirm this part fits before you buy.

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