🚀 New launch promo — 10% off orders over $300. Use code LAUNCH10
Bubbles Supply
Not sure which part you need? Upload a photo and we'll find it. →
36" Mechanical Thermostat 275-3124-00 - Bubbles Supply

36" Mechanical Thermostat 275-3124-00

Part #: 275-3124-00

$39.41
In stock — ships today
Qty
🔒 Secure checkout↩️ 30-day returns✅ 1-year warranty
Add to B2B order list

Not sure this fits?

Send us a photo of your old part — we'll confirm the right replacement before you order.

Upload a Photo
1-year warrantySame-day ship before 3pm CTPerfect Fit Guarantee30-day returns

About this sensor

The Robertshaw 36" Mechanical Thermostat (275-3124-00) is an OEM replacement sensor designed for spa and hot tub temperature control systems. This mechanical thermostat features a 36-inch capillary tube with a 1/4-inch sensing bulb, providing reliable temperature monitoring and regulation for your spa's heating system.

Built to Robertshaw's exacting standards, this thermostat effectively addresses common spa issues including overheating (OH), freeze conditions (ICE), and heater high-limit faults (HH). At Bubbles Supply, we guarantee an exact fit for your spa with same-day shipping and back every thermostat with our comprehensive 1-year warranty. The 36-inch capillary length offers flexibility for proper bulb placement in your spa's plumbing system. Ensure your spa's existing thermostat matches these specifications before ordering, and consider having a qualified technician handle installation for optimal performance.

Exact part number

275-3124-00

Save this for ordering or warranty claims

Also known as / Replaces

This part replaces or is interchangeable with:

  • 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 won't heat or hold temperature
  • Spa overheating or triggering OH fault code
  • Freeze protection (ICE) fault displaying on control panel
  • Heater high-limit (HH) fault that resets but returns
  • Erratic or unstable water temperature readings
  • Spa heater cycling on and off at wrong temperatures

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 36 inches; a mismatch can prevent proper bulb placement
  • Confirm your existing thermostat uses a 1/4-inch sensing bulb diameter
  • Verify the thermostat's temperature range matches your spa's operating requirements before ordering
  • Check whether your spa uses a mechanical thermostat versus an electronic sensor — this is a mechanical unit and is not interchangeable with digital sensors
  • Note the routing path from the control box to the bulb well in your spa's plumbing to ensure 36 inches of capillary tube is sufficient

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 36" mechanical thermostat (275-3124-00)
  • 36-inch capillary tube with 1/4-inch sensing 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.

🔒 Secure checkout · SSL encrypted·🇺🇸🇨🇦 Serving the US and Canada·↩️ 30-day hassle-free returns·📦 Same-day fulfillment