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Grasslin 24HR Time Clock FM-1STU-L - Bubbles Supply

Grasslin 24HR Time Clock FM-1STU-L

Part #: FM-1STU-L

$145.85
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About this time clock

The Grasslin FM-1STU-L is a 24-hour mechanical time clock designed for spa and hot tub electrical control systems. This 24VAC, 20-amp SPDT (single pole, double throw) timer provides reliable automated control for spa pumps, heaters, and lighting circuits. Built to Intermatic's exacting standards, this replacement time clock delivers the precise timing control your spa system needs for optimal operation and energy efficiency.

At Bubbles Supply, we guarantee this Grasslin time clock is the exact fit for your spa's control panel, backed by our comprehensive 1-year warranty. Every order ships the same day to minimize your spa downtime. This mechanical timer features a simple dial interface for easy programming of daily on/off cycles. Always verify your existing time clock's voltage and amperage ratings before installation, and ensure power is disconnected at the breaker before beginning any electrical work.

Exact part number

FM-1STU-L

Save this for ordering or warranty claims

Also known as / Replaces

This part replaces or is interchangeable with:

  • 24-hour mechanical spa timer
  • FM 1STU L
  • Grasslin FM1STUL
  • Intermatic FM-1STU-L

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

Technical specifications

Voltage
24VAC
Amperage
20A

Common symptoms this part fixes

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

  • Spa pump or heater runs continuously with no shutoff
  • Spa equipment never turns on automatically
  • Timer dial not advancing or stuck
  • Spa not following programmed on/off schedule
  • Timer tripped circuit or failed to cycle at correct time

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

Before you buy — quick checklist

  • Confirm your existing timer is rated 24VAC — this is a low-voltage control timer, not a line-voltage timer
  • Verify your control board or panel uses an SPDT (single pole, double throw) switching configuration
  • Match the trippers/program pins if your existing timer uses daily scheduling tabs
  • Check the physical mounting footprint and terminal layout against your existing timer before ordering
  • Confirm 20A is sufficient for your circuit load — do not upsize amperage to compensate for a failing circuit

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

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

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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