🚀 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. →
Heater Split Nut 0121108025 - Bubbles Supply

Heater Split Nut 0121108025

Part #: 0121108025

$18.72
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 union/fitting

This Magic Plastics heater split nut (part #0121108025) is a crucial union component designed for spa and hot tub heating systems requiring a 2-1/2" FBT connection with large flange configuration. This OEM replacement part ensures secure, leak-free connections between heater manifolds and plumbing lines, maintaining proper water flow and system pressure in your spa's heating circuit.

Built to Magic Plastics' exact specifications, this split nut delivers the precise fit your spa needs to restore optimal heating performance. At Bubbles Supply, we guarantee an exact fit for your application and back every part with our comprehensive 1-year warranty. Most orders ship same-day, getting your spa back to perfect operating condition fast. Always verify your existing heater union measurements and connection type before installation to ensure proper fitment.

Exact part number

0121108025

Save this for ordering or warranty claims

Also known as / Replaces

This part replaces or is interchangeable with:

  • 2-1/2 inch FBT split nut
  • heater union split nut
  • heater union tail piece nut
  • union nut

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

Technical specifications

Union size
2-1/2 inch FBT (Female Buttress Thread), large flange

Plumbing notes

  • Union size: 2-1/2 inch FBT (Female Buttress Thread), large flange

Need help measuring? Email hello@bubblessupply.com with a photo of your existing plumbing.

Common symptoms this part fixes

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

  • Weeping or dripping leak at heater union connection
  • Cracked or brittle split nut causing loss of seal
  • Split nut won't tighten or hold pressure
  • Heater union leaking after o-ring replacement
  • Visible crack or split in existing nut body

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

Before you buy — quick checklist

  • Measure your existing union connection — this nut is sized for 2-1/2 inch FBT unions with a large flange configuration
  • Inspect the union body and tail piece before ordering — if those components are also cracked or damaged, replace the full union assembly
  • Confirm your heater manifold uses a buttress thread (FBT) pattern, not a standard NPT thread
  • Check that the large flange style matches your existing union — flange diameter determines whether the nut seats correctly against the heater manifold face
  • Do not reuse a worn or cross-threaded split nut — always replace the o-ring at the same time

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

Install difficulty: Easy — DIY-friendlyTypically 15-30 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.

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