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Heater Union Tailpiece 3" 42-2373-K - Bubbles Supply

Heater Union Tailpiece 3" 42-2373-K

Part #: 42-2373-K

$21.33
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1-year warrantySame-day ship before 3pm CTPerfect Fit Guarantee30-day returns

About this union/fitting

The HydroQuip Heater Union Tailpiece 3" (part #42-2373-K) is an essential plumbing component that connects your spa's heater assembly to the main circulation system. This OEM replacement part fits HydroQuip heater systems and features 3" male buttress thread (MBT) on one end and 2" slip connection on the other, ensuring proper water flow between your heater and spa plumbing.

Built to HydroQuip's exact specifications, this tailpiece restores reliable operation when replacing worn or damaged heater unions. At Bubbles Supply, we guarantee this is the exact fit for your system and ship same-day from our Canadian warehouse. Every heater union tailpiece comes with our 1-year warranty for complete peace of mind. Before installation, always verify your existing tailpiece dimensions and thread type to ensure proper fitment with your spa's heater configuration.

Exact part number

42-2373-K

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Also known as / Replaces

This part replaces or is interchangeable with:

  • 3-inch buttress tailpiece
  • heater manifold tailpiece
  • Heater union tail piece
  • union tailpiece

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

Technical specifications

Union size
3 inch MBT (male buttress thread) x 2 inch slip

Plumbing notes

  • Union size: 3 inch MBT (male buttress thread) x 2 inch slip

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:

  • Water leaking at the heater union connection
  • Cracked or broken tailpiece causing loss of prime
  • Stripped or damaged buttress threads preventing a watertight seal
  • Persistent high-heat or overheat faults caused by restricted flow through a failing union
  • Spa won't hold pressure due to failed heater plumbing fitting

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

Before you buy — quick checklist

  • Confirm your existing tailpiece is 3-inch MBT on the heater side — do not assume based on heater model alone
  • Verify the pipe connection on the plumbing side is 2-inch slip (not threaded or a different diameter)
  • Check that your heater manifold accepts a standard HydroQuip union tailpiece — look for the HydroQuip part number on the existing piece
  • Inspect the union nut and o-ring at the same time — replace both if either shows cracking, deformation, or discoloration
  • Confirm whether you need just the tailpiece or the complete union assembly (nut + tailpiece + o-ring kit)

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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