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4.0KW 230V Flow Thru Heater 73994 240V - Bubbles Supply

4.0KW 230V Flow Thru Heater 73994

Part #: 73994

$699.07
In stock — ships today
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Also replaces

73994
1-year warrantySame-day ship before 3pm CTPerfect Fit Guarantee30-day returns

About this heater

This 4.0KW 230V flow-through heater assembly is designed for Caldera Highland series spas, delivering reliable heating performance with stainless steel construction. Operating at 230-240V with 4000 watts of heating power, this OEM replacement part ensures your spa maintains optimal water temperature efficiently. The flow-through design allows water to circulate directly through the heating element for consistent heat distribution.

Bubbles Supply guarantees this heater is an exact fit for your Caldera spa, backed by our 1-year warranty for complete peace of mind. We ship same-day on orders placed before our cutoff time, getting your spa back to perfect operating condition quickly. This genuine OEM part addresses common heating issues including no heat (NH) and overheating (OH) problems. Always verify your existing heater's specifications and voltage requirements before installation to ensure proper fitment.

Exact part number

73994

Save this for ordering or warranty claims

Also known as / Replaces

This part replaces or is interchangeable with:

  • 4KW heater assembly
  • 73994
  • flow-through heater assembly
  • inline heater
  • spa heater element

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

Technical specifications

Voltage
230-240V
Port type
Flow-through (inline)

Plumbing notes

  • Port type: Flow-through (inline)

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:

  • No heat or spa won't heat up
  • Spa displays OH (overheat) fault code
  • Spa displays HH (heater high limit) fault code
  • Heater element burned out or failed
  • Spa water temperature drops and won't recover
  • Visible corrosion or failure on existing heater assembly

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

Before you buy — quick checklist

  • Confirm your spa is a Caldera Highland series model before ordering
  • Verify your spa runs on 230-240V — do not install on a 120V system
  • Match the wattage (4.0KW) to your existing heater label before purchasing
  • Inspect your heater unions and plumbing connections for wear or damage before reinstalling
  • Check whether your control board or high-limit sensor also needs replacement if an OH or HH fault persists after heater swap

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

Install difficulty: Medium — Some experience neededTypically 45-90 minutes

Warranty

1 year 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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