Balboa/Gecko 50mm Heater Union O’ring

The Balboa/Gecko 50mm Heater Union O-ring is a precision replacement seal for spa and pool heater unions. With one rounded edge and one thicker square edge, it creates a reliable, leak-free connection at the heater union joint — keeping your system running without interruption.

• Outer diameter: approximately 74mm
• Total thickness: 6mm (including raised edges)
• Thickness (excluding raised edges): 2.5mm
• Compatible with Balboa and Gecko 50mm heater union fittings

Balboa/Gecko 50mm Heater Union O-ring – FAQs

What heaters is this O-ring compatible with?

This O-ring is designed for Balboa and Gecko 50mm heater union fittings. Always verify your heater union size before ordering to ensure correct fitment.

What are the dimensions of this O-ring?

The O-ring is approximately 74mm in outer diameter and 6mm in total thickness (including raised edges), with a 2.5mm thickness excluding the raised edges.

What does the O-ring profile look like?

One side has a slightly rounded edge and the other has a thicker square edge. This dual-profile design helps seat the O-ring securely in the heater union groove for a watertight seal.

How do I know if this is the right O-ring for my heater?

Check your heater union size — this O-ring suits 50mm unions. If you have a 40mm union, see our Balboa 40mm Heater Union Gasket instead. When in doubt, measure your existing O-ring or check your heater's part number.