Navien 20018744B – Back-Up Ring – Polyamide 6.6, 18.5 x 21.6 mm

The Navien 20018744B Back-Up Ring is a genuine OEM part designed to provide structural support for seals and O-rings in high-pressure areas of Navien water heaters and boilers. Made of durable Polyamide 6.6, it prevents deformation and leakage by reinforcing joint stability. This part is commonly used in systems requiring robust seal retention, especially where thermal expansion and mechanical stress are present.

Compatible with a wide range of Navien units, including:

• NPE Series tankless water heaters
• CR/CC Series condensing water heaters
• NCB, NCB-ASME, CH, and CH-ASME Series combi-boilers
• NR/NP Series condensing tankless water heaters

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