Navien Trus Head Taptite Screw M4 x 8 20006536A

The Navien trus head Taptite screw is an M4 x 8 threaded fastener supplied in S10A finish. It is used as a fixing on Navien NCB series gas boilers, where the trus head gives a wide, low-profile bearing surface and the Taptite thread form cuts its own mating thread in the parent material. It is a service fixing rather than a functional component, used to secure covers, brackets and internal assemblies.

• The head is corroded, chewed or rounded and will not take a driver cleanly.
• The thread has stripped or pulled out of the parent material, so the fixing will not tighten.
• The screw is missing after a service or repair, leaving a cover or bracket insecure.
• The screw has snapped, leaving the shank stuck in the hole.

• Confirm your boiler model and serial number against the fitment list above.
• Check the thread size and length of the fixing you are removing — M4 x 8 is not interchangeable with other lengths.
• Check the head type and clearance in the recess, as a trus head sits differently to a countersunk or pan head.
• Confirm how many fixings are needed for the job.