Navien30009933A O-Ring Kit

When working on my Navien Combi I recommend buying

There were at least 5-6 different metric sizes or all of the various o-ring requirements inside the unit.

Your Navien should come with a bag of these o-rings taped to the right hand side of your tankless but if gone buy this set. Has all the O-Rings you need for maintenance.

Like the fact I didn't need to create a list and then shop individually for these seals. The heaters will leak sooner of later, best to have these on hand .