Navien Installation — Done Right the First Time

A complete Navien tankless or combi install includes: correctly sized gas line (often an upsize from an older 1/2" line), concentric stainless or PVC venting to a code-approved exterior termination, condensate drain with acid-neutralizer, dedicated 120V electrical, isolation/flush valves for annual descaling, Massachusetts permit, inspection, and commissioning with combustion analysis. Anything less and you will be replacing the unit early.

A clean tank-to-tankless conversion in a house with compatible gas and venting is typically a 1-day install. If the gas line needs to be upsized, venting routed through multiple floors, or condensate run to a remote drain, it can take 2 days. We walk the install with you on-site first and tell you the realistic timeline before quoting.

Often yes. Most residential Navien tankless units pull 150–199k BTU. Many older South Shore homes have 1/2" trunk lines that won't deliver that under peak demand — the unit fires but can't hit rated output and the performance disappoints. We size the gas line for the total connected load and upsize where needed.

Usually no. Navien condensing tankless units require concentric stainless (or Category IV PVC where allowed by code) venting, not the B-vent used on atmospheric gas tanks. Reusing the wrong venting is unsafe and fails inspection. We run new venting on every Navien install.

Yes, every time. Massachusetts requires a permit for gas appliance install and replacement, and the work has to pass inspection by the local gas inspector. We pull the permit, call the inspector, and finish the job with the paperwork closed. Future buyers of your house will care about that record.