Navien Boiler Leaking Water: Causes & Fixes

Repair8 min readGasBoilers.ca Technicians

Navien Boilers in Greater Vancouver

Navien is one of the most widely installed boiler and combi brands in the Lower Mainland, prized for compact wall-hung units and strong high-efficiency condensing performance. Many local homes run Navien NCB combi units or NHB heating boilers, and we service them across Vancouver, Burnaby, Surrey, and beyond.

Like all condensing boilers, Navien units are well engineered but have a number of internal components — and any of them can eventually weep. The good news is that Navien leaks tend to cluster around a few predictable areas, which makes diagnosis efficient when you know where to look.

A reminder before troubleshooting: if a leak is ever accompanied by a gas smell or a CO alarm, leave the home immediately, call FortisBC at 1-800-663-9911 or 911 from outside, and then call us at 604-359-1081.

Common Navien Leak Points

The condensate trap and drain. Condensing boilers like Navien produce acidic condensate that drains away through a trap and pipe. A cracked, blocked, or improperly installed condensate trap can leak — and because BC winters get cold enough in some areas, a condensate line run through an unheated space can freeze, back up, and overflow. This is a frequent and very fixable Navien leak.

The pressure relief valve. As with any boiler, a waterlogged expansion vessel or over-pressurised system makes the relief valve discharge. On Navien combis the compact expansion vessel can lose its charge over time.

Internal seals and the pump. O-rings, gaskets, and the pump seal can perish with heat cycling. Navien units use specific service parts, so genuine components matter for a lasting repair.

The heat exchanger. Navien's stainless heat exchangers are durable, but on older or hard-run units corrosion or a fault can develop, causing internal leaks.

Navien Error Codes and Leaks

One advantage of Navien units is their diagnostic display. Several error codes relate to pressure and water faults that often accompany a leak. Low water pressure faults frequently appear when a leak has drained the system below the operating threshold, causing the boiler to lock out.

If your Navien is showing an error code alongside a leak, note the exact code before you call — it helps us arrive prepared with the likely parts. Don't simply keep refilling and resetting the unit to clear a low-pressure code; if it keeps dropping, water is escaping somewhere and the leak needs finding.

We're familiar with the full Navien code set and how each relates to pressure, condensate, and water faults, so we can often shortlist the cause from the code and your description before we're even on site.

How We Fix Navien Leaks

Our process starts with confirming the source — condensate trap, relief valve and expansion vessel, an internal seal, the pump, or the heat exchanger. We bring the unit up to operating conditions where needed to reproduce intermittent leaks, and we read any active error codes.

From there the fix follows the fault: clearing or replacing a condensate trap, recharging or replacing the expansion vessel, renewing O-rings and gaskets with genuine Navien parts, or replacing the pump. Where the heat exchanger has failed on an older unit, we lay out honest repair-versus-replace numbers including any rebates you may qualify for on a high-efficiency replacement.

Working inside a Navien's sealed, electrically live cabinet around the gas valve is licensed gas fitter territory under BC's Gas Safety Regulation — not a DIY job.

Book a Navien Repair

Repair cost depends on the source: condensate, relief valve, and seal work sit lower, pump and expansion vessel work mid-range, and heat exchanger faults at the top. We quote after diagnosis, not before.

GasBoilers.ca is a CanroHeat Division that services Navien boilers and combis across Greater Vancouver, stocks common Navien parts, and offers same-day and weekend repair where availability allows. Call 604-359-1081 for an exact quote and to book your Navien leak repair.

Frequently Asked Questions

Why is water leaking from the bottom of my Navien combi?

On Navien units a common cause is the condensate trap or drain leaking or backing up, along with the relief valve discharging from high pressure. Both are repairable. Note any error code on the display and call 604-359-1081.

My Navien shows a low water pressure error and is leaking — what's wrong?

The leak has likely drained the system below its operating pressure, triggering the lockout. Refilling clears it temporarily, but the water is escaping somewhere and the leak must be found. Don't just keep resetting it — book a diagnosis.

Can a frozen condensate pipe make my Navien leak in winter?

Yes. If the condensate line runs through an unheated space and freezes, condensate backs up and can overflow inside. It's a common, fixable cold-weather fault. We can clear it and advise on insulating the line.

Do you use genuine Navien parts for leak repairs?

Yes — for seals, O-rings, valves, and pumps we fit genuine Navien service parts for a reliable, warranty-friendly repair. Call 604-359-1081 to book.

Expert boiler advice and service in Greater Vancouver

Call 604-359-1081 — Red Seal certified, CanroHeat Division.

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