Tankless water heater vent pipe dripping in Greater Vancouver

Seeing water drip from the vent pipe of your tankless water heater can be alarming, but on a high-efficiency condensing unit a little moisture is part of normal operation. The key is knowing where the water is coming from. Here is how Greater Vancouver homeowners can sort it out.

Where the water usually comes from

A condensing tankless unit cools its exhaust enough to extract extra heat, which produces acidic condensate inside the vent. That condensate is supposed to drain through a built-in trap and condensate line. If that drain or trap is blocked, condensate can back up and drip from vent joints. Dripping can also come from rainwater entering a poorly terminated vent, or from a loose or improperly sloped vent connection.

Our damp climate means condensate volumes stay high year-round, so a marginal drain that copes in summer can overflow in a wet Vancouver winter.

• Normal condensate that should drain through the trap and line
• A blocked condensate drain backing up into the vent
• Rainwater entering through the outdoor termination
• Loose joints or improper vent slope

Why a dripping vent should not be ignored

Condensate is mildly acidic, so dripping onto the unit, the floor, or surrounding materials can cause corrosion and staining over time. Water at vent joints can also signal that the venting is not sealed or sloped correctly, which affects safe exhaust of combustion gases. Persistent dripping is a prompt to have the venting and condensate system checked.

• Acidic condensate can corrode the unit and surroundings
• Dripping at joints may mean the vent is not sealed or sloped right
• It can point to a backed-up condensate drain

Safe checks and when to call

You can look at where the drip originates and check that the condensate drain line is not kinked or obviously clogged downstream where it is accessible. Beyond clearing an obvious external blockage, resealing or re-sloping the vent, servicing the internal condensate trap, and any combustion-venting work belong to a licensed gas technician. If you smell exhaust indoors or suspect gas, leave the home and call your gas utility's emergency line first.

• Identify whether the drip is at a joint or the condensate line
• Check an accessible condensate line for obvious blockage
• Vent sealing, slope, and trap service require a licensed technician
• Smell exhaust or gas indoors? Leave and call the gas utility first

Frequently Asked Questions

Why is water dripping from my tankless water heater vent?

On a condensing unit, acidic condensate forms in the exhaust and should drain through a trap and line. Dripping usually means that drain is backed up, the vent is not sealed or sloped correctly, or rain is entering from outside.

Is a dripping vent dangerous?

The drip itself is usually not an immediate hazard, but acidic condensate can corrode parts, and a misaligned vent can affect safe exhaust. Have it checked promptly.

Can a blocked condensate drain cause this?

Yes. If the condensate trap or line is blocked, condensate backs up and can drip from vent joints. Clearing an accessible blockage may help, but the trap should be serviced by a technician.

Should I keep using the heater if the vent drips?

It is best to have it inspected soon. If you ever smell exhaust or gas indoors, leave the home and call your gas utility's emergency line before anything else.

HeatLand Heating & Cooling is a licensed and insured, TSBC-certified HVAC company serving homeowners across Greater Vancouver. Our technicians diagnose the real fault, explain your options in plain language, and complete the work safely and to code.

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