A few months ago, I had my old 50-gallon conventional gas water heater replaced with a tankless model. The plumber connected a 2 to 2.5-inch PVC pipe to the existing vent in the ceiling of my attached garage and sealed any gaps with foam. Recently, I noticed a small drip coming from the elbow of the PVC vent. It's not a lot of water, but I placed a basin there to catch it. My contractor thinks it's condensation, but I don't think it should be happening. Does anyone know why this moisture is appearing? I wish I could share a photo for clarity!
2 Answers
Just a heads up, tankless water heaters usually require direct venting due to the acidic condensate they produce, which can damage traditional chimneys. The design often leads to cooler exhaust temperatures, causing more condensation outside the pipe.
Yeah, it sounds like it’s likely condensation. Burning gas produces water vapor, which can condense in the vent, especially if it’s cooling down too much. I’ve had a similar issue with my exhaust pipe – it rusts if I don’t keep up with maintenance.
I would have thought the condensation would be inside, not on the exterior of the pipe, like a car exhaust. ?