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Tankless water heater exhaust vent question

codyr Member Posts: 12
Hello, I recently installed a Rinnai tankless NG water heater. I installed a direct vent setup with 2 pvc pipes, with a pitch back towards the unit for the first 10 feet. The second 10 ft of pipe runs through a set of 2 exterior walls which make the rise less severe (closer to being straight out the side of the house, possibly a slight pitch/angle back toward the unit). I then installed a low profile termination kit outside which has an exposed exhaust grill and “hidden” intake for combustion air. I notice there is some water condensate draining down the condensation line from the bottom of the unit, but I noticed a fair amount of water tricking out of the bottom of the exhaust pipe where it exits the termination kit on the outside of the house. Is this normal for a good amount of water to be exiting the exhaust outside or should the pitch be so extreme back toward the unit that ALL water from the exhaust drains down the pipe back into the unit? The Rinnai instruction diagram even shows the piping diagram with a low profile termination kit running basically straight horizontal outside with NO angle or pitch. Thank you in advance!


    EBEBRATT-Ed Member Posts: 15,614
    I don't know Rinnai specifically but most condensing appliances drain back to the appliance as dripping outside will freeze and may block the vent