Open vent going into the water heater exhaust piping

I attached a couple photo’s. Would like to get a couple opinions.

The water heater venting has a secondary opening about 3’ down the line. The opening is pulling air into it at the time I checked it. I checked the water heater for down drafting and it was not doing it at the time I checked.

Though I think it could cause some downdraft? I’m unsure of this statement.

I recommended contacting a plumber for repair because it could be reducing the draw/venting at the water heater. It should be sealed off.

Anyone see anything else I’m not?

I already addressed, the improper pressure relief value. The home owner did it himself. Note how it’s aimed toward the ceiling of this basement!!!:frowning:


Stephen Rager

Hi Steven

Looks like the original flue was constructed to accommodate the furnace, the new furnace is direct vent so is no longer using the flue. Should be capped to prevent backdraft.

Thank you for the response Lawrence, I was thinking it should be capped. Any idea of the science behind it why it should be? I couldn’t find an article and didn’t see anything in the training material for it. I may have overlooked something.

I read the installation manual for a gas fired water heater. It says in big bold letters “that failure to install the draft hood and properly vent the water heater to the outdoors can result in unsafe operation of the water heater. To avoid the risk of fire, explosion, or asphyxiation from carbon monoxide, never operate this water heater unless it is properly vented and has adequate air supply for proper operation.”

Basically, any opening from the heater to the outside should be closed for safety reasons.

Thank you in advance if you find anything.


Stephen Rager

If the chimney was designed for a furnace and a water heater then the furnace removed, the chimney is now probably too large for just the water heater to draft properly.