Hot Water Tank Exhaust

Im new and have not taken the plumbing course yet, but i am working on my mock inspections and sorry i didnt take a pic of this issue. The hot water tank was an AO Smith natural gas fired unit located in the basement and 33 years old! It had a draft inducer fan that vented thru the rim joist and exhausted about a foot off the ground outside, at the side of a deck pad and under a kitchen window. It was covered with a heavy stainless steel cover that had vent holes at the top and marked hot. There was no chimney access in the basement. Obvious safety issues, CO and burn hazards. Is something like this allow and whats the alternative?

Hi David, so you got a hot one…


David it sounds like you’ve encountered a WH with mechanical venting. Induced draft appliance still require a chimney with natural draft to vent combustion gasses. Where was the fan installed, do you have a model of the WH? Next time always take pics or we’re just guessing based on your description.

It sounds like a direct vent water heater. You may want to look at the model number and pull up the installation instructions.

The draft device was located right on top of the heater with a sensing wire that ran down to the gas valve. I was outside when it was heating and it sounded like a dryer vent running. I only took a pic of the data plate which is attached.

Got the homeowner to send me some additional pics i should have took.

Got some additional pics from the homeowner, that i should have took. I posted them.

It doesn’t appear to be located on the deck. If you live in IPC territory the flue pipe can be as close as 4 feet under a window. Best to ask a local plumber as codes change in 30 years. As far as a safety issue let the buyers know of the hazard. That metal shroud will help to cool and displace the heat. That along with the dilution air (from basement) that’s mixed with the flue gas helps lower the temperature of flue gas at the discharge point.

What you have is a “power venter”, not a mere draft inducer. These mechanical venting devices are used to vent appliance when natural draft chimneys are not available. Look these up (and a few of their installation manuals), there is a lot of info available on them. The flue pipe on the outlet side of the venter gets pressurized and thus should be sealed not to leak combustion gasses back into the house. This is not a direct vent because the combustion air is taken from inside.


Thanks for all the info, looked at some info on these and see that they can also be installed with a pvc exhaust pipe. Im learning !

Common where traditional venting is not possible and will very depending on AHJ