HVAC Exhaust/intake

I came across a home where the exhaust and intake pipes were joined together just before exiting through the roof in one single pipe. I called it out because I figured the intake would be carbon monoxide.
Now I’m second guessing.
What do think?

Is this a concentric exhaust ?


From the picture it looks like a concentric vent. Very common.


Welcome back to our forum, Bryan!..Enjoy! :smile:

That is exactly what it is.

1 Like

Thanks, I assumed the intake air would be sucking in the exhaust air and make it highly dangerous.

Thanks Larry, I quit going to the forum because of all the negative and be-littleing feed back a person would have to sift through to get the answer.