There has been quite a debate about this so i thought i would see what you all have to say. Please see the picture. Ok, basically we have 2 water heaters, both have 3’’ exhausts going out of the water heaters into a 4" “Y” connector and then back to a 3" reducer and then to the main exhaust which appears to be a 8". Between my company, sellers, buyers and agents we had a wide arrange of opinions. I want to know what is NACHI’s stance on this? Two plumbers (both master plumbers) state “this is fine”. One plumber states “you can never reduce a 4’’ to a 3’’ as you can only increase and never decrease”. Last plumber stated. "you cannot connect 2 exhaust into a “y” connector… Ok. Let me hear what you got…
Sound correct to me.
I agree with Roy
Duct work and plumbers don’t mix.
Roy and Gary are both right.