Mikepier wrote:
I have a 75 gal water heater with a 4 " vent going into a chimney. If
I wanted to add a second water heater, what would be the proper way
to vent both into the same pipe? Could I just add a Y and vent both
through the same pipe going into the chimney?

Reason I wanted to add a second water heater is that this is a
multi-family house and I wanted to split the demand for HW by zoning
off the apts with 2 water heaters
By the way, my steam boiler vents into the chimney from the opposite
side with its own separate vent pipe.

You may also want to try posting this question on the
http://www.heatinghelp.com/ website;



in particular, on their forum called "The Main Wall" at

http://www.heatinghelp.com/forum-cat.../THE-MAIN-WALL .



You could post your question there anyway, but the fact that you have steam
heat also helps since they specialize in steam heat information and
discussions.



I posted there about chimney issues and codes in the past and got great
responses.