On Aug 6, 7:48*am, Phisherman wrote:
I plan to purchase a tankless water heater to replace a failing water
tank. * The current vent is a 6" diameter vent pipe. *I need a 7.4 GPM
unit (4 bathroom house with 3 showers) and considering a Rheem
GT199PVN. * I noticed some tankless heaters have two separate vent
pipes (one intake and the other exhaust). *Some have one vent pipe
with one pipe inside the other. *If I choose the later I will need an
additional hole in the side of the house (no chimney). *What are the
pros and cons of two separate pipes than just one pipe with an
interior pipe? * *Are two separate pipes functionally better than one
pipe inside the other? *I'm a bit concerned when I need to replace the
new heater (hopefully in 10+ years) that I may have to deal with
patching or resizing holes. * I've seen so many different kinds and
configurations in water heaters and vents. *Unemployed right now, I
don't have $1600 to spend on installation, I got the time to do it
myself. *Any tips on installation are appreciated.

I dont think you can do 3 showers at once with 200000 btu with full
flow heads, Plan on dual use, so if you have 4 faucets open you may be
cold in your shower, again you need to research it more, a AO Vertex
tank is great.