I'm replacing a 40 gallon gas water heater with a tankless version (Aquastar
250sx). As the water heater and furnace are within 5 feet of eachother in
my laundry room, I WAS going to just angle the existing vent that is
connected to the hot water heater now. It is a 3" galvanized vent. It is
connected to the vent which is used by the furnace (which looks like 4"),
then the pipe going up into the ceiling and out the roof looks closer to 6".
However, now that i get the new heater, it says that it needs stainless
venting and can not be vented in common.
Now for my question, and i know it sounds stupid, but just wondered what
everyone else is doing. Can i just use that vent or atleast that stack
that goes up through the roof and change it all to stainless? Or is there
any way to do this without running a new exhaust? If there isn't, what is
better to do, a horizonal or vertical exhaust? The heater is being mounted
on an outside wall so i believe the horizontal wouldn't be that hard, but
are there any issues with my siding being vinyl? The previous owner melted
some by placing the grill a little too close, i can't imagine that this
thing is going to fair any better.
Finally, it has the option to use in room combustible air or have a seperate
vent run for that, what are the advantages/disadvantages or doing it either
way. I live in Central New Jersey if it makes a difference.
Thanks in advance for your help.