"Tim C." wrote in message
ups.com...
Greg,

Regarding venting, the outside of the house is brick. The current vent
is on the roof. I realize that a hole could be knocked in the brick
for side vent, but I prefer to use the existing path out the roof, just
a bigger vent.

If we put in a 4" vent, and later some year down the road get anothe
water heater that only need a 3" vent, can we use the 4" venting system
with that heater? I assume that would be OK, just not the other way
around.

Thanks.


Down the road you may be able to vent a smaller heater through 3", but it
will depend on the heater. Most manufacturers will include venting
requirements in with the heater.

How much trouble is it going to be to replace the 3" vent with 4"?
If the vent goes up through an attic area it would be pretty easy. If it
goes up through finished space you may have a problem! "B" vent typically
needs 1" of clearance to combustibles. So 3" will fit in a minimum 5" wall
cavity. 4" will need a minimum 6" wall cavity. It probably will not be as
easy as stuffing 4" vent up where the 3" vent was! You may be ripping out a
wall to install the vent!
A power or side wall vent may be a less expensive option, but power vent
heaters can be troublesome, so I would avoid one and go with a natural draft
heater like you have.
Greg