If it is a natural vent type water heater you can not vent it through the side wall it has to vent above the roof.
Water heater through wall vent.
This water heater is found in different homes.
The difference is that a power vent water heater pulls in combustion air from the space.
The atmospheric water heater is very common.
Most sidewall venting units include a draft inducing fan that may produce objectionable noise.
The equipment includes a multi walled plenum that uses outdoor air to cool the exhaust gases as they pass through the building wall and can be installed with zero clearance to combustible materials such as wall studs or siding.
Single wall vent pipe cannot pass through any interior wall.
Instead both systems typically expel exhaust through a pipe that runs outside through an exterior wall.
The system works solely through natural convection based on the principle that hot air rises.
Standard water heaters the most common type often use a method known as atmospheric venting.
Hot exhaust from the water heater naturally rises up through the vent and into the air outdoors creating a draw that promotes this upward airflow.
The direct vent water boiler is another type of water heater venting that you should know.
The vent consists of a vertical or upward sloping vent duct that typically ties into a common vent.
How important is noise in this case.
Exceptions may be made for non combustible walls such as solid masonry.
Single wall vent pipe cannot be used for water heaters located in attics and may not pass through attic spaces crawl spaces or any confined or inaccessible location.
Direct vent water boiler.
Oil side wall vent systems tjernlund corporation provides ss2 sideshot sidewall vent systems for oil fired heating boilers furnaces or water heaters.
Other issue is the bathroom installation which isn t permitted as well unless the water heater closet is sealed from the bathroom area air tight doors and it has a separate fresh air supply from exterior or other areas of the house that can be used for this purpose.