You can do a quick check of your chimney to see if it meets an old rule of thumb and some of the current codes.
Can you vent a hot water heater through the wall.
A power vent water heater will cost about the same as a tankless heater and avoiding a through the roof vent can make the difference in a tankless installation being affordable or not.
Photos go a long way.
If it is a 3 inch diameter pipe the inside cross sectional area of the chimney flue liner should not exceed 49 square inches.
Direct vent water boiler.
Yes you can vent a gas fired water heater out of the wall if it is either a power vent unit.
Illustrations of proper gas fired water heater venting using type b double wall vent pipe through a roof above or through a chimney below include details for the flue vent connector such as the requirement of a minimum vent connector upwards slope of 1 4 per foot of horizontal run.
Without knowing the water heater type vent type location and type of termination no one can give you a more definitive response.
The direct vent water boiler is another type of water heater venting that you should know about.
Measure the diameter of the exhaust pipe leaving your hot water heater.
The system works solely through natural convection based on the principle that hot air rises.
Before properly venting a gas water heater it s important to determine if there is a proper natural draw.
Two specialized types of water heaters direct vent and mechanical vent also called power vent are exempted from this code requirement.
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 difference is that a power vent water heater pulls in combustion air from the space around the appliance then uses a fan to propel the exhaust through the vent.
Discover the differences between single wall vents.
The air that is used for combustion will come from the water vent this vent will either through the roof or from the outside of the wall.
They do make two models of power vent units one is called a direct vent power vent as bob harper pointed out it draws its combustion air from outside unlike a standard power vent unit which burns its combustion air from the dwelling.
The vent consists of a vertical or upward sloping vent duct that typically ties into a common vent.