Gas Hot Water Heater Venting

All water heaters that burn natural gas or liquid propane lp gas require a venting system.

Gas hot water heater venting.

Most tank type gas water heaters are atmospheric vent type and they are required to vent vertically and above the roof of a home. The photo below shows typical combined furnace water heater venting. Two specialized types of water heaters direct vent and mechanical vent also called power vent are exempted from this code requirement. A water heater vent pipe can be used for this venting with a hot water heater vent cap for safety reasons.

Back drafting is usually the result of an inadequate vent design. Atmospheric venting refers to a system in which exhaust from the water heater naturally rises out of the appliance s combustion chamber then travels up through a standard chimney style flue. The process of burning of the gas is called combustion and it creates heat exhaust gases including highly poisonous carbon monoxide and moisture the water heater s ventilation system removes these byproducts from the home making it a critical safety feature. With a replacement high efficiency furnace the existing vent pipe does not work for water heater only because the vent is too large.

You see this most commonly with atmospheric configurations and it means that your exhaust isn t leaving the home. 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. The venting system of the gas water heaters might consist of one or two pipes. One problem you need to avoid is back drafting.

When installed correctly this venting arrangement works with an 80 gas furnace or lower than 80 gas water heater.