Furnace And Water Heater Venting

Gas water heater vent codes standards.

Furnace and water heater venting.

High e furnaces have separate venting. The photo below shows typical combined furnace water heater venting. The conditions explained in this post also apply to the wood burning appliances. Many building codes mandate that once modified or changed all fuel burning appliance vents must be sized according to code.

Proper furnace water heater venting is an extremely important issue which depends on the performance of the house chimney chimney flue or other exhaust assemblies. Consequences of improperly assembled vent pipes problematic chimney flue deteriorating chimney walls can be sometimes fatal fire and carbon. 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. Traditional gas fired forced air furnaces produce hot combustion exhaust gasses and therefore need metal vent pipes or chimneys.

The vent for your recently orphaned water heater may not have been checked by the furnace installer. With a replacement high efficiency furnace the existing vent pipe does not work for water heater only because the vent is too large. The lower btuh of a gas water heater compared with a heating furnace or boiler will very often be unable to heat the chimney interior sufficiently to develop a draft. You have 3 gas burning appliances that must have a constant fresh air supply to support clean and complete combustion process.

The old vent pipe is too large because it served both the furnace and water heater. Because of their unique construction power vent water heaters are virtually impossible to backdraft. This is called a common vent configuration. In many cases the exhaust from the larger appliance heats up the common vent improving the flow of the water heater vent.

Power vent water heaters have quickly become the standard for newly constructed homes equipped with built in fans that push the exhaust gas out of the vent through a powered fan. It carries the solution down the chimney furnace water heater vent pipe and evaporates leaving the salt deposits on surface joints. Water heater ducts may lead directly outdoors or they may tie into a larger vent duct that also serves a gas or propane furnace or boiler in the home.