Venting Furnace And Water Heater Together

Two appliances connected into single vent.

Venting furnace and water heater together.

The solution is to use the masonry chimney as a chase for a b vent. When installed correctly this venting arrangement works with an 80 gas furnace or lower than 80 gas water heater. I know that irc g2427 3 3 4 allows these two appliances to join into a common vent connector. To determine the main flue size refer to figure 3 and locate the square inch area of each individual flue size.

All water heater venting systems use a vent duct or pipe also called a chimney or flue to bring exhaust gases from the water heater to the outdoors. The water heater vent is located below the furnace vent at the wye. 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. This practice is common with standard efficiency 80 furnaces.

They are connected at the wye. Take a look at the two pics then. A direct vent system pulls in. Lowering the btu rating of the furnace by even half would not require a change in the size of venting.

In those cases the cold masonry cools the exhaust gases causing loss of draft as well as moisture condensation. Another potential problem with newer category i vents involves furnace and water heater flues that are connected to masonry chimneys. The furnace is induced draft the water heater natural. Let s say you have a job where you combine a furnace or boiler 8 flue with a water heater 6 flue.

If you re replacing natural draft furnace no motor assistance for exhaust gases removal with an induced forced draft motor equipped appliance and your natural draft water heater remains connected to the same chimney flue pipe make sure that water heater vent pipe connection is y and not t type. I would venture to say that the vast majority of installs in this area use 6 b vent for a combination furnace water heater. 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.