Venting Furnace And Water Heater Together

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.

Venting furnace and water heater together.

When installed correctly this venting arrangement works with an 80 gas furnace or lower than 80 gas water heater. Take a look at the two pics then. 6 flue 28 27 square inches 8 flue 50 27 square inches total 78 54 square inches. 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.

To determine the main flue size refer to figure 3 and locate the square inch area of each individual flue size. The duct may be metal or plastic depending on the type of vent system. Let s say you have a job where you combine a furnace or boiler 8 flue with a water heater 6 flue. They are connected at the wye.

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. Many homes are built with the water heater and furnace sharing the same combustion gases exhaust vent. 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.

Lowering the btu rating of the furnace by even half would not require a change in the size of venting. I know that irc g2427 3 3 4 allows these two appliances to join into a common vent connector. A direct vent system pulls in. The solution is to use the masonry chimney as a chase for a b vent.

This practice is common with standard efficiency 80 furnaces. Two appliances connected into single vent. In those cases the cold masonry cools the exhaust gases causing loss of draft as well as moisture condensation.