Heating, Air Conditioning, Fridge, HVAC/Hvac


What size chimney liner is required in a masonry chimney to vent a125,000 gas btu fan induced furnace and a 40 gallon gas hot water heater

Hi Rick, The liner size should match the exhaust pipe on your furnace. Most hi- efficiency furnaces are 3". You will have to find your local code about connecting the hot water heater into the same liner. I would vent the hot water heater separately. If the cap or liner would become blocked the furnace would vent out at the hot water tank.

Hope this helps.

Heating, Air Conditioning, Fridge, HVAC

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Jim S.


I can answer questions on gas or electric furnaces, ac units and heat pumps. I don't work on boilers,chillers,or home appliances.


I have been in the HVAC trade for over 35 years. For the past 15 years I have owned my own business. I am semi-retired so I can answer questions in a timely manner.

I attended trade school for 5 years on weekends and evenings. This was very hard to do, but well worth it!

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