# Flue capacity



## plumberkc (Jun 23, 2011)

I'm trying to determine if a client can safely add a second heater. 

I don't remember the difference between fan and nat, or fan/nat. I believe the house is just natural but I wanted to be sure.


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## plumbdrum (Nov 30, 2013)

Are you asking if you can mix natural draft and fan assisted? Is so yes, I'm assuming you have a furnace, and you want to add a 2nd WH. Check your charts


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## plumberkc (Jun 23, 2011)

Yeah I'm trying to figure out which chart I should be using. There is a furnace and an existing water heater now. 

I guess I'm just asking if the furnace is considered fan.


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## plumbdrum (Nov 30, 2013)

Start with your chimney type, then are you going to use a common vent connector, what material are you using for that, single wall, bvent? Total BTU's going into chimney, chimney height. You can't just pick any chart


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## plumberkc (Jun 23, 2011)

It's a newer home with a type B double wall vent. There are two appliances, both of which are using a single wall metal connector. 

The vent height is 30' and the flue is 6". I believe my btu capacity is 286,000.

Note: circle on upper chart is from a previous job.


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## plumbdrum (Nov 30, 2013)

Looks like your chimney would be big enough


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## plumbdrum (Nov 30, 2013)

To get an example on how to size to refresh your memory go to annex g


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## plumbdrum (Nov 30, 2013)

I'm screwing up calling it a chimney also, it's your common vent connector all the way up


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## HonestPlumb (Jan 25, 2015)

That's OK plumbdrum, we all call it a chimney. Don't know why they have to use ridiculous terminology !


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