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My Goodman furnace manual mentions that the intake and flue pipe must terminate "in the same atmospheric pressure zone". Would there likely to be any atmospheric pressure difference between a shorter intake pipe terminating at the front of a house, at 3 feet elevation, and a longer vent/flue pipe terminating at the back of a house, at 10 feet elevation?

In the manual and in many installations I've seen, both pipes run and terminate nearby but in my case it would be easier for the pipes to take different routes and terminate in different places. I have a brick rowhouse that shares walls with the rowhouses on either side of it, so terminating the flue to code is tricky, but doable - if I can avoid taking the same route for the intake pipe it would save me time.

Any thoughts appreciated!
 

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They should be in the same area if Goodman recommends that.

There are a few manufacturers with a few models where that is not so critical ( Carrier and Lennox have them ) but I have never heard of Goodman allowing that.

You will get pressure switch tripping problems and no heat if you don't follow their specs EXACTLY.

Where I am the gas inspectors use the install manual and follow the install pics exactly and allow no deviations. They will red tag it and shut you down.
 

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I could detail the pressure differences for you but no inspector would or could accept that explanation. As Yuri said, they follow the book as you must.

As a side note, if you are 6' tall there is a 20 Pascal pressure difference between your nose and your toes, so elevation does make a difference.

Bud
 

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Elevation is not a huge issue as we can vent them at ground level or out a chimney on a 2-3 story house.

Total effective length of pipe is what needs to be calculated. Feet of pipe plus type of and how many elbows used adds to the total and you must be within Goodman's specs.
 

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If you want to use a concentric then it should be supplied by Goodman to meet their specs.

A generic one may have too much back pressure/resistance and cause pressure switch tripping problems.

Newer furnaces are a lot smaller and more finicky when it comes to that.

I don't like them as the intake plugs easily with leaves and spiders webs and debris and sometimes snow.
 
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