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 AO Smith direct vent venting option
Author: adkroot (NY)

Installing an AO Smith gdv40 - their non-power vented direct vent water heater- and finding that their tech support seems to not have any knowledge.

The manual allows for two 90’s- one from the vertical off the top of the unit to horizontal, and a second if there’s a need for an off-set exit horizontally out the wall.

I have an installation option that would require a 45 from the vertical off the top of the unit, a second 45 shortly after back to vertical, and then the 90 out the wall.

I would think the two 45’s wouldn’t be an inhibiting factor to the draft and intake as much as the permissible two 90’s and a 80” max horizontal run, but I don’t want to base the installation on my assumption alone. Seems they could’ve answered it.
Any thoughts on this installation?

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 Re: AO Smith direct vent venting option
Author: packy (MA)

from the internet.....
Important! Vent Installation and Termination Requirements OUTLET
Vent pipes may be trimmed (cut) for short vent installations
For vent installation less than 30” the vent restrictor is required. Place restrictor over the flue outlet on heater before installing the outlet vent pipe to the heater
Recommended installation height for the heater vent pipe should be 68” for 40 gallon models and 76” for the 50-gallon and 75-gallon models (vent height)
Offset Vent Arrangement
When replacing an existing direct vent model, the new vent pipe may drop from the minimum vent height as much as 7 1/4” to exit through the existing vent opening in the exterior wall
Vent may have one horizontal 90 degree turn before exiting through exterior wall (Do not combine both offset vent arrangements in one installation)(See examples in the installation manual)
High Rise Vent Arrangement
When vent termination is more than 80” above the base of the heater. The horizontal vent run must be a minimum of 22” from the center of the heater to the outside exterior wall surface. (See example in the installation manual)

What i read says only one 90 deg bend allowed...

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 Re: AO Smith direct vent venting option
Author: adkroot (NY)

That’s correct, one 90 per horizontal run, but according the instruction manual provided with the unit and confirmed by their technical support, two 90’s are permitted as I outlined above: one off the vertical exit from the unit and to the horizontal run, and another for an offset installation (for a non-offset installation, there’s simply the 90 off the vertical and horizontal exit straight out the wall.

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 Re: AO Smith direct vent venting option
Author: bernabeu (SC)

two 45s on the vertical then a 90 to horizontal is just fine


"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

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 Re: AO Smith direct vent venting option
Author: packy (MA)

if you can find the proper concentric 45 then you are good to go.

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