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tankless vent question

Timco Member Posts: 3,040
Cust has a takagi tankless unit, and it has single wall ss vent. The vent goes right into the unlined msrny chimney. I will pull up the takagi website and see what they say about this, but would this cause the outside of the chimney to get the white leeching stuff on the brick & in the joints of the brick? Tankless does not have a cond trap on the vent, either...The unit has 1/2" pex ( vanguard type) in & out, & I was under the understanding these units need 3/4" in & out for flow...

Just a guy running some pipes.


  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
    Don't think that will work

    You will probably experience problems from condensation. "This is a Category III appliance, and must be vented accordingly." I believe they do not approve of venting in a chimney of any kind unless it acts as a chase for the approved S/S flue piping.

    Be aware, this unit can not be combined with any other appliance in the chimney.

    The 1/2 pex may not be any issue as along as you have adequate flow rates - I believe they require a .75gpm minimum to fire. As your flow demand increases, your pressure drop will increase. If there is a high enough pressure at the unit, you may get away with the 1/2 pex if its a relatively low flow demand.

    Sounds like problems down the road. Keep your eyes open and your head clear. Read the manual.

    Good luck.

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