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Common venting through side wall

Rankin Member Posts: 26
I've ran into a job where two Reznor UDAP-60's are common vented through the sidewall. I can't find anything where it says NOT to do it, but I'm having a hard time finding out if it's acceptable. The vent connectors are 4" and the common vent is increased to 5".

Any input, good sir?




  • Tim McElwain
    Tim McElwain Member Posts: 4,621
    Are these Reznor

    unit heaters hung above the floor and going out the side wall with standard galvanized single wall or type "B" double wall? If so they can be installed in accordance with NFPA 54/ANSI Z223.1 National Fuel Gas Code venting charts. Are you familiar with that code?

    NFPA 54 will give clearances to combustible along with correct vent sizing charts.
  • Rankin
    Rankin Member Posts: 26

    Different code, i'm sure the standards are somewhat the same. Vent connectors are 4" single wall galvanized, vent is 5" double wall type b-vent. Just never seen it before, and all the venting charts in the Canadian code show a vent height, which in the case of sidewall would be 0, or less because because Reznor actually specifies a 1/4" per foot drop on horizontal venting to allow for the removal of condensate. The Reznor manual does show a sidewall vent per unit, but not a common side wall vent for two.
  • Tim McElwain
    Tim McElwain Member Posts: 4,621
    In Canada B149

    I believe is code. If I am understanding you correctly this is teminating at the side wall? If so then that is not correct unless manufacturers specs allow it.

    I previously thought you had a single wall common connector going to a vertical "B" vent outside.
  • Tim McElwain
    Tim McElwain Member Posts: 4,621
    edited November 2010
    Just looked up this unit

    at www.rezspec.com it calls for a special venting manual for the unit which I could not find listed anywhere on the web site.

    UDAP-CV Form I-UD-V-CV

    Optional Common Vent Installation

    (Model UDAP heater must be

    equipped with Option AV6.)

    Label with BLUE

    I would try that web site and get in touch with Reznor before you go any further just to make sure there is not some special venitng setup for this unit.
  • Rankin
    Rankin Member Posts: 26

    Thanks, Tim.


    is the link to the CV manual, and there it states that common wall venting is only permitted on units designated with CV and that they must be vertical.

    I guess I didn't look hard enough, you're direction is what I needed! For the record, it is not me installing them, but another contractor on a building I'm doing work in.
  • Henry
    Henry Member Posts: 998
    Common venting

    Cat 1 apliances can only be vented verticaly. B149 does not permit combined sidewall venting of any apliance. We have a Work Group looking into common venting of Cat IV appliances as NFPA 54 does not prohibit it and some European manufacturers do it.

    All venting must be according to the manufacturer's certified instructions and gas code which ever is more severe.

This discussion has been closed.