(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 11 of 11

Thread: Direct Vent Question - Vent near AC Unit

  1. #1
    DIY Member philtrap's Avatar
    Join Date
    Jun 2013
    Location
    Long Island, NY
    Posts
    66

    Default Direct Vent Question - Vent near AC Unit

    Folks - My Second Question here and Thanks for your support.

    See attached photo.

    The only spot I could vent my boiler exhaust is near my AC unit. The AC unit will not be working when the boiler is working (I hope) since I only use the AC in the summer and heat (boiler) in the winter. The AC unit blows air up, but it really doesn't hit the vent. Is there a different type of end pipe I can use, or is the way it's installed OK?

    Thanks,Name:  vent.jpg
Views: 194
Size:  49.8 KB

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,434

    Default

    I don't think it will affect the a/c. It is possible that the exhaust could be slightly corrosive, and that may be an issue - it depends on whether it meets the offset requirements laid out in the manual. If it is far enough away, that effect should be diluted enough to not be an issue. But, it may be too close to either the corner or an operable window. The installation manual usually has some very specific requirements on this. The danger is that the boiler might be venting while you have a window open for whatever reason and you could be pushing CO into the house. The corner doesn't help, and the winds can do weird things around corners.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    In the Trades Tom Sawyer's Avatar
    Join Date
    Nov 2010
    Location
    Maine
    Posts
    2,945

    Default

    Its too close to the corner and the window. The installation instructions are crystal clear regarding proper vent clearances. How did you get that installation inspected and passed? If you didn't bother with the inspection process you should know that if there is ever an issue with the installation, ANY issue that causes property damage or personal injury, your insurance company will drop you like a hot rock.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

  4. #4
    DIY Member philtrap's Avatar
    Join Date
    Jun 2013
    Location
    Long Island, NY
    Posts
    66

    Default

    Tom - The Installation instructions say one foot away from the window and 3 feet from a corner. It is in compliance with that. I can run it up thru the roof. What do you think?

  5. #5
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,434

    Default

    If you've meet the manufacturer's offset and clearance requirements, and the termination is an approved type, it should be fine. You might find that leaving it there with the motion sensor on the flood lights, when the boiler is running, it may turn the lights on! In that case, through the roof may be a better option.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  6. #6
    In the trades Dana's Avatar
    Join Date
    Jan 2009
    Location
    01609
    Posts
    2,726

    Default

    Aren't you using the boiler to heat hot water? (If not, you probably should, but that's another topic.)

    I wouldn't sweat the location relative to the AC compressor- even if condensing exhaust condensate managed to finde it's way onto the AC unit, the dilution factor of rain & snow would pretty much render it neutral, now that the acid-rain issues from power generation have been taken care of. Vent terminals for direct venting have to work in 50mph gales anyway, and there's no way the turbulence on the side-stream of the AC fan would approach anything like what you'd get out of a mid-winter nor'easter or a passing tropical storm. It's a forced-draft system, it takes a HUGE amount of wind turbulence to mess it up.

    As far as clearances, in Canada to meet code you'd need to be 36" away from any operable window or door, but in the US a mere 12" cuts it unless specified differently by local code. If you're more than 36" away from the wall it would cut it even in Canada. Local codes (or the manufacturer) may have restrictions on distances to interior or exterior corners, but there's nothing enshrined in national codes on that, though parking it at an interior corner near a window could have some build-up issues at 12". There's nothing (other than glue, perhaps? :-) )to prevent you from rotating/angling the vent away from the house to guarantee that it's blowing away from the window.

    Most manufacturers want to see the combustion-air intake on the same wall as the exhaust to avoid wind-driven pressure imbalances from interfering with it's operation during those 50 mph gales, and will specify min & max clearances. If that's not a coaxial intake/exhaust vent, but exhaust only, where's the intake, and does that meet the manufacture's instructions?

  7. #7
    DIY Member philtrap's Avatar
    Join Date
    Jun 2013
    Location
    Long Island, NY
    Posts
    66

    Default

    Thanks both Jim and Dana for your input. My biggest concern was the a/c compressor unit blowing air up. I don't have hot water now since my hot water heater is new. I may add it once the hot water heater goes, so maybe I would be best to run both intake and exhaust up thru the roof right above the spot light. The intake is not finished yet, but my main concern was the a/c unit blowing up. What do you think about this (See pic below)? The vents would be at least 3 feet from any window and at least 3 feet from the wall.

    I would raise the outlets to 2-3 feet above the roof for snow.

    (See Tom, this is how a forum works)Name:  vent2.jpg
Views: 143
Size:  83.7 KB

  8. #8
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,434

    Default

    Other than two new holes in that roof, it may eliminate some potential issues (I think it will likely be okay where it is, but the roof has advantages, too).
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  9. #9
    TROJAN WORLDWIDE SALES RP MACPLUMB 777's Avatar
    Join Date
    Aug 2007
    Location
    Houston, Texas, United States
    Posts
    632
    Blog Entries
    1

    Default

    The roof top would be correct way to do the vents, depends on what windows are higher on that wall

    MACPLUMB 777

    E-MAIL
    JERRYMAC@TROJANWORLDWIDE.COM


    35 YEAR MASTER PLUMBER, HEATING, ELECTRIC, DRAINS, FIRE SPRINKLERS, WATER HEATER
    AND BOILERS SINCE JAN, 1989

    281-706-1631 7 DYS A WEEK SALES AND TECH. SUPPORT
    Trojan Worldwide Web Site


     



  10. #10
    DIY Member philtrap's Avatar
    Join Date
    Jun 2013
    Location
    Long Island, NY
    Posts
    66

    Default

    OK folks. I didn't like the AC unit blowing air up into the combustion vent, so I moved it to the roof. See the photo below. I also placed the air vent intake outside (it was inside the shed). The direction sketches always show the intake vent higher than the combustion air vent. Do you think it matters? I have a unique situation since the only way to vent the boiler is thru a shed that's built into the corner of the house. All other requirements are met. 36" away from corner walls, 12" away from windows, high enough for snow fall plus some. The vent vertically thru the shed roof is the combustion vent and the one to the right side of shed door is the intake fresh air.

    The a/c unit in the wall does not function. I now have central AC
    The central AC blow is behind the bushes. You can see it in the first photo I posted.

    Name:  photo (1).jpg
Views: 136
Size:  55.4 KB

  11. #11
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,434

    Default

    The intake and outlet are far enough apart, that I do not thing you'll have any issues. In most installations, they are run in parallel, so the height and offset is much smaller, so placement is critical.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

Similar Threads

  1. Power vent or power direct vent recommendations
    By JASchneider in forum Water Heater Forum, Tanks
    Replies: 10
    Last Post: 05-20-2013, 07:32 AM
  2. standard vent vs. direct vent
    By karter56 in forum Water Heater Forum, Tanks
    Replies: 4
    Last Post: 03-13-2013, 03:22 PM
  3. Power vent, direct vent or natural draft chimney
    By Islander in forum Boiler Forum
    Replies: 2
    Last Post: 08-15-2012, 11:51 AM
  4. Direct Vent vs Power vent
    By dtherrien in forum Water Heater Forum, Tanks
    Replies: 7
    Last Post: 12-24-2011, 08:30 AM
  5. Standard Vent (line chimney) vs Direct Vent
    By mjbardel in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 21
    Last Post: 09-13-2007, 05:23 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •