Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)

Categories



Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.
Buy individually or both books together. Delivery is free!


powered by Surfing Waves




Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
 Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.




Ventilation: MVHR inlet and outlet positioning

Bottom of Page

1 to 11 of 11

  1.  
    • CommentAuthorblubb
    • CommentTimeOct 5th 2023
     
    Dear GBF experts,

    I am retrofitting an MVHR into a pitched roof building. The idea was to have the inlet through the tiles at the bottom of the roof in the west-facing corner, and to have the exhaust at the top of the roof with a terminal going 1 m above the roof level. See sketch attached (sorry for the bad scan quality!).

    Are there any issues with this layout?

    An MVHR installer is telling me that the inlet needs to go through the wall of the building and never through the roof, which I find hard to believe.

    Many thanks!
      Screenshot 2023-10-05 at 09.24.45.png
    • CommentAuthoran02ew
    • CommentTimeOct 5th 2023
     
    There is no need to site intake or exhaust on a wall, guidelines are both terminals to be on same elevation ( to balance pressures)and a minimum 1.5m apart ( my advice is to get further if possibly) AND make sure you are as far as possible away from SVP or chimney flues( including neighbours) with the intake!!
    • CommentAuthorborpin
    • CommentTimeOct 5th 2023
     
    I'll agree.

    Mine are a little too close together but there doesn't seem to be any issue and are also not raised at all. They are a rectangle so 2 sides are open.

    I do notice quite a lot of discharge on the slates though after 10 years.
    •  
      CommentAuthordjh
    • CommentTimeOct 5th 2023
     
    You want both terminals in a similar pressure region, so the MVHR doesn't have to strain. The roof is infamous for varying pressure depending on which way the wind is blowing etc. So I'd have thought one terminal at the ridge and one on a slope was a poor idea. Better to have them both on the same slope but with separation between them, I'd have thought. Also site them well away from edges and corners.
    • CommentAuthorrevor
    • CommentTimeOct 5th 2023
     
    Posted By: djhYou want both terminals in a similar pressure region, so the MVHR doesn't have to strain. The roof is infamous for varying pressure depending on which way the wind is blowing etc. So I'd have thought one terminal at the ridge and one on a slope was a poor idea. Better to have them both on the same slope but with separation between them, I'd have thought. Also site them well away from edges and corners.


    Totally agree and choose if you can an elevation on the non prevailing wind side. Think they would be better on the wall easier access to clean grills etc. and away from turbulence. Minimum 2m separation is the general norm.
  6.  
    As revor, the intake will have a fly mesh, which needs cleaning (leaves, general debris) at least once a year.

    An intake on the roof may well be covered with snow - the exhaust outlet unlikely, due to exhaust air direction and residual warmth. I never install intakes on the roof.
    •  
      CommentAuthordjh
    • CommentTimeOct 6th 2023
     
    Agree about the cleaning and potential blocking issue. We chose not to have fly screens on our terminals, which are high on a wall, precisely so we wouldn't need to get regular access. We have a metal screen to stop birds and rodents etc, but any insects end up on the intake filter within the MVHR. It can get fairly messy, but is designed so they can't escape to anywhere else.
    • CommentAuthorCWatters
    • CommentTimeOct 6th 2023
     
    Both our in and out come through the soffit.

    Avoid putting the inlet down wind of your boiler flue.

    I fitted a home made coarse filter to the inlet. Needs cleaning every 8 weeks.
    • CommentAuthoran02ew
    • CommentTimeOct 8th 2023
     
    Posted By: GreenPaddyAn intake on the roof may well be covered with snow


    Ubbink have a dedicated MVHR range of roof terminal (UB48, UB47 etc) these are insulated through to exterior have no fine mesh and stand 500mm+ above roof tile.

    i have recentley taken the NICEIC domestic ventilation course at Vent axia (2 day course with a BPEC acceditation) lots of guidance lots of do's and dont's but no mention of wall vents prefered to roof vents
    •  
      CommentAuthordjh
    • CommentTimeOct 8th 2023
     
    I like Ubbink's products. They generally seem to be well designed.
    • CommentAuthorblubb
    • CommentTimeOct 13th 2023
     
    Many thanks everyone for your input -- much appreciated!
    Will adjust the design by moving the exhaust lower to be at the same level as the inlet.
    The terminals are Ubbink UB49 160 mm inner diameter.

1 to 11 of 11

  1.  
Add your comments

    Username Password
  • Format comments as
 
Back to Discussions Top of Page
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press