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: Commissioning an MVHR (quick and dirty)

Bottom of Page

1 to 14 of 14

  1.  
    • CommentAuthorSimon Still
    • CommentTimeNov 22nd 2015 edited
     
    I am renting an anemometer to set the system up properly but it's going to be a week or so until it arrives. However, we've now been living in the new house for 10 days and a sealed house with two people living and washing is resulting in humidity sitting at 70%+ and we have condensation dripping from the roof lights.

    I want to get the system running even if imperfectly today and I've suddenly realised my knowledge is a bit lacking.

    The MVHR unit is a sentinel kinetic plus. The performance graph is on page 9 of

    http://www.vent-axia.com/files/pdf-downloads/439817Q_4.pdf

    The system design shows that I need a "normal" extract rate of 228m3/hr. Am I right in thinking that I should be assuming a static pressure of about 150Pa running the unit at the default setting of 30%?

    I need the static pressure to set the flow rate on the outlets. The airflow 125mm vents have a little graph on them and can supposedly be set up just based on this and a number of turns from shut. However, the x axis in m3/hr doesn't seem to go low enough - most of my rooms need to be set to about 23m3/hr but the x axis starts at 50

    https://www.heliosventilatoren.de/mbv/ktva_poly_002_1210.pdf
    • CommentAuthorCerisy
    • CommentTimeNov 22nd 2015
     
    How strange Simon that our new discussions landed at the same time - I'll watch your posting with great interest, although I guess you have loads more info than I have (our designer disappeared after we purchased the system!)

    Regards, Jonathan
  3.  
    Great. The graph on the inlet valves kvz125 has both the values I need off the axes

    https://www.kwleasyplan.de/cm/docs/mbv/ktvz_poly_0908.pdf
    •  
      CommentAuthordjh
    • CommentTimeNov 23rd 2015
     
    Posted By: Simon StillI want to get the system running even if imperfectly today and I've suddenly realised my knowledge is a bit lacking.

    Just turn it on and use your ears and your hands in front of the outlets to judge flow rates. You should easily get it working well enough to fix your humidity problem and make life comfortable.
  5.  
    Thanks djh.

    It's made a big difference after 2 days. Towels drying quickly is a sure sign
    •  
      CommentAuthordjh
    • CommentTimeNov 25th 2015
     
    That's great. Now you can figure out the 'proper' set up at your leisure :bigsmile:

    Cheers, Dave
  7.  
    Update on this.

    I rented an Anemeter from BPC Ventilation and have spent a day or so running around the house.


    The system is installed with semi-rigid ducting which means there doesn't seem to be any major impact of an adjustment on one vent on the others (as expected). However, it was impossible to get the specced flow in some rooms (fully opened) and extract in some others (vent fully closed) so I needed to adjust the specced figures slightly.

    The Vent Axia Kinetic lets you set power %age for the supply and extract separately and I needed to set these differently to get the overall system balanced. Of course the amount of 'offset' of the fans varied by power -

    I ended up with Low 18% extract/23% supply, Normal 33/38, Boost 55/65

    One question remaining - is there any guidance for what level a 'boost' or high extract rate should be? At the moment it's set at 68L/s (against a normal level of 50 L/s)
    •  
      CommentAuthordjh
    • CommentTimeFeb 15th 2016
     
    Posted By: Simon StillI rented an Anemeter from BPC Ventilation

    I'm curious how much it was if you don't mind me asking, and did it have a certificate?
    • CommentAuthoran02ew
    • CommentTimeFeb 15th 2016
     
    not the answer you want, but if theses rooms are the farthest from the unit it can mean there inst enough air flow in other words they may have needed 2 pipes not one? also as you tune the system nearest to farthest you will lose/gain pressure to the remaining vents , thats the time to adjust the fan speed and restart at the begining
  10.  
    Posted By: an02ewnot the answer you want, but if theses rooms are the farthest from the unit it can mean there inst enough air flow in other words they may have needed 2 pipes not one? also as you tune the system nearest to farthest you will lose/gain pressure to the remaining vents , thats the time to adjust the fan speed and restart at the begining


    Yes - it was the farthest room *but* that's also the smallest room so I figured a little less input wouldn't be an issue (single bedroom not double bedroom). More of an issue was limiting extract rate in rooms closest to the manifold - the utility room and WC are both slightly higher than design, so I had to lower the kitchen to compensate and maintain overall rate)

    I worked round the whole house about a dozen times in all.
  11.  
    Posted By: djh
    Posted By: Simon StillI rented an Anemeter from BPC Ventilation

    I'm curious how much it was if you don't mind me asking, and did it have a certificate?


    I think about £40, no certificate supplied but they could email that.
  12.  
    I hired an anemometer from Speedyhire for £35 per week. What certificate do you mean? Do you mean from the guys dealing with the commissioning of the MVHR or a certificate for the anemometer from the hire place.
    •  
      CommentAuthordjh
    • CommentTimeFeb 15th 2016
     
    Thanks chaps. The calibration certificate for the anemometer.
    • CommentAuthoran02ew
    • CommentTimeFeb 15th 2016
     
    check equipment first, remembering the tester needs calibrating to the cone being used. On the bag that the supply/extract vents came in you will see a chart detailing the rotations open from zero depending on the rough room size . this is a good starting point and will allow you to start the full balancing (surprisingly the vent are never more than 2/3 full turns open) if after doing this you cannot get the desired flow rate from your first vent then you will need to speed up that fan, remember supply and extract fan could be at different speeds to accommodate the different pipe runs and bends.
    .

1 to 14 of 14

  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