MHRV Duct design

[aa44]

My new house is going to have a MHRV system in it.  I am happy to install it myself but I am a bit worried about getting the design wrong, e.g. where to switch from 150mm to 100mm, effects of bends etc.

In the experience of people here:

1. Is it easy to get wrong? 

2. Would you recommend getting professional help with the design?

If the answer to the second one is yes, then, if it is allowable within the rules of the forum, is there somebody that you would recommend for the design.  I don't want to get one of the big companies involved as they seem to want to do the whole job and charge a vast sum for it.

Thanks for your help.
Andrew

[dhaslam]

The way it seems to work is  that the room vents are very small and the pipes are large so in  theory  it shouldn't matter too much  about the layout.   In practice there is  more airflow through the nearest vents and also a lot more noise as well, for this reason it is better to have the unit near the rooms that need most  air changes.  I would also double up on the vents in  the kitchen and most used bathrooms.         A self installation is  more likely to work properly.      In  my case I drew the  position of the vents  on the sketch given to the architect  who left them out of the plans given to the builder.    It meant that the vents were  mostly in the wrong place in rooms.   

[aa44]

Thank you for your very helpful reply.  I hadn't thought about the nearer vents being noisier.

Is there a right place and a wrong place for the vents in rooms?