Hello - Here about MVHR

[FlibbleWibble]

Putting an MVHR into house refurb (not passive or air tight!) and have various questions I hope people can help me with hence joining.

[Redbeard]

Welcome.

 

Some people would say MVHR is an essential adjunct to a very a/t house, while others would say simply don't bother with it unless you are looking for a/t of less than 3ach. Others still say that it can make sense at up to 10ach provided you've got a low specific fan power (SPF). And lastly some with respiratory issues say 'MVHR massively increased my comfort in the house'. Choose your explanation, but you are doing it anyway, so I hope it goes easily, and don't forget the attenuators (and smooth ducting if you can).

[SteamyTea]

Nothing wrong, in principle, with adding controlled ventilation to a house, what you will not get with MVHR, in a leaky house, is much benefit from the HR part.

If you are currently, or still planning the refurbishment, make airtightness your first priority, it cannot be done as an afterthought.

[FlibbleWibble]

Thanks,

I hope that modern building methods will put us somewhere reasonable on the a/t but this is mostly about having controlled fresh air ventilation.  Probably best not to mention the unit itself is outside the main thermal envelope…

[CADjockey]

Haven't been on the forum for a while, been living the dream! 😆 Anyway, we were not convinced by having MVHR, but did put it in in the end.
Yes ours is a new build so thermally better than older property but I did it mainly for the air quality and because It irked me to install trickle vents 
in otherwise perfectly good and 'sealed' windows. I changed the filters for the first time last week (6months) and it was a revalation what we are 
avoiding breathing in. It's good for common dust allergies. No heating on and MVHR running on Cool, air in and out at about 20.5 degrees.