One of the often unsold advantages of a MVHR system is the quality of air in your house, because all the air coming into your house is filtered you have far less of the general grime floating around in the atmosphere in your house. My sister’s comment, after living in Culford road for 6 months after moving in, sort of sums up the benefit “No one told me I would have hardly any dusting to do!”
This blog from the 21 Degrees provides more details.
WHAT TO LOOK FOR when installing a MVHR system
Our best advice when choosing to fit a MVHR system; make sure you get the ducting right! Once built into the house it is near impossible to rectify bad ducts. Use round ducts as opposed to rectangular wherever possible, make sure the duct sizing is correct to reduce noise. Make sure the ducts are joined and sealed correctly. Branch systems are better than radial systems but slightly more expensive. By all means save money on a cheap unit – you can probably change it later with little effort if needed but bad ducting is a different matter.
Avoid fitting the MVHR unit in the attic, or if you do make sure there is easy access to the unit as you will need to change the filters every 6 months. We have tested systems where the filters have not been changed for between 12 and 15 months and have found a 20% drop in ventilation rates.
Make sure there is room in front of the unit for service access
I thought that was THE sold advantage. It’s certainly why I got my original and subsequent system, dating back 20 years.
No the advantage is you recover the heat from that steam from your shower or boiling potatoes before dumping the air out into the outside world. Talking Villavent - we replaced one the other month I suspect the owner now has ventilation which previously he didn’t because of the previous install and commissioning of the old unit.
Undoubtedly heat recovery is an advantage and was my second reason for buying. I am fortunate enough to be able to afford to lose heat in the ventilation air if needed, so I’ve never been troubled by condensation or lingering smells but for some the heat recovery will be more critical. Ultimately though, if you don’t want fresh air in your house you won’t but any ventilation, let alone something as expensive as whole house MVHR.
Another air quality anecdote from someone who had MVHR installed: she found that her young children no longer bring horrible winter bugs into the home.
It sounds like magic - they must still be exposed to the bugs at nursery and school? But I guess that what might be happening is that when exposed to a bug, your system either fights it off without you noticing, or you go down with a stinker of a cold. The latter might be much more likely if the 70% or so of your time that you spend at home is in good quality, controlled humidity air.
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