Oldgreybeard wrote: ↑Sun Sep 18, 2022 5:04 pm
Bugtownboy wrote: ↑Sun Sep 18, 2022 4:44 pm
Would love to have installed a whole house MVHR - couldn’t for multiple reasons (cost, disruption, time etc). Did install a single room MVHR (VentAxia) in the ‘family bathroom’ which does have an effect upstairs.
Not ideal, but an achievable compromise.
We were lucky, our house was a new build so I got to specify this from the start. Not cheap, but worth every single penny IMHO. I'd have it just to get rid of the hay fever, as well as having zero dust in the house. Leaving aside the big reduction in the heating bill, the things we really love about the MVHR are the clean air, the way things dry out very quickly, the freshness in every room, the fact that cooking smells never leave the kitchen and the wonderfully fresh air feeling in the bedroom. Waking up every morning to a room where the air is just clean and fresh is amazing, even now, and we've lived here a few years.
The only real downsides are related to cost. It was a fairly costly thing to fit, around 2K with all the bits and bobs. It also costs a bit to run, as the fans draw around 40W or so, and are on all the time. The filters also cost a bit, around £50 a year, bit cheaper if I buy them in bulk.
Whenever we are away staying somewhere that doesn't have MVHR the first thing we notice is the poorer air quality. Even leaving windows wide open doesn't seem to ventilate as well, probably because the ventilation is uncontrolled, so doesn't flow evenly across every room. Took some convincing to get my wife to accept that living in a house without keeping windows open was OK, but she's a convert now and the first to notice the poorer air quality when we're away somewhere. Thing she likes most is that she can hang washing up indoors when it's raining and it dries in a couple of hours.
Totally agree with your experience of MVHR. When we renovated I took the opportunity to install MVHR and at the same time changed a number of windows that were planned to be openers to fixed. I spent a considerable amount of time taping all the joints in the SIPS, putting parge coats on blockwork where buttd upto the sSIPS then sealing and taping the edges to the SIPS. We avoied as many penetrations of the thermal envelope as we could so leaving 2 for the MVHR and one for soil vent, all the drainage going out through the floor and underground. We bough tthe house and renovated whilst still living in our previous one (farm cottage solid walls half the ground floor solid onto earth (no insulation) with oil CH.
I cannot compare the heating costs (either energy wise or financial as we changed so much changing from about 1500 ft2 to 2500 ft2. The heating was changed from a combination of oil boiler (with 2 300 gallon oil tanks below the master bedroom floor

), open coal fire and 5 storage heaters to UFH from an ASHP (no gas). 2020/2021 wa around £1K electricity for the house, no EV yet.
The benefits of the MVHR seem very clear to us, much better air quality, my son had several serious asthma attacks in the old place but none since (several things changed though so not just the MVHR benefit). We have seen no mould on any walls, something that used to cause us major issues and the temperature is much more stable (probably mainly due to insulation). No more serious problems with hayfever either, given that both the previous place and the current one are surrounded by farmland (previous beans/rape/wheat) and the grass field has jsut been left for the last couple of years (not even harvested for hay) this has to be due to the mvhr system. My wife was stll a little sceptical until Covid came along but that convinced her completely (not sure why as we all had it first time round Christmas 2020 and my wife got it again Jan this year I think and hadn't been out for a month but the rest of us all tested negative). We even dry clothes in the house (have a creel below the mvhr extract in the utility room) which given the problem with exzema our son has means that we don't has to worry about pollen on his clothes, nor do we have to use the tumle dryer that much.
One change I am considering is putting a radiator into the supply side to warm the air a little in winter and hopefully cool it a little in summer. We have no heating upstairs other than UFH in the bathrooms so unless we leave the bedroom doors open the bedrooms can get quite cold.
Cost wise, I think ours was a little more expensive to fit, but running costs are similar. I found buying the fiters from Finland was much less expensive but will soon find out what brexit has done to that.