I dabbled with MVHR retrofit in our old bungalow and concluded it was very hard to get right. Pipework and unit in a cold place (attic) was hard to insulate sufficiently to stop internal condensation and gunge. Also issues with noise, and having stayed in a few places with it (Switzerland and Finland amongst others) it has never been what I'd call "silent" if you are sensitive to that kind of thing. For something so apparently simple, it really needs leaving to experienced designers.
PIV was the solution to the bungalow ventilation issues, but obviously not as energy efficient.
In our new build, I'm currently happy with good insulation, ASHP, reasonably tight build and trickle vents / local extraction when needed. At some point it would be interesting to increase the airtightness and fit some kind of MVHR, ideally something fitted inside the warm envelope with minimal pipe runs. I always wonder if it really needs so many inlet / outlet ducts, or could work with just a few well positioned ones to create air movement.
question - those with whole house MVHR - how do you ensure the ducting is kept clean ?
There are filters either side of the heat exchanger so the supply air should be clean. I've only done one 'pipe' clean in 10 years and didn't find much - the 75mm flexi pipe has a smooth and supposedly anti-static surface so stuff shouldn't stick to it. But I ran a duster around each of the extract valves and then disconnected each of the pipes at the manifold and attached a vacuum cleaner. the bathroom extracts had a bit of dust around the inlets and the kitchen one was a little greasy but I was supriised in both cases how clean they were (we do have a very effective recirculating cooker hood, always use it, and don't do a lot of very greasy fried meals)
The one that worries me more is the big inlet pipe ahead of the unit - mines a lot longer than advisable. But I'm not sure what the real risk is - it's air from outside, you're breathing it anyway.
watched the rest of the prog last night - The biggest take away for me was those prefab houses.
Those looked the bomb. Id easily have one of them so long as it wasn't considered non standard construction/un-mortgageable.
- Whats the process for becoming a Standard construction/mortgageable* - does anyone know ? Id argue a lot(not all) of modern new builds have been streamlined and "optimised" so much that they should be in that category - last lot of wind which wasn't even that bad was ripping roofs to bits on the new builds round here The compo faces in the local rag were strong. - then the snow was ripping the facias and gutters off..... Lets not forget the Stewart milne kepplestone flats with a maximum occupancy of 5 (or the floor collapses)
*I get this wasnt their target market ..... but i have seen folk stung by SIP building previously which leaves me a little hesitant
Those ceramic core in/out fans look interesting but the small fast fan will be similarly noisy to an ordinary extractor fan. The reason modern ASHPs are quiet (compared to those of 10+ years ago that contractors love to warn you about) is their large, relatively slow fans.
We bought a 200 year old small stone farmhouse in need of complete renovation, spent a year replacing all roofs, doors, windows and everything inside (we kept the original joists and beams and fireplace with logburner). Insulated to the max, inlaid PV panels, ASHP with large buffer, underfloor pipework everythere, all spec'd carefully and now have 5 years of comfort with low bills. No MVHR (space) and no battery currently (economics didn't make sense back then, maybe now they would). Not rich, we lived in a caravan in t'farmyard for a year whilst the local builders rebuilt for us, and paid an amount reflecting the near-derelict starting point. Some things could fit sensibly into a lesser refurb, some not; I can have a think which are which if there's interest.
Those ceramic core in/out fans look interesting but the small fast fan will be similarly noisy to an ordinary extractor fan. The reason modern ASHPs are quiet (compared to those of 10+ years ago that contractors love to warn you about) is their large, relatively slow fans.
that’s a good point. One of the other nice things about me he is a centralised fan. The noise of extractors in bathrooms really bugs me now. Mvhr isn’t silent but it’s never noticeable when you’re going stuff. (It’s rare we don’t have radio on) and goes to very low mode at night.
If I was in the position to build another house, I’d certainly look at MVHR with blown air heating rather than an ASHP and wet system as would prefer a more constant temperature throughout the house and manage humidity better. With a portal roof / no attic there’s no room to retro-fit. Our house is ‘non-standard’ construction being steel portal, timber frame, wooden cladding and metal roof. We’re relatively exposed and survived a number of 90mph+ storms without incident. Currently waiting for a quote for solar panels plus battery- my heating guy reckons it’ll save about £1500/year which is my entire leccy bill.
On MVHR in old properties I saw a very nice set up last year in a house in Chorltonville. MVHR main unit was in the loft. The commissioning company made use of existing chimneys to take ducting to some rooms. For others they went down inside, for example, existing built in cupboards. Very neat.
I think it is ‘semi-detached house in conservation area’ on this page of customer stories. https://yourhomebetter.co.uk/customer-stories
If I was in the position to build another house, I’d certainly look at MVHR with blown air heating rather than an ASHP and wet system as would prefer a more constant temperature throughout the house and manage humidity better. With a portal roof / no attic there’s no room to retro-fit. Our house is ‘non-standard’ construction being steel portal, timber frame, wooden cladding and metal roof. We’re relatively exposed and survived a number of 90mph+ storms without incident. Currently waiting for a quote for solar panels plus battery- my heating guy reckons it’ll save about £1500/year which is my entire leccy bill.
It's pretty rare even in PassiveHaus certified buildings to be able to rely on MVHR for heating
https://www.earthwiseconstruction.co.uk/service/heating-cooling-with-mvhr/post-heating-with-mvhr/?
For a constant temperature throughout the house I don't think you can beat wet UFH run at a very low temperature (weather compensated, but only a few degrees above target). But it's a lot 'gubbins' to install. I'm thinking, with the increase in extreme heat, Air-Air heat pump is going to be the best future solution as with some solar panels you can have guilt free (and bill free) air conditioning when you need it.
Some friends of ours have a passive house but it's small and open plan but they manage with a single unit. What I don't know is how warm all the rooms are in winter. What I still don't understand about our own house is that our bedroom is reliably the warmest room in the house, despite having the underfloor heating turned off.
Yep, loads of gubbins for wet system heatpump - we made a 2x2m plant room for it, off the end of our adjoined garage. Also, we were removing every floor and insulating anyway so the pipework was just one extra step of that process. Expensive too, 15k+ but nearly half of that came from a grant over 5 years.
It's great for an efficient constant temp, but no good for quick heat in the evening. We have a logburner for that, and the nearest neighbours are one field away.
We also have friends with a passivhaus which they commisioned and had specialist builders for. Roomy and cosy. Complex and I think expensive however.
If I was in the position to build another house, I’d certainly look at MVHR with blown air heating rather than an ASHP and wet system as would prefer a more constant temperature throughout the house and manage humidity better. With a portal roof / no attic there’s no room to retro-fit. Our house is ‘non-standard’ construction being steel portal, timber frame, wooden cladding and metal roof. We’re relatively exposed and survived a number of 90mph+ storms without incident. Currently waiting for a quote for solar panels plus battery- my heating guy reckons it’ll save about £1500/year which is my entire leccy bill.
It's pretty rare even in PassiveHaus certified buildings to be able to rely on MVHR for heating
https://www.earthwiseconstruction.co.uk/service/heating-cooling-with-mvhr/post-heating-with-mvhr/?
For a constant temperature throughout the house I don't think you can beat wet UFH run at a very low temperature (weather compensated, but only a few degrees above target). But it's a lot 'gubbins' to install. I'm thinking, with the increase in extreme heat, Air-Air heat pump is going to be the best future solution as with some solar panels you can have guilt free (and bill free) air conditioning when you need it.
Some friends of ours have a passive house but it's small and open plan but they manage with a single unit. What I don't know is how warm all the rooms are in winter. What I still don't understand about our own house is that our bedroom is reliably the warmest room in the house, despite having the underfloor heating turned off.
It's great for an efficient constant temp, but no good for quick heat in the evening. We have a logburner for that, and the nearest neighbours are one field away.
I’ve a very dim view of log burners. No matter how close you are to other homes, the emissions are bad, and in house emissions really bad for your health
why do you need a heat boost if you’ve got a comfortable constant temp? We just put on slightly more clothing when we’re sitting doing nothing. our friends who’ve now got the single a-a unit only recently installed it. Before that they had a couple of plug in radiators. If you need that little heat you’ve got thousands of saved up front costs to cover electricity costs.
I finally caught up with this last night.
Interesting I thought.
As has been said. So so expensive to retro fit, did they say how much it cost in the end on that house they did apart from £1000s?
Also they said that effectiveness of the heat source pump and external insulation is down to how it's installed and the time it took them to do it right.
In the real world, would they take that time.... No is my guess.
Anyway I enjoyed the programme.
I'll keep on with my logburner for now though 😁
