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Decentralised MVHR


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I'm considering retrofitting a decentralised MVHR system to a three-floor concrete built house with no loft (nowhere obvious to put a central unit, and I can't think how to run the ducting except on wall surfaces...) A search of the forum brings up Blauberg, which is the system I've been looking at with a WiFi connection between units, but nothing definitive. Has anyone used them or have any views on the technology generally? I can't imagine they're as effective / efficient as a centralised unit . The house seems pretty airtight with no trickle vents on any of the windows so I'd like to get some proper ventilation going, although mould has so far appeared only in one stairwell to the roof.

 

Thanks!

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I reviewed this option for a new build and decided against it vs fully ducted system. That said, I think In your Situation for retro fit they could be your best solution all things considered. I also looked at another brand called PRANA decentralised MVHR units. 

I favoured these when compared with Blauberg, but only via my desktop study and didn’t test or use either so you’ll need to do your research. Both companies priced my project and I was keen to make this work and avoid all the ducting and potential noises of a traditional ducted system but it turned out that for them to work effectively for a whole house virtually one in every room is required and large rooms like kitchen and lounge there were two. So costs very going against this option for my new build. 

 

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On 08/03/2020 at 10:21, MrSniff said:

nowhere obvious to put a central unit

There are low-profile ceiling hung units (e.g. Brink Renovent Sky 200, Nuair MRXBOXAB-ECO-LP2) and units with dimensions to match kitchen wall cupboards (Vortice Vort HR 200 BP, Nuaire MRXBOX95AB-WM1, Zehnder ComfoAir 180) that might work, subject to your air flow requirements (which might be too high for a single unit, if you have a 3-floor house). Zehnder's ComfoPipe Plus twin duct range is also designed to fit along the top a row of kitchen wall units before connecting to their 70mm high flat distribution ducting.

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I looked at fitting some Dutch through the wall individual room MVHR units.  They seemed pretty impressive, very quiet and with decent performance.  The snag I ran into was that they would have ended up being extremely expensive, as to meet building regs I would have had to fit loads of them, even though the manufacturer made it clear that we'd only need two, or possibly three, for our size of house.

 

This probably isn't an issue when retrofitting MVHR to an existing house, though.

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  • 3 months later...

I'm after the same, although from different perspectives: refurbishment and extension limitations as well as operation.

As for the latter, I don't like consequences of centralized system:

- when one bathroom needs boost, all have it - so it gets 1/3 of total flow (we have 3 bathrooms) , whereas it could have been 80%+, if the flow in other could be kept unchanged - resulting in shorter purge time.

- with typical layout (living room + kitchen downstairs, bedrooms upstairs) either of the floors is being served pretty much half of total time only (downstairs-day, upstairs-night), so it would do with 'trickle' when not occupied

As for the former, it is tough to retrofit ducting, if building wasn't designed with them in mind - having more localized 'zones' can be a lifesaver. With possible added bonus of no need for balancing.

But I'm struggling to find hardware that could do the job :(

For the planned kitchen/diner extension I need something small, as I won't be able to connect the existing building to it (maybe at a stretch I could punch through the wall and include living room).

The solutions I'm considering at the moment are:

https://www.vent-axia.com/range/hr100rrs price ~ £250,  flow up to 18 l/s, efficiency up to 70%

https://www.blauberg.co.uk/en/blauberg-komfort-ultra-d105-a-single-room-heat-recovery-unit price ~£300 , flow up to 29 l/s, efficiency up to 72%

http://www.fansandspares.co.uk/assets/shop/datasheets/1389189023_VTC_LOW_E(1)_UNIT.pdf price £650, flow up to 45 l/s, efficiency up to 95%

https://www.nuaire.co.uk/residential/heat-recovery-mvhr/mrxbox95ab-wm1 price ~£720 , flow up to 35 l/s, efficiency up to 85%

 

Considering that it will serve kitchen/diner, so will boost only occasionally when cooking, should I be concerned about efficiency?

Or - thinking about refurb and refitting in the main building (80 sqm, last 2 devices could do that) - should effciency be high on my list, or treat it rather as a bonus?

 

 

 

 

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  • 2 weeks later...

Well I've got completion day set now, so I know when I'll be able to check what my options (joists directions, wall drilling etc) really are.

I think that will be a dealbreaker: considering (as it stands now) I'd need 2 units, if laying ducts will not be that tough after all, then total cost may match 1 decent device with its ducting.

I would still like to have better control on delivery to non-occupied rooms and bathrooms boost, I've been looking at different duct dampers, with iris ones (like http://www.ajs-vent.co.uk/files/Iris Damper Range - Full Speciication.pdf) looking promising, especially motorized version. Anybody having experience with those?

As for the efficiency I learnt a bit here https://www.paulheatrecovery.co.uk/products/methods-of-calculating-the-heat-recovery-efficiency/ - but I'm not totally shocked

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  • 5 months later...
On 09/03/2020 at 17:22, Jeremy Harris said:

I looked at fitting some Dutch through the wall individual room MVHR units.  They seemed pretty impressive, very quiet and with decent performance.  The snag I ran into was that they would have ended up being extremely expensive, as to meet building regs I would have had to fit loads of them, even though the manufacturer made it clear that we'd only need two, or possibly three, for our size of house.

 

This probably isn't an issue when retrofitting MVHR to an existing house, though.

Who was the manufacturer of these units?

 

Thanks

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  • 1 year later...

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