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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

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    • CommentAuthorborpin
    • CommentTimeDec 15th 2021 edited
     
    Hi Folks,

    Has anyone fitted a Zehnder MHRV unit? How long ago? Are you happy?

    They only offer 2 years guarantee for a unit costing £4K which is a bit miserly and suggests they do not have great confidence in it's longevity.

    Having to replace my Helios unit after 8 years (one motor went, other on the way out, summer bypass has failed) which is not great :cry:. Depreciation of £500 Per year. It would have been cheaper to fit trickle vents and waste energy.

    These units are all just a rip off as far as I can see.
    •  
      CommentAuthordjh
    • CommentTimeDec 15th 2021 edited
     
    My shortlist came down to a Zehnder or a Brink. I chose the Brink and am happy with it. FWIW, there's an interesting comparison thread at https://forum.buildhub.org.uk/topic/20283-zehnder-comfoair-q450-vs-brink-flair-400/

    Ours has been in six years (well 6½ now) and we haven't had any problems, but that's just a sample of one.
    • CommentAuthorborpin
    • CommentTimeDec 15th 2021
     
    @djh Does the Brink have anyway to access the unit for a Home Automation system? I can get a LAN module for the Zehnder that would give me all the data and control the unit from Home Assistant.
    •  
      CommentAuthordjh
    • CommentTimeDec 16th 2021
     
    Mine doesn't. I don't know about the capabilities of the current units.
  1.  
    Borpin, what advantages do you see with a £4k MHRV compared to a £1.5k MHRV for your replacement unit? You presumably don't need performance certificates or system design services, as you might with a new-build?

    Completely agree that the UK prices for MHRV are indefensible, compared to other appliances and to other countries. Presumably they only get away with charging that much because enough punters are willing to pay!
    • CommentAuthorborpin
    • CommentTimeDec 17th 2021
     
    Posted By: WillInAberdeenBorpin, what advantages do you see with a £4k MHRV compared to a £1.5k MHRV for your replacement unit?
    Which £1.5K unit do you suggest?
    •  
      CommentAuthordjh
    • CommentTimeDec 17th 2021
     
    Come to that which of the units have a £4K price tag?
  2.  
    Borpin's OP question is about a £4k Zehnder unit. The market leader in UK seems to be Vent Axia Kinetic range at around £1.5k. I have no experience with either, I'm curious to know what extra features you get if you go up market, sounds like Borpin has some hard earned experience!

    Eg I see on the web VA sentinel kinetic BH, 90% efficient, incl humidity sensor, 280m³/h, 0.59W/l/s, bypass, G4 filters, 5y warranty, wireless 'enable kit', £1492 incl VAT. Is that any good- I have no experience?

    My application is different (retrofit) as it is difficult to install a ducting network for a whole-house unit, so I am looking at using several single-room and two-room units at £300 each distributed round the house. Have fitted one unit so far, it seems effective but is a little noisy and has no summer bypass (we like open windows in summer).
    •  
      CommentAuthordjh
    • CommentTimeDec 18th 2021
     
    Posted By: WillInAberdeenBorpin's OP question is about a £4k Zehnder unit.
    Thanks, so my question is to Borpin?
  3.  
    WIA I'm looking to install one to my mid terrace but never got round to it so also interested.

    I was just thinking of extracting from kitchen and bathroom and putting the fresh air into the landing.

    I'd have to vent out to roof slate though I think
    •  
      CommentAuthordjh
    • CommentTimeDec 18th 2021
     
    Posted By: WillInAberdeenMy application is different (retrofit) as it is difficult to install a ducting network for a whole-house unit, so I am looking at using several single-room and two-room units at £300 each distributed round the house.

    If you use multiple units, how do you avoid the problem of through drafts caused by openings on multiple sides of the house?
    • CommentAuthorMike1
    • CommentTimeDec 18th 2021 edited
     
    Before going elsewhere, I'd check that you can't get the Zehnder unit at a better price as an import.

    I've been looking ahead to buying a Zehnder for my renovation in France and have seen prices for the same kit (though model numbers vary according to local markets) varying from under €2,000 to around €3,500. A willingness to search the web in Dutch or Polish could be handy.
    •  
      CommentAuthordjh
    • CommentTimeDec 18th 2021
     
    Posted By: Mike1I'd check that you can't get the Zehnder unit at a better price as an import
    What are import duties on things like MVHR nowadays? Or are they duty free?
  4.  
    VE, these old houses are unfortunately well 'ventilated' through gaps and cracks. No point just adding more ventilation, until all the cracks have been filled well enough that you are regularly needing to open windows/slots to control humidity!

    We have a typical arrangement of living rooms at the front of the house, bedrooms upstairs, and a 20th-C extension at the rear with kitchen, utility, bathroom, cloakroom in it. Loose plan is a single-room-MHRV wall mounted in the utility which is open to the kitchen; a two-room unit upstairs extracting from bathroom and feeding the main bedroom with vents through the roof; possibly a single-room unit in the downstairs loo and a two-room unit under the stairs feeding the lounge, ducts under the floor.

    DJH, all wet rooms are on the rear elevation so all vents on that side.
    •  
      CommentAuthordjh
    • CommentTimeDec 18th 2021
     
    Posted By: WillInAberdeenDJH, all wet rooms are on the rear elevation so all vents on that side.
    Ah, that's good to hear. Lucky configuration :) Design for sunlight means our living rooms and most bedrooms have southern exposure and so wetrooms have northern exposure except the main bathroom just has a west-facing exterior wall so I'm glad we've got a central MVHR.
    • CommentAuthorMike1
    • CommentTimeDec 19th 2021
     
    Posted By: djhWhat are import duties on things like MVHR nowadays? Or are they duty free?
    A good question. I suspect they'd come through without problem at the moment as full import controls aren't yet in place - but that will change, and the suppler may have reservations about exporting to the UK. Worth asking though, if the price saving is significant.
    • CommentAuthorJohn Walsh
    • CommentTimeDec 19th 2021
     
    FWIW, or a comparison, we installed a Vent-Axia Sentinel Kinetic 438222A 4 years ago. Intake is from a solar gain space in the winter and from a porch in the summer - i.e. there's no consideration of balancing intake and out re air pressure and therefore minimising fan load. It's controlled by a raspberry pi (well, 3 different speeds) and brings in solar warmed air on boost in the shoulder months (when temp sensors say we can do that) and cool air in the summer when needed. In short, it does a lot of work, cost around 1k and is so far, touch wood, doing fine. One thing that might help is that 'out' isn't vertical through the roof and is instead horizontal (with a slight slope to a wall outlet) so there's no water/condensation ever in the unit.
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