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Mhrv questions

  • 03-02-2021 5:29pm
    #1
    Registered Users Posts: 17 Davy87


    Only at the planning stage of house, house will be around 2500 sq foot. Should the MHRV unit be inside the house, as in not the attic due to the attic being colder? If this is the case should only the ducting in the attic be insulated ? Is there a duct that's better than another type of duct? The ducts say in the kitchen have a filter at ceiling to prevent grease / dust build up in pipes ?
    Thank you if anyone can answer these questions


Comments

  • Registered Users Posts: 2,544 ✭✭✭ MicktheMan


    Ventilation unit and all ducting to be within the thermal envelope should be the goal if building from scratch. Anything else is a missed opportunity, imo. Also, having the unit itself inside and easily accessed will help with it being maintained on a regular basis (filter cleaning / replacement)

    Any part of the system outside the thermal envelope should be insulated.

    Cleaning / maintenance of ducting should be a primary factor when deciding on duct type / layout as well as access to plenum boxes etc.


  • Registered Users Posts: 11,213 ✭✭✭✭ KCross


    MicktheMan wrote: »
    Ventilation unit and all ducting to be within the thermal envelope should be the goal if building from scratch.
    Anything else is a missed opportunity, imo.

    Absolutely that for a new build. Madness not to.
    MicktheMan wrote: »
    Also, having the unit itself inside and easily accessed will help with it being maintained on a regular basis (filter cleaning / replacement)

    And +1 on that also.
    I remember when looking at these for my own build I went to another house to see it in operation and it was in an attic and difficult to get to. That means he was up a ladder and on his hand/knees to get the filter replaced a few times a year. I said no to that in my own mind and put it in an accessible location. It's fine when you are fit and healthy... what about when the body starts giving out and doesnt want to be up/down ladders or crawling attic spaces! ;)

    For a new one-off build you should have a "plant room". Get all your heat recovery, plumbing, electrical consumer unit, heat pump, internet, data cables etc all terminated there. Its taking space out of your build but it makes life easier in the long term.


  • Registered Users Posts: 17 Davy87


    For a 2500 sq foot, 2 story house, what would be a good size plant room? Is there a filter on the stale air pipe in the room to catch dust? Does the ducts ever need to be blew /cleaned out?


  • Registered Users Posts: 11,213 ✭✭✭✭ KCross


    Davy87 wrote: »
    For a 2500 sq foot, 2 story house, what would be a good size plant room?

    There isnt a set size.
    It depends on what you plan to put into it. e.g. will you have a heat pump? They tend to be relatively large and have a water tank attached/integrated to them also.

    And its not so much the size of the room but the amount of wall space as you wont have loads of free standing items.
    e.g. Heat pump, plumbing, consumer unit etc are all wall mounted so a long narrow room is better than a big open space room but its all dependent on the house design really.


    Do you have an architect designing the house? He should be able to design it in based on the remit you've given him for things like MHRV and Heat pumps etc.


  • Registered Users Posts: 10,927 ✭✭✭✭ Calahonda52


    All as above and you need a designer for the unit.
    larger unit, larger ducts larger supply and extract grilles all lead to a quieter experience
    https://www.zehnder.co.uk/mvhrnoiseadvice
    If the unit in in the cold space, research has shown a drop in efficiency of c 20%
    At design stage you could nearly design the house around the optimal layout for the ducting :)


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  • Registered Users Posts: 275 ✭✭ macgabhs


    100% agree. I wish I had considered this more for my build. MHRV and comms cabinet are in the attic. I have a stira and floor boards above the insulation but it’s going to be a pain in the future. Ducts are insulated in the attic. I did rig up a temp sensor on each duct coming/going to the MHRV unit before to look at efficiency. Once external temp dropped into single figures efficiency dropped quickly. Still better than an open window though.


  • Registered Users Posts: 17 Davy87


    Is there a company in the north west I could send plans to get his advice on or change to suit the system ?


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