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MHRV Units: Options?

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  • Options
    #32
    galwaytt
    Registered Users Posts: 12,776 ✭✭✭✭galwaytt


    runawaybishop wrote: »
    Not sure why you think that is easier? There are less meters of ductwork the other way so you only have the clean the central direct run and then come up from the exit/entry in each room, rather than having to clean back to source with a manifold.

    Exactly. 5 times the pipework, in small size, does not make for easier anything.

    See pics of a manifold system at first fix attached.........

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



  • Options
    #33
    runawaybishop
    Registered Users Posts: 9,504 ✭✭✭runawaybishop


    romeonovember wrote: »
    he was going to spec the zehnder 550 comfoair for our house. from looking at the zehnder website, the 350 should do it.

    Your house is about 270 meters squared and i am assuming 2.4 meters height per floor, so you are looking at ~650 meters cubed. You need to shift 1/3rd of this volume per hour to meet standards so thats 216 meters cubed. That 350 unit can shift 218 CFM, or roughly 6 meters a minute - as you need only 3.6 (216/60) the 350 model looks like it has plenty of head room - you want to make sure it doesn't have to run at capacity as that costs more and is noisier.

    The unit i used is this one as when i did my research it had the best performance/features for the money - just so you have a reference for the cost/performance.

    Did they show you any calcs as to why you'd need the 550 model? It looks like it is overspecced but would definitely be able to run away at minimum settings and therefore be very quiet and cheap to run.


  • Options
    #34
    Curious Geroge
    Registered Users Posts: 1,014 ✭✭✭Curious Geroge


    runawaybishop wrote: »
    Your house is about 270 meters squared and i am assuming 2.4 meters height per floor, so you are looking at ~650 meters cubed. You need to shift 1/3rd of this volume per hour to meet standards so thats 216 meters cubed. That 350 unit can shift 218 CFM, or roughly 6 meters a minute - as you need only 3.6 (216/60) the 350 model looks like it has plenty of head room - you want to make sure it doesn't have to run at capacity as that costs more and is noisier.

    The unit i used is this one as when i did my research it had the best performance/features for the money - just so you have a reference for the cost/performance.

    Did they show you any calcs as to why you'd need the 550 model? It looks like it is overspecced but would definitely be able to run away at minimum settings and therefore be very quiet and cheap to run.

    Breakdown looks odd, 350 unit is spec'ed for ~290m3/h which is 4.8 per min which is still good enough but are these correct. The 290 comes from wolfgang cert but website would say that the unit is good for 400m3/h. (I'm only learning this stuff myself)


  • Options
    #35
    MicktheMan
    Registered Users Posts: 2,837 ✭✭✭MicktheMan


    runawaybishop wrote: »
    Not sure why you think that is easier? There are less meters of ductwork the other way so you only have the clean the central direct run and then come up from the exit/entry in each room, rather than having to clean back to source with a manifold.

    Well, some of the "installations" I have seen which have a main central duct run (150 to 100 to 150mm in order to get past opstacles/ mixture of solid / flexible), branches to plenums, and then more branches to rooms (all built in and inaccessible of course) cannot be properly cleaned without major disruption. At least with the manifold and individual runs to each room, each run can be swept with a type of brush / rod system and you are sure that the entire duct has been cleaned.


  • Options
    #36
    runawaybishop
    Registered Users Posts: 9,504 ✭✭✭runawaybishop


    Curious Geroge wrote: »
    Breakdown looks odd, 350 unit is spec'ed for ~290m3/h which is 4.8 per min which is still good enough but are these correct. The 290 comes from wolfgang cert but website would say that the unit is good for 400m3/h. (I'm only learning this stuff myself)

    Docs always state higher than the reality, with runs that aren't straight etc


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  • Options
    #37
    runawaybishop
    Registered Users Posts: 9,504 ✭✭✭runawaybishop


    MicktheMan wrote: »
    Well, some of the "installations" I have seen which have a main central duct run (150 to 100 to 150mm in order to get past opstacles/ mixture of solid / flexible), branches to plenums, and then more branches to rooms (all built in and inaccessible of course) cannot be properly cleaned without major disruption. At least with the manifold and individual runs to each room, each run can be swept with a type of brush / rod system and you are sure that the entire duct has been cleaned.

    Thats true, it would very much depends on the ducting run itself - you are supposed to avoid right angles but i wouldn't put any money down that there aren't a good few installations that are less than proper :)

    Not sure if you'd manage to rod all those runs though as you cant break up the length - at least with a central run you can clean that and then work back from the inlet/outlets.


  • Options
    #38
    romeonovember
    Registered Users Posts: 12 ✭romeonovember


    well I better get them to do the proper calculations before I proceed any further. I have spoken to a-snip- installer in Ireland and he is telling me that the ROI distributer is ripping off the price for the unit and accessories, and from speaking to the UK suppliers on their prices this would seem to be true.


  • Options
    #39
    galwaytt
    Registered Users Posts: 12,776 ✭✭✭✭galwaytt


    MicktheMan wrote: »
    Well, some of the "installations" I have seen which have a main central duct run (150 to 100 to 150mm in order to get past opstacles/ mixture of solid / flexible), branches to plenums, and then more branches to rooms (all built in and inaccessible of course) cannot be properly cleaned without major disruption. At least with the manifold and individual runs to each room, each run can be swept with a type of brush / rod system and you are sure that the entire duct has been cleaned.

    ...I would really like to see anyone rod/brush that 75mm corrugated pipe I've come across...........I can't see it happening without damage tbh.

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



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