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Heat recovery unit, dummies guide?

  • 31-08-2019 5:52pm
    Registered Users Posts: 6,710 ✭✭✭ Grumpypants

    Can anyone give me a quick users guide to the air heat recovery unit. I bought a house 4 years ago and it came with a few bits pre installed ceiling vent heat recovery unit and solar tubes, but no instructions on how to use them.

    The unit is a Mitsubishi lossnay there is a big box in the attic, there are pipes running to every room and a small control panel in the utility. But it's a pretty simple control. It can either be on or off or set to heat exchange or bypass.

    It doesn't look to have any temperature or timer settings.

    So i'm wondering when do you actually use it? And is it just left in all the time?

    This time of year all the windows are open so it's off.


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

    It should be on 24/7 and keep the windows closed.

    The idea is that it pumps in fresh air all the time without loosing the valuable heat in the house. Opening windows defeats the purpose of having the unit.

    There should be filters in the main unit that should be cleaned and/or changed at least once or twice a year.

  • Registered Users Posts: 6,710 ✭✭✭ Grumpypants

    I gave the filters a look and one is pretty black. So I must order new ones. They defo haven't been changed in 5+ years.

    At this time of year the house is far too hot, it's 22 degrees today. So keeping heat in at this time is not a worry. The heating goes off from April to October bar a freak cold snap.

    It's more so for the winter I reckon.

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

    It has a summer bypass mode which means it lets the air straight in the same as opening the windows but it will filter the air so you’ll have less flies.

    As I said, it’s designed to be on 24/7.

  • Registered Users Posts: 6,710 ✭✭✭ Grumpypants

    Thanks for the replies. So pretty much seal up the house and let it run all the time.

    Will give it a go.

  • Registered Users Posts: 569 ✭✭✭ thos

    Do have a look and see if there is a control panel, or option to add one. I find the control panel on my Vent Axia pretty useful, and I've wired down into a more accessible area.

    The summer bypass usually might have temperate settings when it's active, I found it more useful to tweak these for 'our summer' settings as opposed to defaults or what other countries might consider summer.

    Mine also has a Boost and Purge, so where the fan usually sits at around 20%, it's useful to stick it too 100% if the house has gotten particularly warm or stuffy during a hot day. Some units would have timers to use in 'Evening' mode to help clear the house of hot air during a summers day.

    Also, try for filters, found them quick, easy and cheap.

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  • Registered Users Posts: 6,710 ✭✭✭ Grumpypants

    There is a controller alright but the inputs are pretty limited.

    By pass/heat exchange/auto
    Fan speed low/high

    Delayed start and filter seem to have no reaction.

  • Registered Users Posts: 160 ✭✭ al2009

    I think this is the manual for it;


    for some reason the full link wont load, search under lossnay or controls

    Before you change those filters, slide them out and hoover them, they are supposed to be black originally, they are absolutely mental money to buy the originals. The heat exchange cores also slide out, the original owner may not have used the unit much so filters and cores could be fine.