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Vent axia sentinel kinetic issue

  • 20-12-2024 01:36AM
    #1
    kevinc565
    Registered Users, Registered Users 2 Posts: 105 ✭✭


    I’ve recently had one of the fans replaced in my vent axia. After this I’ve noticed that the CO2 in the rooms is much higher than before.

    I’ve put a CO2 meter in the supply vents and the CO2 is very high indicating that the stale and fresh air are mixing in the unit. I’ve checked the inlet and air is fine so no issues on that side. Issue must be within the unit.

    When the front cover is off stale air gets sucked into the unit and into the rooms so mixing can occur in that scenario. I’m wondering if the rubber seals are worn could air mix when the front cover is on? Or if the heat exchangers isn’t exactly in the middle of the unit stale air could make its way around the sponges and into the supply .


    Anyone seen this happen or have any ideas?

    Post edited by kevinc565 on


Comments

  • #2
    Paul Kiernan
    Registered Users, Registered Users 2 Posts: 2,236 ✭✭✭Paul Kiernan


    https://www.boards.ie/discussion/2058385107/vent-axia-sentinel-kinetic-issue

    Bizarre. They're very simple devices! Any possibility the new fan is either inserted backwards or wired backwards so it's trying to draw the air the wrong way?



  • #3
    kevinc565
    Registered Users, Registered Users 2 Posts: 105 ✭✭kevinc565


    I don’t think so as that would result in suction from all the rooms and I’m definitely getting supply. I wonder could the heat exchanger be damaged?



  • #4
    graememk
    Moderators, Home & Garden Moderators Posts: 7,074 Mod ✭✭✭✭graememk


    https://www.boards.ie/discussion/comment/122977378#Comment_122977378

    There shouldn't be any mixing of air in a heat exchanger, warm air going out, gets cooled while the cold air coming in gets heated.

    Maybe the pipes got mixed up in re assembly?



  • #5
    kevinc565
    Registered Users, Registered Users 2 Posts: 105 ✭✭kevinc565


    Air isn’t supposed to mix but evidence is that it is mixing. Pipes are fine and connected in the correct place.

    i removed the heat exchanger and there’s no obvious damage. Hair dryer test (not accurate I know) shows air goes in and out the right way. I wonder could the seals inside the unit be the problem?



  • #6
    kevinc565
    Registered Users, Registered Users 2 Posts: 105 ✭✭kevinc565


    has anyone else tested this? Put a co2 meter inside the supply vents?



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  • #7
    graememk
    Moderators, Home & Garden Moderators Posts: 7,074 Mod ✭✭✭✭graememk


    https://www.boards.ie/discussion/comment/122978097#Comment_122978097

    What co2 meter were you using.

    I've briefly looked into getting them and found some are just "inferred" from other readings and can be quite inaccurate.



  • #8
    kevinc565
    Registered Users, Registered Users 2 Posts: 105 ✭✭kevinc565


    I’ve Netamo meters in rooms and a cheap Chinese meter in the vent. All give similar readings under similar conditions within their stated tolerances. They’re definitely accurate from a low, medium , high CO2 level perspective.

    I’d say most meters are calibrated to give a reading of 400ppm outside whereas actually background levels ar probably a little higher eg 422.



  • #9
    kevinc565
    Registered Users, Registered Users 2 Posts: 105 ✭✭kevinc565


    I think I’ve found the problem. When examining the unit and turning it on and off while doing so I noticed the supply pipe gets crumpled when the unit gets switched on due to the negative pressure.


    This restricts airflow into the unit. The outlet fan still demands air and as it can’t get this through the heat exchanger as the inlet is restricted it must pull stale air across the seals and spongers, effectively mixing the air and pumping that mixed air into the rooms.

    The outlet and inlet pipes were once switched during a service over 12 months ago, to reduce the length of pipe in the supply, but I’ve now switched them back.


    This fixes the problem as the ‘new’ supply pipe is more sturdy and doesn’t partially collapse under the negative pressure generated by the inlet fan.

    Perhaps the original installers used a more sturdy flexible pipe on the inlet side for this reason.

    This shows to me that the unit can mix air depending on the conditions. And without CO2 meters you’d never know.

    Not sure why the recent motor change exacerbated this. Perhaps a stronger motor or perhaps the inlet pipe affected during the installation.



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