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MHRV Noise Levels in New Build

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  • 22-03-2021 3:26pm
    #1
    Registered Users Posts: 14


    Hi, looking for some advice/info on MHRV noise levels for new build.
    Just moved in to new build, MHRV just commissioned last week. Straight away we are not happy with the noise levels from the room supply and extract inlets. The issue is in every room but particularly annoying in bedrooms and office. The noise is a loud humming and whistling sound. I downloaded a noise measuring app on my phone (I know this is not going to be 100% accurate) and it reads around 40db in the rooms just from the ducts alone (all other noise stopped before checking). I know that the building regs require a certain amount of air exchanges but they also stipulate that most rooms should be 30db or lower. The company that installed it are saying that theres nothing they can do thats just the noise level these systems produce. Would really love to know;
    - Has anyone had similar issue and seen an improvement?
    - Does anyone have a MHRV system recently installed that is barely audible, as I thought ours was going to be?
    - Any ideas on improving it?
    - Do we have any comeback with the installers if they have not met the noise levels set out in the regs? (They are almost completely paid.)
    The house is heated by heat pump, totally airtight, MHRV unit is installed in attic, ducting is full size (150mm) round ducting, solid plastic, joints look well sealed, its a 2400 sq foot fairly compact design in terms of layout, story and a half house.
    Thanks in advance :)


Comments

  • Registered Users Posts: 447 ✭✭ec_pc


    We have MHRV system in a 2750 SQ ft house since last year in conjunction with heat pump, air tightness etc.

    Before the system was installed, I had a specific conversation with the builder and the installer about noise / hum / vibrations etc. Installer was very professional and I felt really assured after that conversation. Main unit is installed upstairs in a small store room about 7 foot x 3. It's mounted close to the ceiling on a partition wall which backs onto a bedroom.

    I can honestly say our system is silent or as close as. It has 4 speeds and I have it set to run at 2 during the winter and 3 in summer. System automatically adjusts fan speed if required for short periods of times and then returns to default value. It certainly can't be heard during the day due to other background noise. At night when the house is quieter there may be a minor amount of noise from vents in the roof if system is running at top speed, but I would not say this is noisy.

    I have not measured the noise as it's not a concern but the manual indicates noise ranging from 29 db ( low speed) to 57 db (high speed). Firstly I would say check your manual but without doubt I would definitely approach the installer again or ask to see another installation they have done. What brand is your system?

    Perhaps it's just a case of getting used to your new environment and maybe you are just picking up easily on new sounds. For example we have an electric pump in the utility room for the water and I thought it was a little loud when we moved it. Plumber said it was standard in terms of noise and now we don't even notice it.


  • Registered Users Posts: 388 ✭✭Biker1


    HayDay18 wrote: »
    Hi, looking for some advice/info on MHRV noise levels for new build.
    Just moved in to new build, MHRV just commissioned last week. Straight away we are not happy with the noise levels from the room supply and extract inlets. The issue is in every room but particularly annoying in bedrooms and office. The noise is a loud humming and whistling sound. I downloaded a noise measuring app on my phone (I know this is not going to be 100% accurate) and it reads around 40db in the rooms just from the ducts alone (all other noise stopped before checking). I know that the building regs require a certain amount of air exchanges but they also stipulate that most rooms should be 30db or lower. The company that installed it are saying that theres nothing they can do thats just the noise level these systems produce. Would really love to know;
    - Has anyone had similar issue and seen an improvement?
    - Does anyone have a MHRV system recently installed that is barely audible, as I thought ours was going to be?
    - Any ideas on improving it?
    - Do we have any comeback with the installers if they have not met the noise levels set out in the regs? (They are almost completely paid.)
    The house is heated by heat pump, totally airtight, MHRV unit is installed in attic, ducting is full size (150mm) round ducting, solid plastic, joints look well sealed, its a 2400 sq foot fairly compact design in terms of layout, story and a half house.
    Thanks in advance :)

    This is a common issue with a branch duct system that you seem to have. Sound attenuators in the duct work are generally required in this scenario.


  • Registered Users Posts: 12,409 ✭✭✭✭Calahonda52


    What make and model unit have you got?
    how is it mounted, stud or solid wall?

    What details are supplied in the BER?

    Ask to see the MHVR design.

    As well as sound attenuators, if the unit has been down sized, say from 350 m3/h to 200 m3/h, which is cheaper, and the house needs
    180/m3 h, then the 200 unit is working close to max, higher fan speed, so louder

    “I can’t pay my staff or mortgage with instagram likes”.



  • Registered Users Posts: 14 HayDay18


    Thank you Biker1, what do you mean by branch duct system, what other kind of systems are there? Do you think the installers should have known that attenuators were required?


  • Registered Users Posts: 14 HayDay18


    Thanks, The unit is a Vent-Axia Sentinel Kinetic Plus 220-240V 50Hz - does this model seem an appropriate size for a 2400 sq foot house? How can I find this out? It is running at 60% all the time, I think goes to 100% on boost mode. It is mounted on a wooden frame, in the attic but up off the floor. I have stood beside the machine itself and its fairly quiet and no noticeable vibration. The room grilles are what is producing annoying noise.


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  • Registered Users Posts: 12,409 ✭✭✭✭Calahonda52


    To see if its air speed, maybe crank it down from the 60% and see what happens to the noise

    “I can’t pay my staff or mortgage with instagram likes”.



  • Registered Users Posts: 388 ✭✭Biker1


    The other type is a plenium box system with individual ducts running from it to each room. And yes if they are competent persons they would have known how to design and install the system to be in compliance with Part F of the building regulations. Sadly this is often not the case.


  • Registered Users Posts: 8,974 ✭✭✭893bet


    HayDay18 wrote: »
    Thanks, The unit is a Vent-Axia Sentinel Kinetic Plus 220-240V 50Hz - does this model seem an appropriate size for a 2400 sq foot house? How can I find this out? It is running at 60% all the time, I think goes to 100% on boost mode. It is mounted on a wooden frame, in the attic but up off the floor. I have stood beside the machine itself and its fairly quiet and no noticeable vibration. The room grilles are what is producing annoying noise.

    60 percent sounds a lot.

    I have a ventaxia also and it runs at 35 percent (or 30) and kicks up to 60 when it detects the need after a shower or similar.


  • Registered Users Posts: 876 ✭✭✭keno-daytrader


    HayDay18 wrote: »
    Thanks, The unit is a Vent-Axia Sentinel Kinetic Plus 220-240V 50Hz - does this model seem an appropriate size for a 2400 sq foot house? How can I find this out? It is running at 60% all the time, I think goes to 100% on boost mode. It is mounted on a wooden frame, in the attic but up off the floor. I have stood beside the machine itself and its fairly quiet and no noticeable vibration. The room grilles are what is producing annoying noise.

    We have a Ventaxia Sentinel Advance, and its totally silent in all rooms even when on boost. Our boost is set to 65% and 22%/20% in normal mode. Sounds like a design issue, maybe fitter going cheap and not fitting silencers?

    However theres no way it should be running at 60% in normal mode for your size house.

    The Kinetic plus b is good for houses up to 260sqm so yours should be fine to run in that house.

    Did the fitter give you a commissioning cert, and are all extract and flow volumes listed per room?

    ☀️ 6.72kWp ⚡2.52kWp south, ⚡4.20kWp west



  • Registered Users Posts: 364 ✭✭Frogeye


    We have MHRV system. Don't hear anything in most rooms. Main unit is in the attic so when its boosted ( say when taking a shower) you can hear the motor pick up then drop off again after 12 mins or so. And that can only be heard only in the bed room underneath the unit. You don't hear anything in the other rooms.

    My main problem with noise is the water pump, goes like the clappers when is kicks on. I eventually got the plumber to put in some flexis and it improved but it still not great. I'm not sure if its the specific model or the just pump in general....


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  • Registered Users Posts: 12,409 ✭✭✭✭Calahonda52


    Biker1 wrote: »
    The other type is a plenium box system with individual ducts running from it to each room. And yes if they are competent persons they would have known how to design and install the system to be in compliance with Part F of the building regulations. Sadly this is often not the case.

    Do they not have to be signed off by a NSAI approved person?

    the site is down

    “I can’t pay my staff or mortgage with instagram likes”.



  • Registered Users Posts: 388 ✭✭Biker1


    Do they not have to be signed off by a NSAI approved person?

    the site is down

    Yes, if the house comes under the 2019 Part F regulations. If that is the case the owner can request the cert from the engineer or if one is not available he should get a registered validator to do the test. This would tell if the system was designed, installed and commissioned correctly.


  • Registered Users Posts: 1 homewardsbound


    Hiya @Biker1

    I have the same issue with the Vent Axia in a 360sqm house! Painful noise!

    Did you find any other noise reduction solution you can share? I have it set to run at 30% for bedtime and morning so it’s not bad then. But it runs at 60% the rest of the day, our house is 380sqm - and very annoying.



  • Registered Users Posts: 876 ✭✭✭keno-daytrader


    What model Vent Axia do you have? 60% running in background seems very excessive if the unit is big enough for your house.

    ☀️ 6.72kWp ⚡2.52kWp south, ⚡4.20kWp west



  • Registered Users Posts: 302 ✭✭lway


    Sorry to butt in but I have a similar issue with my MVHR system. The noise is really annoying. A Vent-Axia Sentinel Kinetic system as well, house is around 210 sq/m.

    The system was commissioned and put on Purge mode for an hour, fans running at 100%, then dropped down to what should have been "normal" operating at 40% fan speed but it was way too noisy, couldn't sleep at night kind of noisy. Called installer out and he reduced "normal" running speed to 24% and things improved. Still too noisy for the missus to sleep with so had to fit a plug timer to knock it off between 10:30pm and 7 in the morning.

    It's now noticeably noisier, running at 38% all the time with a symbol on the screen to show it's being boosted, presumably by the internal humidity sensor.

    Room temp set to 25deg on the system.

    @homewardsbound I'd say 60% fan speed is way too high, according to the manual "Normal" should be 40% but that's even too noisy for us.

    Is there a little infinity type symbol on the display showing it is being boosted ?



  • Registered Users Posts: 2,600 ✭✭✭Yellow_Fern


    Not a cheap solution, but I wonder is the ductwork sub par in some parts of the house? If there was less pressure drop at the furthest end of the house, maybe you could run the system at a lower speed? Another thing to look at is the relative humidity which it kicks off at. I have seen some set so low, they are triggered by rainy days even if a house is empty. With Vent Axia, you can change this in installer mode. Changing could have implications for mould so be cautious in changing it.



  • Registered Users Posts: 33,931 ✭✭✭✭listermint


    Room temp should not be at 25 degrees.

    Also you need to check what Vent Axia you have there are multiple sizes in the kinetic range from 230m³ up to over 600m³ . However these would be max speed ratings. For example the smallest model is not really suitable for your house at 210m³ it would be running at its extreme to deal with the building. You should have one of the medium models for a house that size.

    Did you go over the install plan, documentation and commissioning data sheets ?

    Every unit should be sized appropriately for the house and allow for periods when guests are around and the unit needs overhead to cope with the additional requirements.



  • Registered Users Posts: 1,191 ✭✭✭dmcdona


    We have a Renovent HRV. NZEB 200m2 house (A1 BER). It has four settings - but each setting can be programmed on the main unit.

    Setting 1 = 40m3/h (when we are not away)

    Setting 2 = 140m3/h (nearly a an entire house airchange per hour).

    Settings 3 and 4 are 200 and 300 m3/h (I think).

    We live in the country and with triple glazing, the house is "silent" - you really could here a pin drop. We only ever use setting 1 and 2. Both are not noticeable at all. We did use 3 during covid when we had workmen in - more noticeable but not annoying. More like "there's a different noise - what's that" - rather "what is that whistling/humming?" I can't recall using setting 4 except probably when we moved in and I was messing about with it.

    Also of note, the main unit is in a "plant room2 to the side of the house. Part of the house but only an external door (and insulated blockwork between it and the house).

    It sounds to me like you need someone to take a look...



  • Registered Users Posts: 14 HayDay18


    BER assessor was here recently and in one of the bedrooms he commented on the noise of it, had a look in the attic and he was adamant that the sharp bend in the ductwork immediately after leaving the unit was responsible for the noise. He said its pressure on the machine too which will cause it to burn out faster. He said a long bend in the ducting but I can't find many really long curved bends online. I have the machine at 35% during the day and 20% at night just so its less noisy at night. Does anyone agree with what he is saying?



  • Registered Users Posts: 12,409 ✭✭✭✭Calahonda52


    picture please

    also why just one room?

    could be that that room was not commission properly and has more airflow

    “I can’t pay my staff or mortgage with instagram likes”.



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