Location of MVHR System (Zehnder Q350)

[revelation]

Hi all

 

I was wondering if someone could offer a little insight.  We are having our heat recover system installed soon, we have the decision to make whether to install it in our downstairs utility room, or our loft (has been converted and is fully insulated with easy access).  The utility room would be our preference as we have space and it allows for a larger bathroom in the loft, and will make external venting (supply and extract) easier.

 

 However, I biggest concern is the noise.  The utility room is next to our open plan kitchen and our living room too, we plan to use Zehnder comfowall attenuators and manifold so that should help too.

 

Does anyone have much experience with such a set up that could offer some advice?

 

Regards

[jack]

It depends on how loud the unit is.

 

Our Brink Excellent 400 is in our pantry, which is off the kitchen and doesn't have a door. It's boxed in with simple kitchen-type doors without any attempt at sealing or otherwise soundproofing them against noise.

 

You can't hear the unit at all when it's on low (about 25% power). You can hear it on boost, but since I only manually use that now and again, it's actually helpful being able to hear that it's still on so I remember to turn it off! It isn't an offensive or intrusive noise - just a low level background roar.

[mvincentd]

My q350 is mounted to concrete wall in utility room, 4 metres as crow flies from where i'd sit on sofa.  I've concrete floors throughout too so sounds do travel in the house.

Sitting on the sofa in the dead of night with mvhr on 197m3/h 50% fan speed the DecibelX iPhone app' measures 29....i hear the mvhr but not from the unit directly but from the 3 outlets that feed the living/dining area.  Turning the mvhr up or off makes an audible difference but doesn't shift the decibel reading.  Nowhere in the house reads lower than 28.4 on the app'.  Standing in the utility room 1 metre from the unit it reads 32.5 and nobody could fail to notice it on entry.

 

I dont think my install is the quietest....the supply and return ducting directly out of the unit could have been done better (i did it!).  The utility room isn't quiet..i wouldn't want to sleep in there.....it would be like a hotel room with an aircon unit running, which i hate.  I do sleep in the living room (when i get in trouble) and am aware of the mvhr, but it doesn't bother me...the fridge will kick in soon enough with some weird noise anyway that totally overshadows the mvhr!

 

I wouldn't let noise concerns prevent you from siting it in your utility.  If you are hypersensitive to noise then you could potentially tune into air pushing out of bedroom outlets anyway (depending on how your system needs setting up). 

 

 

[Alexphd1]

We have installed silencers in the flow duct between the mvhr unit and the manifold. Don't know how effective they are but if noise was a issue later down the line and we didn't have the silencers installed i would be severely kicking myself!

[revelation]

Thats handy to know.  We will be using the Zehnder silencer/attenuated manifolds which go directly on the main unit.  Our sitting space will be pretty close to the utility room, (around 2-3 metres away from the unit).

 

I guess due to the airflow you will have some low level sound all of the time anyway, which I expect.  

 

Would anyone recommend going for a Q450 instead of the Q350.  my house is pretty much 165m sq which is the upper limit of the Q350, so I assume the Q450 would run at a lower level to do the same work?

 

Regards

[mvincentd]

10 hours ago, revelation said:

my house is pretty much 165m sq which is the upper limit of the Q350,

I'm 200sqm, the attached screenshots from the app show currently it's shifting 194cubic m by using 50% fan duty.

My commissioning cert' says medium supply-54.6%, high supply-72.2%

I'd assume like you re' the q450 though so if space and money is no issue.....but i don' think you NEED it.

[revelation]

On 15/12/2020 at 23:26, mvincentd said:

I'm 200sqm, the attached screenshots from the app show currently it's shifting 194cubic m by using 50% fan duty.

My commissioning cert' says medium supply-54.6%, high supply-72.2%

I'd assume like you re' the q450 though so if space and money is no issue.....but i don' think you NEED it.

 

 

If you're running a Q350 for 200sq.m and its running well, then that is certainly reassuring that I should be good with running it on mine.  Especially as I have the opportunity to purchase a Q350 unit for less than 1500 and a Q450 would cost me more than 2000.  Did you go for a pre-heater?

 

Regards

 

[mvincentd]

7 hours ago, revelation said:

Did you go for a pre-heater?

No, I think I took the stance of not getting drawn into all the 'marginal gains' add-ons....i'm happy enough if it does it's core function well.  

[andy]

Another vote here for the Q350, I've got that unit mounted in our loft on a timber stud wall that's above bedroom/bathroom and there's zero noise downstairs from the unit, no transmission of vibration (there is no vibration!) and we just did a standard wall mounted install.  The only noise you're likely to hear is the airflow from the vents itself so make sure you get the system designed with correct attenuators.  All my rooms are about 25dB or less and you can just about hear the supply/extract flows; we have Lindab spiral steel ducting and fittings.

 

Having never lived with MVHR before, we are absolutely amazed by it -  especailly how effective it is at drying towels, washing, etc.  Also it is really good at sensing humidity increases (e.g. boil a pan in the kitchen) and increases the extract rate automatically.  We have yet to need to touch the unit to do anything other than pop to the loft and admire it occasionally

 

Make sure you get the LAN connect module for it as you get the app for viewing status, etc.

[djcdan]

On 20/12/2020 at 00:38, revelation said:

 

 

Especially as I have the opportunity to purchase a Q350 unit for less than 1500

 

 

@revelation where have you found the Q350 for less than £1500? 

[revelation]

6 hours ago, andy said:

Another vote here for the Q350, I've got that unit mounted in our loft on a timber stud wall that's above bedroom/bathroom and there's zero noise downstairs from the unit, no transmission of vibration (there is no vibration!) and we just did a standard wall mounted install.  The only noise you're likely to hear is the airflow from the vents itself so make sure you get the system designed with correct attenuators.  All my rooms are about 25dB or less and you can just about hear the supply/extract flows; we have Lindab spiral steel ducting and fittings.

 

Having never lived with MVHR before, we are absolutely amazed by it -  especailly how effective it is at drying towels, washing, etc.  Also it is really good at sensing humidity increases (e.g. boil a pan in the kitchen) and increases the extract rate automatically.  We have yet to need to touch the unit to do anything other than pop to the loft and admire it occasionally

 

Make sure you get the LAN connect module for it as you get the app for viewing status, etc.

 

Thank you for the information, how many sq. m is your property?   Because ours is largely a retro-fit  we don't have the facility to go for anything more than 75mm radial ducting, so I expect that we will be getting more noise than the ducting you used.  However we are using Zehnder Comfo Attenuated Manifolds and due to having UFH on all floors most of the spaces between floors will have acoustic rock wool between them.  So I am hoping it wont be too loud.

 

How has it helped drying towels and washing? Just by detecting the moisture levels and boosting extraction?

 

Regards

[andy]

4 hours ago, revelation said:

 

Thank you for the information, how many sq. m is your property?   Because ours is largely a retro-fit  we don't have the facility to go for anything more than 75mm radial ducting, so I expect that we will be getting more noise than the ducting you used.  However we are using Zehnder Comfo Attenuated Manifolds and due to having UFH on all floors most of the spaces between floors will have acoustic rock wool between them.  So I am hoping it wont be too loud.

 

How has it helped drying towels and washing? Just by detecting the moisture levels and boosting extraction?

 

Regards

 

Regarding the drying, it's the continual movement of air combined with UFH, so you get a nice flow of warmed air over the drying racks and if the humidity increases enough, it will increase the extract level to clear it.  We've realised we don't need to use the tumble dryer anything like as often, which is great.

 

My house is about 180sqm and we've mostly got 100mm ducting so as you say, we're likely to have quieter movement of air in general due to that.

[tanneja]

On 28/12/2020 at 08:43, djcdan said:

 

@revelation where have you found the Q350 for less than £1500? 

@djcdan yes, can you share this please?

[tanneja]

On 15/12/2020 at 23:26, mvincentd said:

I'm 200sqm, the attached screenshots from the app show currently it's shifting 194cubic m by using 50% fan duty.

My commissioning cert' says medium supply-54.6%, high supply-72.2%

I'd assume like you re' the q450 though so if space and money is no issue.....but i don' think you NEED it.

 

 

 

Similar to @mvincentd, our house is around 200m2 (500m3). 

 

UK Building Regs seem to say (whether applying the whole house 0.3 l/s/m2, or constant extract rates) we need 55l/s or 200m3/hr or 0.4 ACH.  I arrive at approximately the same 200m3/hr number when applying an ACH approach on the room volumes through using 0.5 ACH for bedrooms and habitable downstairs rooms, 2 for the bathrooms, 0.7 for the kitchen and utility areas, so that number feels robust. I haven't got into duct lengths and pressure calcs, it seems beyond me.  I am hopeful for a sufficient sized unit to swallow any issues derived from that (for colour, our average semi rigid 75mm duct length is 8m, the longest 12m, shortest just 1.5m, with the majority between 6 and 10m, never more than 2 turns, excluding the plenum turn, 24 ducts in total).

 

When looking at the Q350, which has max 350m3/hr (equating to 0.7 ACH of my 500m3 property on full boost), achieving that 200m3/hr would seemingly mean the unit working at around 60% of it max performance.  That feels like it would be a noisy experience.  Would anyone feel confident to chime in as to whether the unit would be undersized for my needs?  Both BPC and another firm haven't hesitate to promote it based on my house dimensions.  I have read much on the site of Building regs over estimating the requirement and running their unit at some fraction of that target, keeping an eye on humidity levels to ensure the air is healthy.

 

If I need a bigger sized unit, alternatives to the Q350 would perhaps be obviously the Q450 (although the cost is really punchy), or perhaps the Brink 400, or Vent Axia Sentinel Plus B, however those later two would miss some features I like about the Q350 (or get them but for extra cost in the case of the Brink).  I have particular fondness for the enthalpy exchanger of the Q range, as my children suffer from mild skin conditions aggravated by low humidity.

 

@mvincentd, what is your take on the noise from the unit (either the ducts or the unit it self) if you are using it at around 50%?  That feels relatively high, and based on regs, I would be demanding even more from it. 

[mvincentd]

3 hours ago, tanneja said:

@mvincentd, what is your take on the noise from the unit (either the ducts or the unit it self) if you are using it at around 50%?

Well it's tangibly quieter at 35% and i've every confidence the house and air quality would be fine if that's what it ran at....i've not changed anything since it was commissioned to regs'.

Be careful how much you conclude from my example....my house is not typical, it's basically a concrete bunker, no carpets, and this likely effects sound transmission.  Also it's a branch system of 160mm diameter ducting (reduces to 125mm after 20metres) rather than the seemingly more typical radial systems.  The house shape also forces a lot of turns so for example the pic here is showing a forced deviation from what would be a straight run in an oblong house.  None of this lends itself to optimum system performance.

What i would say is don't obsess over noise...you'll buy a noisy fridge, plug in some gadget or charger that has a gentle hum to it, or have a partner that snores, all of which will render mvhr noise concerns irrelevant.

[tanneja]

@mvincentd would your instinct be that the Q350 would be sufficient given my provided property details?  No problem if you would rather not remark.  P.S. nice joists

[mvincentd]

honest answer...i don't think you should place enough value on my opinion on this for it to be worth me saying, sorry.

[andy]

On 05/01/2021 at 11:11, tanneja said:

@mvincentd would your instinct be that the Q350 would be sufficient given my provided property details?  No problem if you would rather not remark.  P.S. nice joists

 

Get Green Building Store (or I can recommend another too) to spec up a system for you that includes everything rather than guess.  Fabric-first, money well spent IMHO.

Edited January 8, 2021 by andy