MHRV Noise/Bathrooms

Curious Geroge

Finally got the MHRV installed and commissioned in the past week. Its a zehnder 550 unit. I was curious to know from anyone with a similar system, is ther a noise from your supply and extract. Mine is very shallow noise like an airplane is the distance, you really don't hear it until its silent at night. It's not something that would keep you awake but I wondered if this is the same for others. The system itself is set at "2" and the commissioned report says its running at 48% efficiency. The bathrooms are not on a boost (unit does not support boost or humidity) but the mirrors do steam up, is this the norm ? The bathroom itself clears within 5 mins after a shower.

Calahonda52

48% efficiency for a PHI approved unit?
This is ridiculous
http://www.zehnder.co.uk/comfosystems/index.php?pageID=63&ProductOverview:category=&category=&template=18_product_detail.html&product_detail:oid=58
is the spec sheet
Are you at 2 or Level 2, which is 70% of max so even if u at Level 2 why can't you up it to Level 3 even for a few minutes

Curious Geroge

Calahonda52 wrote: »

48% efficiency for a PHI approved unit?
This is ridiculous
http://www.zehnder.co.uk/comfosystems/index.php?pageID=63&ProductOverview:category=&category=&template=18_product_detail.html&product_detail:oid=58
is the spec sheet
Are you at 2 or Level 2, which is 70% of max so even if u at Level 2 why can't you up it to Level 3 even for a few minutes

Hi Calahonda52, the switch is at 2, I dont know the difference between your statement on "2 or Level 2", is there another setting ?

On "why can't you up it to Level 3 even for a few minutes", why ? I'm wondering if anyone else is experiencing a noise, this would just amplify the noise level. If your referring to increasing to level 3 for showers, the unit is on another floor so you would'nt expect to do this at the unit for every shower you take and the system seemingly does not support boost which is only available on the next model and its too late now.

Calahonda52

open the link and click on the technical tab and scroll down for 2 vs Level 2, assuming I have the right unit

Have u no control panel like for normal heating?

Any" boost" yes will move the air everywhere faster for a while but it is MHRV with a theoretical efficiency of close to 95 %

How many silencers were fitted and where?

What was the design flow rate for normal operations vs the Level 3 max of 460m3/h

Curious Geroge

Calahonda52 wrote: »

open the link and click on the technical tab and scroll down for 2 vs Level 2, assuming I have the right unit

Have u no control panel like for normal heating?

Any" boost" yes will move the air everywhere faster for a while but it is MHRV with a theoretical efficiency of close to 95 %

How many silencers were fitted and where?

What was the design flow rate for normal operations vs the Level 3 max of 460m3/h

Afriad I can't answer all the questions.

There is a control panel on the unit itself but I've not touched that as it seemed to be set there during the commissioning and its not the most intuitive of panels.

No silencers fitted that I'm aware off (any pic of what these look like?)

Calahonda52

From Google https://www.google.ie/search?q=mhvr+silencers&lr=&safe=images&source=lnms&tbm=isch&sa=X&ved=0CAgQ_AUoAWoVChMI3oiPwpfdxgIV6Y7bCh0klwbT&biw=2560&bih=1235

they look like car exhausts.

Re the manual, see the pdf below, have u the Luxe version.
Did u get the 3 or 4 page commissioning report as shown in the manual?

Curious Geroge

Calahonda52 wrote: »

From Google https://www.google.ie/search?q=mhvr+silencers&lr=&safe=images&source=lnms&tbm=isch&sa=X&ved=0CAgQ_AUoAWoVChMI3oiPwpfdxgIV6Y7bCh0klwbT&biw=2560&bih=1235

they look like car exhausts.

Re the manual, see the pdf below, have u the Luxe version.
Did u get the 3 or 4 page commissioning report as shown in the manual?

No luxe version
No commisioning report yet

http://info.zehnderamerica.com/blog/why-are-some-hrvs-ervs-so-noisy
"Some HRV/ERV systems, such as Zehnder’s, are built in with sound attenuators (or silencers) to minimize noise."; makes me wonder if more are needed.

Calahonda52

1: you need to get the design spec for the project:
air flows, duct sizes, etc etc.
2: get the tech spec for the exact model you have.
3: itemised invoice for all the kit installed

Curious Geroge

Calahonda52 wrote: »

1: you need to get the design spec for the project:
air flows, duct sizes, etc etc.
2: get the tech spec for the exact model you have.
3: itemised invoice for all the kit installed

Thanks; I was more interested to know if this is a common noise or should one expect complete silence.

Calahonda52

Curious Geroge wrote: »

Thanks; I was more interested to know if this is a common noise or should one expect complete silence.

It all depends on the design which is why u need the data above.
High flow rates in crap ducting that is too small in diameter will give noise.

low flow rates in wide diameter ducting with noise attenuators will just leave the unit as the noise source so how is it mounted?
fixed to concrete wall with rubber shock absorbers or sitting on the ceiling rafters?

Given what you have posted here nothing would surprise me

Curious Geroge

Calahonda52 wrote: »

It all depends on the design which is why u need the data above.
High flow rates in crap ducting that is too small in diameter will give noise.

low flow rates in wide diameter ducting with noise attenuators will just leave the unit as the noise source so how is it mounted?
fixed to concrete wall with rubber shock absorbers or sitting on the ceiling rafters?

Given what you have posted here nothing would surprise me

It is fixed to concrete wall with rubber shock absorbers.
2 x 75mm ducts to each supply and from each extract

Is any level of noise common in the correct setup ?

Calahonda52

download a sound app onto your phone/tablet and do a noise test in the bathroom or wherever: leave the phone down on, try to have it at head height, and try be as quite as possible, take the reading and look up the spec on the technical tab.
There will alway be some noise as its a mechanical plant with two elec motors so yes it won't be 100% silent.

Without having the math on the cals, house size etc 2 by 75 is not useful.
You really do need to find out what it is running at, can't help anymore till you provide this info.

hexosan

I've a beam unit 12" duct from outside vent to unit. 10" across attic, 8" to first floor bedrooms and 8" to two rooms on ground floor 6" to the rest due to height restrictions.
There are baffles installed back from the vents in the ceiling. Unit isn't commisssioned yet. Is it better to have the larger ducts to reduce the sound.

Calahonda52

hexosan wrote: »

I've a beam unit 12" duct from outside vent to unit. 10" across attic, 8" to first floor bedrooms and 8" to two rooms on ground floor 6" to the rest due to height restrictions.
There are baffles installed back from the vents in the ceiling. Unit isn't commisssioned yet. Is it better to have the larger ducts to reduce the sound.

yes because say you have a requirement of 210m3/h and a preferred max flow rate of 2.5m/s and there are 3600 seconds in an hour, gives a cross sectional area of 0.0237m2 which is a 170mm dia duct or a 300mm by 77mm rectangular duct. { number from a project on my desk:eek:] 210/(2.5*3600)

So if u make the duct bigger, the flow rate will drop and via versa, lower speed is less noise, don't know if there is a min flow rate I have seen a range of 2 to 3 m/s

As well as the baffles, do u have silencers in line?

hexosan

Yeah silencers installed as well.

893bet

This was one the reasons I went with the Teed off system. The 75mm pipe used in the manifold system seemed a bit small to me and I was concerned about flow rate.

Curious Geroge

I had a couple of PM's re this thread but just for the wider followup; The unit it the zehnder 550 hrv unit; its a manifold system; the noise is not from the unit which is quiet but from the supplies in the rooms; simply put, its a HUGE waste of money, stress and time; the only work around is to have a 3 way timer switch installed so its on a very low setting at night - thus, why bother..

rampantbunny

Curious Geroge wrote: »

I had a couple of PM's re this thread but just for the wider followup; The unit it the zehnder 550 hrv unit; its a manifold system; the noise is not from the unit which is quiet but from the supplies in the rooms; simply put, its a HUGE waste of money, stress and time; the only work around is to have a 3 way timer switch installed so its on a very low setting at night - thus, why bother..

Does the noise keep you awake (can you get used to it)? Is there mould in your house?
If no to the above, while it's not ideal for you without boost function, it's probably still doing it's job.

The lack of automatic boost/humidity detection would bother me TBH, but sleep is more important than fogged up mirrors. I expect some noise from my system (not installed yet), but any hotel room I've ever stayed in has always had some background ventilation noise and I even find it relaxing. A bit of white noise (as long it is consistent) is OK with me as it can drown out other noises. Even working here in office, there is constant noise from what must be 24" ducting. When the ventilation rates reduce after hours, it is a very quiet place. You can hear every key press on the keyboards it is that quiet - too quiet.


On the lack of boost/humidity detection; I'm no sparks, but if you can lower the system level at night on a timer, you should be able to boost your system using the same approach. Instead of a timer changing the system level, a humidistat does the same thing. Should be able to place a stat in the return duct into the system and wire from there.

Curious Geroge

rampantbunny wrote: »

Does the noise keep you awake (can you get used to it)? Is there mould in your house?
If no to the above, while it's not ideal for you without boost function, it's probably still doing it's job.

The lack of automatic boost/humidity detection would bother me TBH, but sleep is more important than fogged up mirrors. I expect some noise from my system (not installed yet), but any hotel room I've ever stayed in has always had some background ventilation noise and I even find it relaxing. A bit of white noise (as long it is consistent) is OK with me as it can drown out other noises. Even working here in office, there is constant noise from what must be 24" ducting. When the ventilation rates reduce after hours, it is a very quiet place. You can hear every key press on the keyboards it is that quiet - too quiet.


On the lack of boost/humidity detection; I'm no sparks, but if you can lower the system level at night on a timer, you should be able to boost your system using the same approach. Instead of a timer changing the system level, a humidistat does the same thing. Should be able to place a stat in the return duct into the system and wire from there.

Its not noise from the boost, its noise from the normal running of the system. We have to put the system down to run at speed 1 at night and back up to 2 during the daytime. Could we get used of it ? Nope, its like having a plane fly directly over the house. The unit has no boost for the mirrors etc..

rampantbunny

Curious Geroge wrote: »

Its not noise from the boost, its noise from the normal running of the system. We have to put the system down to run at speed 1 at night and back up to 2 during the daytime. Could we get used of it ? Nope, its like having a plane fly directly over the house. The unit has no boost for the mirrors etc..

I understand that CG. I was splitting the issue into two, firstly the noise, secondly the lack of boost.
As you said you were reducing the system to level 1 via a timer at night (therefore you can change the levels via a signal), I was suggesting using a similar mechanism to increase to level 3 when humidity is detected.

galwaytt

...I have an 'old', i.e. early HRV unit, and yes, there's (some) noise - esp as the unit is mounted directly above the bathroom. On the GF you can't hear anything. I actually don't even notice it anymore.

But I have to say, not having a 'boost' functions is distinctly odd imho.

There's also HRV unit in the room next to my office and is a much more advanced (aka, expensive unit), and it is noticeably noisy. Not being a manifold system, and the first outlet being in my office about 2m from the unit means I've got the jet noise too. Again, I don't notice it anymore, but in a house it would be an issue.

rampantbunny

galwaytt wrote: »

...I have an 'old', i.e. early HRV unit, and yes, there's (some) noise - esp as the unit is mounted directly above the bathroom. On the GF you can't hear anything. I actually don't even notice it anymore.

But I have to say, not having a 'boost' functions is distinctly odd imho.

There's also HRV unit in the room next to my office and is a much more advanced (aka, expensive unit), and it is noticeably noisy. Not being a manifold system, and the first outlet being in my office about 2m from the unit means I've got the jet noise too. Again, I don't notice it anymore, but in a house it would be an issue.

What diameter ducting is used for the 'old' setup?