New build small size high isolation project

#166

Thanks Starlight!

I think I will! The HVAC guy is sussing me out before he does a full quote… he’s called today to raise my expectations… he reckons it’ll be a 3.5 or 5kw ‘heat pump’ with outdoor unit, he thinks between £3.5k and £5k that’s if I do the ducting for the fresh air and of course make all the surrounding bits work like the plenums… I’ll post the drawing of the plan!

I believe his rough costs exclude the inline booster fans and dampers…

I also feel like it would be structurally safer for the fresh air in and stale out would be better as a circular core than trying to do a square hole for those boxes… then I could install the first filters just inside the building…they make these slot filter boxes I think.

#167

Purelythemusic wrote:Source of the post I also feel like it would be structurally safer for the fresh air in and stale out would be better as a circular core than trying to do a square hole for those boxes… then I could install the first filters just inside the building…they make these slot filter boxes I think.

Makes sense, it made me think of the rectangular windows on the Comet jet aircraft that suffered stress fractures over time.

Is this the kind of filter box you are thinking of? I bought one from these people, it's actually a sturdier than their photos suggest;

https://www.justfans.co.uk/duct-mounted ... -2946.html

Cheers,
Jennifer

#168

endorka wrote:Source of the post
Purelythemusic wrote:Source of the post I also feel like it would be structurally safer for the fresh air in and stale out would be better as a circular core than trying to do a square hole for those boxes… then I could install the first filters just inside the building…they make these slot filter boxes I think.

Makes sense, it made me think of the rectangular windows on the Comet jet aircraft that suffered stress fractures over time.

Is this the kind of filter box you are thinking of? I bought one from these people, it's actually a sturdier than their photos suggest;

https://www.justfans.co.uk/duct-mounted ... -2946.html

Cheers,
Jennifer

Hi Jennifer,

Yes exactly, well the one's I saw were similar, but they seem good and if you have experience then even better!

I'm also thinking a 150mm duct will be fine for the fresh air supply/return...the smallest the silencers ducting will be is 200mm. This will be handy as I have a 150mm core for my core drill! The core will be rather close to where the beams for the outer ceiling are so the shape of the arch of the top of the core will structurally spread/support the load sideways. I could easily use 200mm ducting for the fresh air but not sure how easy it will be to get 200mm core done... If I step up the duct to 200mm almost as soon as it comes in before the filter, then I think I'll be doing better for static pressure...

Ok I'm going to make a lot of (possibly unwise) assumptions (not very scientific). I believe I'll need variable speed inline fans for fresh air/stale air. These will likely set me back close to £500. My ideal option is to fit an MVHR as it will be more cost efficient to run and hopefully the mini split won't be working as hard. The one I'm looking at is about £750 https://www.vent-axia.com/range/hr200v.
I'm a bit unsure about the static pressure...I've calculated I'll need 32l/s as I'll have an average of 2 people in there at any time.
It's spec shows much higher extraction rate than supply, presumably because usually they are fitted alone to ducting from a room to the outside. The outside duct will have much less static pressure than the inside duct.
In my case I could (probably wrongly) assume the static pressure for the extract duct will not be huge, it will be greater than the supply still, but it's coming from the return plenum not the room itself. Just not sure if the unit will be either working overtime trying to pull against the flow in the return plenum, or be over extracting as there's not too much actual pressure difference.

Connected to this is I'm aware you ideally want slightly positive pressure in the room. I can use dampers to try to reduce the extraction rate but don't want to tax the motor! Ideally the extract and supply motors (there are two) would be independently wired and controllable but I'm not sure, but am trying to find out! EDIT - They are not independent. The tech guy didn't see much problem restricting the flow a bit but to be fair I don't think he really understood what I was going on about : )

Thanks for the support guys despite my long absence!

#169

Hi Tom,

I hope you're doing well?

I'm sorry if I missed this in your thread - but were you required to use small vents every metre or so just above the DPC in the concrete blocks? Or are you using exterior insulation on the outside of your blocks?

I am building my studio with concrete block outer walls, timber frame/plasterboard inner walls and was not planning on using exterior insulation. The builders are freaking out about not having cavity ventilation and so am seeking advice.

Thanks for your help,
Paul

#170

Hi Paul!

Ahhh so sorry I missed this! No I didn’t need to vent the cavity probably partly because of the external insulation 70mm EPS which is enough to eliminate interstitial condensation but also the render is less likely to let in any rain due to it’s makeup but also massive flexibility.

On top of that the roof is a warm roof construction with a concrete topping, roof covering is Liquid rubber by Kemper systems V210 the overhang is aluminium.

Basically the blocks should never get wet and the mineral wool in the cavity won’t deteriorate in the instance of interstitial condensation but it’s almost certain not to happen. Also at the foot of the outside skin of blockwork on the inner face it can drain away to the foundation hardcore between the two foundations. The inside walls are tanked on the inside just in case : )

#171

Some movement at last!

I have an air con unit! Air handler is slimline fitted to the ceiling:

It’s a 3.5kw system based on the hopeful use for the future. Won’t get into the calcs now but basically it should work well.

After this next week of work I should be able to get 2-3weeks on the silencer install and HVR installed! Should be able to do some other bits too, like I’ll need to fit the door to the inner room and the corridor floor now I know the height of the unit. The local duct place is not getting back to me so I’ll just have to get in there next week and order what I think I need!

#172

Oh I forgot to mention I’m planning to separate the silencers a little, should make connecting up much easier.

And the air con guy and I couldn’t work out why we would need complicated plenum boxes to try to take a portion of the stale air out and to put fresh in… I think it was designed that way so that only the air con unit would need to operate and that fan would do the work.

As efficiency is important With the HVR running the fresh air in and stale out (it’s variable speed), I can simply T into one of the air out ducts and use self closing baffles to stop air being pulled out of the Air Handler of the air con unit. Similar with fresh air in, self closing baffle bypassing the AHU.

Can anyone see why this might not work? I think a diagram might help show the plan…

#173

Not sure I'll be able to offer any useful insight, but diagrams are always cool!

#174

Yay! Some movement at last.

I’ve built a small floor to walk in on out of wood from the loft conversion I did last year for a customer and damaged boards at the merchant (not pictured)… can you tell I’m conscious of budget?

We are finally doing the Silencers!!!!!!!

Cut the Sorbothane Duro 50 slab 38mm thick into 50x70mm pieces to distribute under the large silencers.

Using the airbags piped together and filled with normal compressed air lifting was fairly straight forward, got about 60mm lift but relatively uneven.

Then we used litter picks to place the Sorbothane pads…perfect tool!

After spacing them evenly the compression across the pads was…uneven. Possibly because the silencers have become a bit out of shape not supported evenly, perhaps some parts are heavier, possibly the floor levelling done whilst lying down isn’t all that level (it isn’t). Anyway it cost us many hours.

We eventually reached somewhere between 15% and 23% compression (roughly). The most compressed areas were around 29mm while the least were around 32. We tweaked the position of the pads to acheive this as initially some were 26mm and others 35mm which is just out of the usable range of a spring system as far as I know, optimum being 20% but certainly between 10% and 30%.

Next is some tweaking of the position as the sleeves are not optimal in the holes in the ceiling. I want to put the sleeves in and concrete around them with a plastic covered shutter so I can ensure a caulk gap around the sleeves.

Then get the little silencers (still sooo heavy) up there sat and ducted up!

#175

Ok lots has happened! I’m just going to post the pictures and a brief description…

Okey doke.

The silencers are in on Sorbothane, all connected up with 8” duct in the ceiling void which then got 300mm minimum of fibreglass loft insulation, this was hideous to do!
Before insulating we shuttered around the silencer sleeves into the studio and poured concrete vibrating it using an sds drill on hammer… well consolidated concrete!

The small silencers could me through the finished 2nd leaf wall in the corridor which is 2 layers on cement board being careful to leave a gap between board and silencers this gap filled with silicone.

Found acoustic caulk was actually cheaper as you get almost 3 times as much for the same in high flex silicone… but it feels much less dense.

Rendered and skimmed the isolation wall and it’s painted!

Heat recovery unit installed and all ducted up including cored holes in the outside walls. Flexi duct used at some point on all runs to isolate the vibrations from the fan units.

I made a simpler decision in connecting to the outer leaf silencers…. Though I’m not sure if it was a good idea…

Studio door swinging on 8 hinges…maybe excessive… 2 drop seals and 3 stages of door stopping… 54mm door with 18+15mm mdf then 18+18mm mdf… door closer closes the door nicely but the door itself is actually a bit bowed… will see how it seals but may need a sort of latch on the inside face to force the top against the seals… the door was slightly bowed when we made it 2 yrs ago but it had been laid flat for a while and I thought that would do it.

Right now I have a problem!

With the HRV on then is a slight low frequency rumble coming through the registers! The unit is noisy when on full, but surely the silencers would handle this? There is a trickle of air coming through the 10”x8” registers so I wouldn’t have thought it would be turbulance… I’ve pressed my ear against a screwdriver at various points in the system and there doesn’t seem to be vibration transfer so it must be sound in the air itself? I’m waiting to hear back from Stuart as to fault finding…

Will update soon! Hope to be building the front wall if I get a week on it in a week or so’s time!

#176

Do you think the noise is from the fan(s)? If so, if it was me I would try putting an inline silencer after the fan(s).

#177

Have a look at this post I made a while back Tom, it was about the document EBU Tech. 3276 "Listening conditions for the assessment of sound programme material: monophonic and two–channel stereophonic" where they specify acceptable limits for ventilation and other background noise in control rooms;

https://www.digistar.cl/Forum/viewtopic.php?p=3823#p3823

It has this graph showing acceptable background noise levels at different frequency ranges. You can use it to determine if your room fits the bill. My post shows how I measured the noise using the real time analysis in REW;

I was quite surprised to find my room met the standard, even though there was audible noise with the ventilation fan on. I think Gareth confirmed a similar observation in his place. It's worth noting that your silencers are much more extensive than mine and will therefore accomplish more. I still have to add an "inner" room silencer to mine, for example.

I was surprised because I had expected the professional standard would essentially require silence. And in some ways it is, in some ways it isn't. For example I have a client who was an expert in the HVAC industry for many years and he confirmed the system was working well and meeting expectations. Other clients, friends and guests think it is remarkably quiet - like luxury air con. But if you were expecting silence, well you would find fault with it.

The thing is, once people start talking or working it basically goes unnoticed. Another perspective shifter is switching on e.g. a guitar amp in there. The noise / hiss / fizz from even a relatively modest amp without any playing happening is far more intrusive than the ventilation by a huge factor.

It's also worth bearing in mind that the backroom noise level in your room without HVAC on will be far more quiet than any normal room. Therefore even the tiniest bit of noise sticks out.

What I'm trying to get across is to make sure your expectations are in line with specifications before thinking something is wrong. There may be, or there may not be. I encourage measurement and comparison with the EBU doc to calibrate thinking.

Cheers.
Jennifer

#178

in many cases, a human's "self-noise" can easily be much higher than other noises. for a control room - if you're going to have noises (air movement, etc), try to make sure it's symmetrical around the critical listening space. so center the vents, or use a pair equally distributed. and when it comes to reflective surfaces - same thing.

lastly, at some level of silence, your "tinnitus" (that slight ring or hum or buzz) will become much more apparent (another reason why anechoic rooms suck), plus mouth and breathing etc. so a slight amount of "steady-state" noise in not unheard of, even in the most professional studios. really, a good idea is to limit how many times that noise (unmasked) is recorded across tracks when it becomes built up.

in the control room, noise happens - people noises, papers, foot tapping, humming along, etc even when lower than the material, in essence and most times, really is immaterial... sometimes it's useful when checking a mix, to add some noise (a small fan for example or, (like i do) white noise- this latter works in the room and headphones :-)

) and listen at low levels and see what comes through.

#179

Hi Guys,

Thanks so much, very helpful replies!

I will test the room and see how it is, I think the main source of the noise is the flimsy HRV box…it’s solid but thin plastic holding two fans suspended on a frame supported at 4 points… the whole thing wobbles a bit on full fan speed so I imagine it’s a fully resonant chamber! I think I could improve it by making the mounting more ridged or the box stiffer with a frame around it or something but I’ll test first.

It’s very heartening to hear of others experiences, I’m not used to any noise in the room so this was an ear opener : )

Thankfully they are symmetrical aaaand at least two of the registers will be directly above absorbers so some of the noise will be absorbed there too.

Can’t wait to build the front wall frames and get testing!!!

Thank

#180

Current setup

Soundman2020 - Studio Design Forum