John Sayers' Recording Studio Design Forum Archive

An ERV or HRV (they are not the same!) can recover a large percentage of the energy that would otherwise go overboard. Very recommendable. But there's also the issue you mentioned, of dumping too much air overboard when you didn't need to. The REAL reason you dump the stale air is CO2. You want to get rid of the CO2 that people are exhaling. Most people think that if you seal your head in a plastic bag (or an air-tight studio), that you'll die from lack of oxygen. Actually, you won't: long before the oxygen level drops low enough to kill you, the CO2 level will have risen to many times the level that will kill you. You can die in air that has plenty of oxygen in it, but way too much CO2. So you dump the stale air overboard, mainly to get rid of excess CO2. But commonly, you dump more than you need to! If only there was a way to detect the CO2 level in the room air, and only open the "dump" valve if the level is too high . . .

Yup, you guessed it; there are sensors you can buy for your HVAC system, and controllers to go with them, and motorized damper valves... put it all together, and you have a system that regulates the flow of stale air (and make-up fresh air) based on the CO2 level. so when it is just you in the studio, the damper valve is nearly closed, and only a small percentage of the re-circulation air gets dumped, but when there's a whole band in there, sweating an huffing and puffing, the system detects the much higher CO2 levels, and opens that valve wide, so it dumps far more bad stuff (and sucks in far more good stuff). Yes, that adds extra expense and complexity to the HVAC system, but the cost will be offset by the reduced need to cool that incoming make-up air.

Combine that with a good HRV (or ERV if you live in a climate region where that makes more sense, and uf you have ore money.... ) and you can have a very efficient system that doesn't waste much energy in the air that it dumps.

Again, Stuart, great stuff!!

when i dream of my new system (what, you don't dream of AC systems?) it has a way to switch over, 100%, to outside air if needed. So... like i said earlier, i feel like I'm constantly running the AC (perhaps at 75) when the outside temp is 65 (or even 55). Seems like a system would be very efficient, financially and "green-ly", if there was a way to have it simply use the fan(s) to pull the stale/warm air out and replace it with clean/cool air from the outside. And then, if the outside is not cold enough (which would be often) i would kick in the AC and do a "50/50" type situation.

I've found some very inexpensive inline ducts that have a motorized louvers, and (in my mind, at least) this would be easy to set up in two places, to allow for this sort of a design.

Example: right now, as i type this, the AC is set for 75, and in 3-4 hrs it will be close to 60 outside.. and then i should be able to switch over to 100% fresh air to cool the room... that's my goal.

more to come!

If your room meets all those specs (like this one does: www.johnlsayers.com/phpBB2/viewtopic.php?f=2&t=20471 ), then you have an absolute top-quality, world-class room. OF course, it's not easy to get there!

WOW!!!!!!

Nicely done!!

There's three basic rules here: No dimensions that are direct multiples of each other, or within 5% of being a direct multiple. Plus these two:

l < 3h & w < 3h
(translation: "Length less than three times the height, and width less than 3 times the height")

1.1w / h < l / h < ((4.5w / h) - 4)
(Translation: "Multiply the width by 1.1 and divide by the height. That result must be LESS THAN the length divided by the height, and BOTH OF THOSE must be less than the width multiplied by 4.5 divided by the height, less four.")

As long as your dimensions meet those, you should be good. Some other things to take into account: Recommended floor area for a control room is minimum of 200 square feet, maximum of 600 square feet. If you really want to get into all the technical specs, then google download the document "ITU BS.1116-3". Thta lays out the exact specs for a critical listening room. Skip the first few chapters, as they are not applicable: chapters 7 and 8 are what you need. If your room meets all those specs (like this one does: www.johnlsayers.com/phpBB2/viewtopic.php?f=2&t=20471 ), then you have an absolute top-quality, world-class room. OF course, it's not easy to get there!

Stuart - this is great.. I did the math and it looks like I'm pretty well in the clear. The only area that's close is the height vs width. The place i'm looking at now has 11.5' high ceilings, and the plan calls for a 24' wide control room. This is all still at the "fact-finding" stages.. so the available space can change, BUT the theory remains the same, and that's why I'm here. SO: If i have a control room that's 11.5' high, making the width less than 24, that could prove problematic? (11.5 x 2 = 23.. straight multiple). And, 24 even would be cutting it close? Better to start at 25 or so, yes? (or 21) - in other words i want to be Plus/Minus 5% of 23, right?

Then, of course, we're faced with the reality of: ok, sure, it looks (and sounds) right - but it's too narrow for anyone to want to book the room, so... moot point, eh? (i'm speaking in broad terms, of course..)

Another Question: A few studios back, i had a machine room. This was a HUGE plus. Especially since that control room was VERY quiet, so even having a laptop in there (with a fan going) was disruptive. It really made me see and value the benefits of having a LOW noise floor in the control room! I found that i started to mix at lower volumes, and genreally adapt a more zen aproach. I miss that.

So I'm looking to incorporate that into this design, at some point as well. The obvious choice would be in the front, somewhere, since there is that false wall and all that space (along side the bass traps, potentially). Do you have any pics of that detail from that studio you designed (and linked to) for Rod? I believe there was something similar there? (hidden door?) Maybe adequate to just have something like "half a closet" built into the front wall, with a door to the control room...

I also presume there is some theory there, in regards to air flow, cooling, etc? In the old days, i had a separate window unit for that room, with its own thermostat. Seemed to do the trick, even if not the most elegant solution.

when i dream of my new system (what, you don't dream of AC systems?) it has a way to switch over, 100%, to outside air if needed. So... like i said earlier, i feel like I'm constantly running the AC (perhaps at 75) when the outside temp is 65 (or even 55). Seems like a system would be very efficient, financially and "green-ly", if there was a way to have it simply use the fan(s) to pull the stale/warm air out and replace it with clean/cool air from the outside. And then, if the outside is not cold enough (which would be often) i would kick in the AC and do a "50/50" type situation.

Weelll...... There's a problem with that approach. HVAC systems don't just deal with temperature and fresh air: another very big part of HVAC is controlling humidity. Your studio should have a fairly constant relative humidity of around 40%. Your instruments (especially ones that use wood or other natural fibers in their construction) will swell and shrink as the humidity in your room changes, and both the tone and tuning will therefore change... Probably not what you want when you are trying to repeat takes from yesterday, when it was sunny and dry out, but today it's raining and foggy! Some gear and some mics also like to have constant humidity...

Fortunately, HVAC systems take care of that. There's two types of heat that air conditioners get rid of: latent heat, and sensible heat. "Sensible heat" is the type of heat that you are talking about when say the air is hot or cold. Latent heat is the type of heat you are talking about when you say the air is "muggy" or "clammy" or "dry". When the warm, moist air in your room moves through the coils of the HVAC unit, the first thing that happens is that excess moisture in the air condenses on those cold coils. The simple act of that water changing phase from gas to liquid, means that heat was released. That heat is carried away by the coolant in the system. So the system removes a lot of heat from the air... but the temperature of the air did not change yet! The only heat that was removed at this point, was "latent" heat: the heat that was stored in the gaseous state of the water in the air, but then released as the water changed phase to liquid. So heat was removed, but the temperature didn't change. Then, now that the air that has been relieved of its excess water load, as it continues to move over the rest of the coils in the HVAC unit, it can cool down: That's the "sensible heat" part of the equation.

OK, so what does all that mean? Firstly, if you forget to take BOTH of those heat loads into account when you dimension your HVAC capacity, you could end up with a system that is only able to remove the humidity (latent heat), but doesn't have enough "power" to also remove the sensible heat. So the air comes out drier, but still warm. And if you then pump in warm air from the outdoors, the room will end up getting hotter, not colder, even though the HVAC system is running at full capacity, maximum speed, and 100% duty cycle. It will wear out real fast like that, since it is overloaded, and even so still can't handle the job.

"So!" you say to yourself "I'll just get one that is bigger than I need! Has extra capacity, beyond what my room needs!". That's just as bad. If the unit has too much capacity, it will dry out the air too much, cool it too fast, then go into standby with just the fan running but no compressor... and stay like that for a long time, until the air gets moist and warm again. In other words, the duty cycle will be very short (just a small percentage of the time actually doing it's thing, then the rest of the time just moving air). Which means that the temperature and humidity in the room will swing wildly from extreme to extreme, all the time! A sudden blast of icy, dry air that yanks the temperature and humidity way down, then a slow build up again to high humidity and high temperature... rinse ... repeat....

The point being? Don't try to do stuff that won't work! Yes, it's nice to think you are saving power, and saving money... but in reality you are not. Instead, follow the guidelines to correct size your HVAC system: It needs to have the capacity to deal with the highest latent heat and sensible heat load that your studio will ever conceivably have, on the hottest, dampest day in summer with a dozen musicians jamming breathlessly, working hard and sweating hard and breathing hard (which greatly increases both the temperature and humidity in the room....), plsu all the gear turned on and running at max levels, plus beer and pizza (more heat, more humidity)... and the HVAC system needs to be able to deal with that, without overloading or running beyond about 90% duty cycle... but it also needs to be able to deal with the situation where it is just you in there, sitting quietly, listening, with minimum gear and lights on, on a cool dry day in winter, late at night. The system has to be designed to deal with both extremes: enough capacity to handle that highest load and still keep everyone cool with the humidity under control, while also not freezing your butt off at the other extreme.

So, the VENTILATION part of the HVAC system needs to be adjustable (preferably automatically, controlled by sensors and a system controller) such that it always dumps the right mount of stale air and also provides the corresponding amount of make-up fresh air from the outside world, as needed for each situation. You could do it yourself, manually, sure, but you'd soon get bored rushing around checking the temperature, humidity and CO2 levels in each room, then adjsuting the dampers, fan speeds, and air flow rates... then adjsuting it again when the pizza arrives, or when Joe fires up his new 10,000 watt bass amp, or three musicians suddenly take a break in the green room, or a couple of WAGs arrive unexpectedly and want to sit in on the session in the control room... I think you get the picture! That's not something that you want to be trying to handle manually. Just install a system controller, sensors in each room (and outdoors), and let the controller do its job.

So, that's my rant for the day on why your plan might sound good on the surface, but isn't practical, and wouldn't work anyway... Sorry!

I've found some very inexpensive inline ducts that have a motorized louvers, and (in my mind, at least) this would be easy to set up in two places, to allow for this sort of a design.

Probably not! See above...

As a point of reference, when I design a studio from scratch, I often end up spending as much time on the HVAC system as I do on the entire rest of the studio! Lot's of things to take into account, and juggle... It's big. Way bigger than most people realize.

Example: right now, as i type this, the AC is set for 75, and in 3-4 hrs it will be close to 60 outside.. and then i should be able to switch over to 100% fresh air to cool the room... that's my goal.

If you had a proper system, designed and programmed correctly, you would leave the temperature set at 70 ALWAYS; and allow the system to do it's thing: It will decide when it can use more outside air... but it will consider the humidity of that outside air, and decide if it would waste more power in removing that humidity than it can save by not needing to cool the air as well... If you bring in humid air (you live in LA! It's ALWAYS humid!) then that needs to be dehumidified (latent heat removed), which means the compressor has to run to do that, even if the air doesn't need cooling! It still has to to the work of cooling the coolant, pumping it through the pipes to the indoor unit, so the cool humid air can flow over it to have its excess humidity removed, but then NOT be cooled additionally... all of that takes electrical power to accomplish: it would probably have been more efficient go just circulate the warm-but-already-dry air that is in the room, and cool it a bit WITHOUT needing to first remove the latent heat, because it is already at the right humidity.... If the humidity is high, it takes a lot of power to remove that latent heat, but the slight extra sensible heat from cooling recirculated room air isn't such a big deal, probably....

Just follow the usual guidelines. With a good HRV (or ERV) and a good AHU / Heat Pump combination, with sensors and controller, it will be very efficient, and you won't have to worry about it. It will be a "set and forget" system. If you use one of the ultra-efficient "inverter" HVAC systems, then it's going to be very, very efficient. I guarantee that you would be totally unable to make it more efficient by trying to manually adjust the make-up air ratio... and very likely you would make it far less efficient, as the system would have to fight against your decisions all the time, to fix what you messed up....

more to come!

Yup!

Edited to add... :

feel like I'm constantly running the AC (perhaps at 75) when the outside temp is 65 (or even 55).

Then your system is likely either not designed correctly (inadequate capacity for dealing with high latent heat), or IS designed correctly and is doing its job perfectly: removing latent heat but NOT cooling air that doesn't need cooling.

If the compressor is running at a high duty cycle (eg, more than 70% "on"), then likely it is a design issue: wrong system for that job. If it is running around 30% to 60% duty cycle, it's probably doing just what it is supposed to do.


- Stuart -

If you had a proper system, designed and programmed correctly, you would leave the temperature set at 70 ALWAYS; and allow the system to do it's thing: It will decide when it can use more outside air... but it will consider the humidity of that outside air, and decide if it would waste more power in removing that humidity than it can save by not needing to cool the air as well... If you bring in humid air (you live in LA! It's ALWAYS humid!) then that needs to be dehumidified (latent heat removed), which means the compressor has to run to do that, even if the air doesn't need cooling! It still has to to the work of cooling the coolant, pumping it through the pipes to the indoor unit, so the cool humid air can flow over it to have its excess humidity removed, but then NOT be cooled additionally... all of that takes electrical power to accomplish: it would probably have been more efficient go just circulate the warm-but-already-dry air that is in the room, and cool it a bit WITHOUT needing to first remove the latent heat, because it is already at the right humidity.... If the humidity is high, it takes a lot of power to remove that latent heat, but the slight extra sensible heat from cooling recirculated room air isn't such a big deal, probably....

Just follow the usual guidelines. With a good HRV (or ERV) and a good AHU / Heat Pump combination, with sensors and controller, it will be very efficient, and you won't have to worry about it. It will be a "set and forget" system. If you use one of the ultra-efficient "inverter" HVAC systems, then it's going to be very, very efficient. I guarantee that you would be totally unable to make it more efficient by trying to manually adjust the make-up air ratio... and very likely you would make it far less efficient, as the system would have to fight against your decisions all the time, to fix what you messed up....

Thanks Stuart. As always, clear and on point! It's all coming together now.. albeit slowly (but that's why I'm here!). I've read a LOT about HRV, and I like what I'm finding. It's a clever idea, and makes total sense. Not entirely free ($$) but i like it. It's a big job, and I'm intrigued and fascinated with all I'm learning here.

I had a thought that every single room maybe wouldn't have to be cooled.. or vented.. but the more i think about it, that's probably not a good idea (read: the fainting singer) = especially if the doors to the ISO booths (for example) are not sliding glass doors, but double doors on pumps (i.e. always closed). So.. ideas come and go, almost as quickly as I can come up with them. Which is kinda part of the brainstorming (and the fun)

Would you feel comfortable sharing any sketches of your designs? As far as HVAC?
Rod's super-studio, for example?

I'd really want to have two (smaller) systems: one for the control room and one for the recording spaces (I do a LOT of mixing and mastering, so cooling an add'l 1000sf of recording space would be wasteful)
Would i then (since i do so much mixing, and so much work mostly alone) only want to add the HRV unit to the control room only?
And save money?
Or just figure that in the scheme of things, an added $1k (?) for an add'l unit is worth it, and the clean, fresh air for those big band-tracking dates (every room occupied) will make people so happy that i should just go for it.

I know.. a lot of "what if's" and speculation.. sorry.

A lot of reading, the last couple of days.. and Stuart is right, a LOT to learn!

One thing that is (still) a mystery to me is the actual placement and _connection_ of the (presumably home made) duct silencers.

If, in my design, i have a large rigid duct feeding the control room (for example) I'd want to have the silencer somehow IN the wall, going into the room, no?
And if so.. which leaf is it actually connected to, and which one isolated from - and then, how?

Same would go for the other rooms
I can't seem to see it in my mind. . . the box somehow must 'live' between the leaves, essentially?
Or is it best - if i have the space - to hang it from the ceiling (in a hallway?) outside of the room(s) and then 'penetrate' carefully through the outer leaf, via flexduct perhaps, and then terminating tied to the inner leaf / register?

Does this make sense?

Also: i imagine the same would hold true for a control room that has a large rigid duct across the ceiling, as a supply? I assume the duct-silencer(s) would always have to be AT/IN the point entry, through the wall (the 2leaves) yes?

Lastly: (getting ahead of myself again) - bonus question: what is the "de rigueur" way to get cables and things through our fantastically constructed and sealed 2 leaf walls? i always see the 'ol 4" PVC pipes in studios here in LA - with foam stuffed in either end after the cables are run through), which now i realize are TOTALLY killing the isolation btw the two leaves (!).
Perhaps a PVC pipe on either end with a rubber or cloth coupling between the two? (where the air gap would be in the walls)

Hope you all had a fab weekend!

Ideally, both your inner and outer leaf silencers should live between the walls. Some people will fully decouple the boxes from the walls and have them sitting on their own stands so they are only touching the concrete. You could probably go super hardcore and mount them on sorbothane or 703, but personally, I feel that is a bit overboard. For the times we are unable to fit them between our walls and have them only touching the concrete, we have to mount them to the walls.

For the penetration through the sheathing, you must leave a small gap (maybe a few mm or so) around the sleeve. The sleeve is typically just an extension of the box itself, being made of the same material and thickness to maintain the surface density of the silencer. So, usually a square or rectangular sleeve made out of MDF. You're right in saying that the silencers are typically right at the point of penetration. Often, people will just throw a register cover over the penetration and be done with it (if they are able to have the silencers at the rights spots in their rooms).

If you need to run duct work inside your room like you said, you can use normal duct with liner to get it wherever you need it. Obviously you will want to frame it in and stuff insulation around it.

You connect the inner and outer leaf silencers with flex duct or a flexible duct connector like Durodyne. You do NOT use it for the penetration as it does not have the surface density needed to not trash your isolation.

Regarding cable runs, it personally freaks me out. As far as I'm aware, the standard practice is to have at least 2 bends in the pipe, have a flexible connector in the middle (unless you're running the conduit through concrete), and yes, stuff the ends. From there, you can also run the pipe into a box/panel where you can seal it up. The crappy thing is that conduit is light and doesn't have much surface density, and therefore, it sucks for maintaining isolation. Luckily, with fresh ground up builds, it's easy (considering) to run conduit under ground. For retro-fit builds, you can do it if you bust up the concrete. Maybe one of the pros can chime in here with some more knowledge bombs to help out!

Greg

I'd want to have the silencer somehow IN the wall, going into the room, no?
And if so.. which leaf is it actually connected to, and which one isolated from - and then, how?

It all depends on how much isolation you need, which is another reason for starting out your entire project by defining that: settling on a number: the number of decibels of isolation that your situation merits. If you only need low to moderate isolation, then you can probably get by with a single silencer on each duct, where a solid, massive "sleeve" on that silencer will pass through both leaves of the wall, without touching either of them. But for the typical case where you need moderate to high isolation, you need one silencer box on EACH leaf, for EACH duct. In other words where each duct has to pass through a wall, there is one silencer box on the outer leaf, and one on the inner leaf. Usually they are linked by a short section of flexible duct.

If that's the case, and you are not shooting for very high / extremely high isolation, then each silencer box could touch the leaf it is associated with, but if you do need that very high / extreme isolation, then you would decouple each box from the leaf, by making the hole a little larger than the "sleeve" of the silencer box that goes through it, then using highly flexible caulk to seal that gap between them. That's also where you'd want to use Sorbothane to decouple the box from the structure that is holding it in place, to eliminate any possibility of sound flanking through the box and into the structure. I did that a couple of years ago, for a customer who has a drum teaching studio in his residential house: With two drum kits in there, playing together and synchronized as he teaches drums to his students, there was a need for very high isolation. In that case, the silencers were actually fitted in between the ceiling joists, with close tolerances around them, so it was very important to maximize isolation.

I can't seem to see it in my mind. . . the box somehow must 'live' between the leaves, essentially?

It can if you want, and if you have enough space for that. Another option is to have the boxes inside the rooms and outside the outer leaf. Generally, I try to put the silencer boxes in the ceiling space, wherever possible, since you normally do want to have the registers in the ceiling in any case, so it makes sense.

and then 'penetrate' carefully through the outer leaf, via flexduct perhaps,

The actual penetration through the leaf CANNOT be flex duct. That would be sort of like water-proofing your roof very carefully, but then cutting a large hole in it and covering it with a piece of cloth...

Think of it this way; the silencer box is an extension of the leaf itself. It has to have similar mass to the leaf, and also create an "envelope" that mass outwards from the exact point where the "hole in the leaf" starts, all the way to the point where the duct connects to it.

to get cables and things through our fantastically constructed and sealed 2 leaf walls? i always see the 'ol 4" PVC pipes in studios here in LA - with foam stuffed in either end after the cables are run through), which now i realize are TOTALLY killing the isolation btw the two leaves (!).

Yup! Very true. For a studio that is supposed to get you high isolation, that would be a pretty bad plan...

Perhaps a PVC pipe on either end with a rubber or cloth coupling between the two? (where the air gap would be in the walls)

You mean like this? :
Yup! That's how to do it. Here's the concept:

- Stuart -

Greg, Stuart. Thank you for this.

This all makes a lot more sense to me now!
I read something a while back - from one of you - where we were talking about supply and return silencers (the need for both) and i remember being confused by the number(s) you came up with.

It's all clear now - i.e. 4 per room (yikes)

PROVIDED that's the isolation I'm going for - but yes, looking at each silencer as a part of each leaf brings it all into focus now. (btw.. i used to make these silencers - huge ones - as a teenager, when i was working in the metal shop.. and i used to HATE that stuff.. the liner.. stingy and itchy.. I'm sure there are more 'humane' options available today.. this was ages ago! = so full circle here.. amazing!)
Thank you.

NEXT: the question of "how much isolation do i need?"

This is actually a good question (which is why Stuart asks this at the beginning of every post he replies to ) - being the pro he is!

And oddly, even if I've been making records for over 25 years now, and worked in all the best studios over the world (a lot of them, anyway) I've never really considered an actual dB number for isolation. Usually it's more of a "hmm.. there's a bit of leakage from the drums into THIS iso booth but not so much into this one", or similar.. As opposed to "hmm.. that sounds like roughly 50dB of isolation.. not bad "

All i know is that I want it to be really great (ha!).
I have a (ahem) Radio Shack SPL meter (I've ordered the one recomended in the REW thread, the white one, btw) and it does have A and C weightings on it. Perhaps a good place to start would be to actually see where my current studio stands, as far as isolation, and try to get a dB number here. Another mystery to solve, and another brick in the foundation here. Maybe that will help determine what I'm actually trying to do
Any tips on how to make that measurement? Besides the 'obvious' (i know... shot myself in the foot again) which would be "play some music loudly, measure SPL in room, go to other room, close door, measure SPL" ??

Ok, onward and upward!!
Thanks again.

PS = yes.. the 4" PVC straight through both leaves.. you'd be amazed to see how many times I've seen that. In "real studios" - i like the idea of angles and rubber couplings!

Any tips on how to make that measurement? Besides the 'obvious' (i know... shot myself in the foot again) which would be "play some music loudly, measure SPL in room, go to other room, close door, measure SPL" ??

That is, indeed,the way to do it!

If you could get an actual band together to play in the room, live, with their normal instruments and gear, and tell them to go crazy, that would be the best. If not, you can get close with a good full-range speaker system playing music that covers the spectrum well. In both cases, set the meter to "C" and "slow", measure inside the room at least 3 feet away from the speaker / band, then measure in many places outside the room: in other rooms, outside the building, upstairs, down stairs, near, far. Make several tests with different music genres.

Then send everyone home, and measure again in the same places with all the gear turned off, late at night, when it's really silent...

Also check your local "noise regulations", to find out what your legal limits are: It's one thing to set a level that you think is nicely quiet, and doesn't annoy the neighbors... but the law might have a different view on how loud you are permitted to be on your own property.... IT would be sad if you invested all that money in building a superb studio, then you get the cops knocking on your door every day while you are tracking, and writing nasty things on bits of official paper that cost you a lot more money! It pays to do your homework....


- Stuart -

Thanks Stuart!

this makes a lot of sense - I'll get on it!
a day of SPL!!

btw.. a lot of research and a lot of calls re. ERV systems, and setups.
making good headway.

there are two schools of thought, as far as i can tell:

1 - set up ERV as a wholly separate system, with its own ductwork (major work.. extra silencers etc)

2 - set up ERV integrated to HVAC system, get thermostat with IAQ access/port - have the two talk to each other and run in tandem. I.e. supply form HRV added to supply in system before control room, and same on the return. ERV then has its own fresh air intake (from outside) and exhaust (to outside). this all sounds very good and well.. and the units are not crazy expensive (sub $500 for example) - so i guess the key here would be to have a tech/installer that knows what he's doing

perhaps the first question would be "hey.. you heard of ERV??" when i audition HVAC guys

onward!

2 - set up ERV integrated to HVAC system, get thermostat with IAQ access/port - have the two talk to each other and run in tandem. I.e. supply form HRV added to supply in system before control room, and same on the return. ERV then has its own fresh air intake (from outside) and exhaust (to outside). this all sounds very good and well.. and the units are not crazy expensive (sub $500 for example) - so i guess the key here would be to have a tech/installer that knows what he's doing

Yup! That's the best way to do it.

But are you SURE you need ERV? HRV is less expensive, and less complex for cleaning / maintenance.... Is there a real and substantial advantage to ERV in your climate? I'm not so sure that it would be justifiable where you live.


(PS. If you do the SPL test using speakers, make sure you are getting a level of at least 100 dBC inside the room, preferably closer to 110 dBC (measured at 3 feet). Use hearing protection, of course...)


- Stuart -

But are you SURE you need ERV? HRV is less expensive, and less complex for cleaning / maintenance.... Is there a real and substantial advantage to ERV in your climate? I'm not so sure that it would be justifiable where you live.

well, again as with everything: conflicting reports.

to be honest, i'm not decided yet.
some manufacturers say HRV is mainly for (like the name says) Heat Recovery.. i.e. heating up the incoming cool air (during the winter) - not an issue here.

some say to get the ERV since it does both.. AND is does a better job regulating / dealing with moisture.

my main goal, as we talked about, would be to introduce some (more) fresh air into the system / control room (more than the standard HVAC could do) and thus lower the number of hours per day i actually need to run the AC.

for example: outside is cool, inside is warm (gear, people, etc) and it's 6pm.. the idea of being able to switch the AC off and run the fans in tandem on the HVAC and ERV is appealing.

of course, whether that's an actual reality remains to be seen, but that's what i have been able to glean from pages and pages of documents and pdf's, downloads, calls with reps, manufacurers, dealers, etc.

THEN: if my research into this reveals that a properly adjusted and well designed HVAC system will do this nicely on its own (like you touched on last week), then I'm all for it. I'm not really seeking out more work / more $$, per se.. just doing my due diligence, i suppose

By the way.. my studio always smells kind of like socks, but i'm not entirely sure that's not just because of an impoperly balanced HVAC system that's in there already. Or maybe just actual socks...

PS - roger and 10-4 on the SPL! thanks..

some manufacturers say HRV is mainly for (like the name says) Heat Recovery.. i.e. heating up the incoming cool air (during the winter) - not an issue here.

HRV is very simple: it transfers heat from the warmer air stream to the cooler one. That's it. If the warmer air stream is the INCOMING air, then the heat in that stream is transferred to the COOLER air stream, which is going out. So the outgoing air (which was cool to start with) gets warmer, and the incoming air stream (which was warmer) gets cooler! And that's EXACTLY what you want in a warm climate: You want to recover the "coldness" of the outgoing air, by warming it up... which obviously means the other air stream gets colder... the air coming IN! Think it through...

ERVs also deal with humidity (not moisture). If there is a large difference in humidity between indoors and outdoors, then it can be useful. If you have high humidity outside, then removing that humidity in your HVAC system would use up a lot of it's capacity (remember the whole "sensible heat" and "latent heat" thing. You could use a dehumidifier in the room instead, but that also uses electricity.... What an ERV does is to transfer some of that incoming humidity to the outgoing air, so that you don't have to deal with it in your system. So if you have high humidity outside, then can be worthwhile. On the other hand, if you have very low humidity outside, and would need a humidifier in the room to replace the lost humidity, then an ERV can be useful. It transfers the humidity from the outgoing air stream to the incoming air stream. However, if the outdoor humidity is similar to the humidity of the air inside the rooms, then there's no point to using an ERV, since the savings won't be that great.

So, you'd need to know the typical outdoor relative humidity in YOUR area: if it is in the range say 30% to 60%, then an ERV won't help much, since the transfer won't be very efficient. But if the outdoor humidity is less than about 20% or more than about 80%, then it can make sense.

Otherwise, HRV.

some say to get the ERV since it does both.. AND is does a better job regulating / dealing with moisture.

Only if there is a worthwhile difference between the humidity in the two air streams. If the humidity is similar, then the effect is not worth the expense, or the complexity.

my main goal, as we talked about, would be to introduce some (more) fresh air into the system / control room (more than the standard HVAC could do) and thus lower the number of hours per day i actually need to run the AC.

That would be the WRONG goals! Your goal should be to introduce the CORRECT amount of fresh air into your system, as mandated by ASHRAE specifications and local regulations, then to minimize the cost of running suh a system by recovering as much of the "wasted" energy as possible, within reason. An HRV can easily get you 80% heat recovery, and some approach 90%. If there's a substantial difference in humidity levels, then an ERV can gain you a few more points, while also saving a bit on the capacity side.

for example: outside is cool, inside is warm (gear, people, etc) and it's 6pm.. the idea of being able to switch the AC off and run the fans in tandem on the HVAC and ERV is appealing.

The idea is appealing, sure but the concept is flawed. You are forgetting everything I mentioned about keeping your HUMIDITY levels constant... unless you happen to like the tone of all your instruments changing thorught all your sessions, so that early takes do not sound the same as late takes, and you also like wasting time every few minutes as all the musicians have to re-tune their instruments, since not only do the TONE change, but also the TUNING changed, due to the swings in humidity.... and as long as you don't mind the changes in vocals too, due to the differences between singing with dry air, moist air, or "correct" air... and the complaints about sore throats ... and the damage you'll be doing to all instruments that have any wood in them or other natural fibers (eg: reeds, skins, etc...), and the changes to the tone of your condenser mics, some ribbon mics, and even some electret mics... plus the changes in the effect of your acoustic treatment as it absorbs or releases moisture, due to the humidity swings... as long as you don't mind all of that, and can deal with having no return customers and ever-declining revenue, then your plan is fine and wonderful! Or you could just do what ASHRAE says, and avoid all of that...

if my research into this reveals that a properly adjusted and well designed HVAC system will do this nicely on its own (like you touched on last week), then I'm all for it.

Yep. It will.

If you think you can do this manually, then here's an experiment for you: Set your HVAC system to "cooling only", set the thermostat as low as it will possibly go (maybe 40°F?), set up a humidifier in the room, and also a dehumidifier, get a hydrometer (device for measuring humidity) and a thermometer, and a CO2 meter, and set them all up in front of you. Now each time the temperature goes over 69°F, turn on the HVAC manually, and each time the temperature goes below 67°F turn it off manually. At the same time, as soon as the relative humidity goes above 45% turn off the humidifier and turn on the dehumidifier, but as son as the level goes below 35% do the opposite: turn off the dehumidifier and turn on the humidifier. And while doing that, also monitor the CO2 level: as soon as it goes above 350 PPM, open the door to "let the stale air out and bring in fresh air", then as soon as it goes below 300 PPM, close the door again. Take care that NONE of those levels goes outside of those ranges! Be very meticulous about that. Now do all of that while also critically listening to some raw tracks you have, and making a good mix out of them, then mastering that... Do that for a few hours every day, for the next ten days or so, and tell me how much you like the concept of trying to handle all of that manually! And tell me how well you were able concentrate on your mix... and how well it turned out.

Or you could just install an automated HVAC controller with sensors and electrically controlled dampers...

By the way.. my studio always smells kind of like socks, but i'm not entirely sure that's not just because of an impoperly balanced HVAC system that's in there already. Or maybe just actual socks...

Assuming that it's not just socks... ( ) to me that would indicate two things: insufficient fresh air intake / stale air exhaust, and lack of humidity control. It might also indicate that your HVAC system is too small for the load you are placing on it (not enough BTU/hr capacity). Plus, it also indicates that it desperately needs a thorough cleaning and maintenance visit from a qualified HVAC technician, who will not only change the filters and check the coolant pressures, but will also clean out all the grunge from the fans, cooling cools, and registers, then spray the entire air path with anti-bacterial mist...

It probably also means that your acoustic treatment devices were not designed / built / maintained properly, and will need replacing. There's not much you can do to porous absorbers that have picked up your sock smell...

- Stuart -

Thanks again, Stuart!

All good and sensible information in here.
It's not a simple thing, navigating the internet. Trying to determine what is needed, what is not - and ultimately trying to really determine what the problem at hand is. Or, if there even IS one.
I believe you, when you say a properly designed, adjusted and set up HVAC system will more than likely acheive everything I'm looking to do.
And the HRV / ERV.. who knows? Maybe I won't even need it (I'd love that = more money for microphones)
But like i said.. due diligence

I apreciate the time and thoughtful responses here. Tremendously insightful.
I will continue my research, and hopefully get to the point of being able to design a proper HVAC system when the time comes.
(or at least get to a sensible starting point, and then submit here, for review )

Onward!
-Husky

Quote:
my main goal, as we talked about, would be to introduce some (more) fresh air into the system / control room (more than the standard HVAC could do) and thus lower the number of hours per day i actually need to run the AC.
That would be the WRONG goals! Your goal should be to introduce the CORRECT amount of fresh air into your system, as mandated by ASHRAE specifications and local regulations, then to minimize the cost of running suh a system by recovering as much of the "wasted" energy as possible, within reason. An HRV can easily get you 80% heat recovery, and some approach 90%. If there's a substantial difference in humidity levels, then an ERV can gain you a few more points, while also saving a bit on the capacity side.

Quote:
for example: outside is cool, inside is warm (gear, people, etc) and it's 6pm.. the idea of being able to switch the AC off and run the fans in tandem on the HVAC and ERV is appealing.
The idea is appealing, sure but the concept is flawed. You are forgetting everything I mentioned about keeping your HUMIDITY levels constant... unless you happen to like the tone of all your instruments changing thorught all your sessions, so that early takes do not sound the same as late takes, and you also like wasting time every few minutes as all the musicians have to re-tune their instruments, since not only do the TONE change, but also the TUNING changed, due to the swings in humidity.... and as long as you don't mind the changes in vocals too, due to the differences between singing with dry air, moist air, or "correct" air... and the complaints about sore throats ... and the damage you'll be doing to all instruments that have any wood in them or other natural fibers (eg: reeds, skins, etc...), and the changes to the tone of your condenser mics, some ribbon mics, and even some electret mics... plus the changes in the effect of your acoustic treatment as it absorbs or releases moisture, due to the humidity swings... as long as you don't mind all of that, and can deal with having no return customers and ever-declining revenue, then your plan is fine and wonderful! Or you could just do what ASHRAE says, and avoid all of that...

Quote:
if my research into this reveals that a properly adjusted and well designed HVAC system will do this nicely on its own (like you touched on last week), then I'm all for it.
Yep. It will.

If you think you can do this manually, then here's an experiment for you: Set your HVAC system to "cooling only", set the thermostat as low as it will possibly go (maybe 40°F?), set up a humidifier in the room, and also a dehumidifier, get a hydrometer (device for measuring humidity) and a thermometer, and a CO2 meter, and set them all up in front of you. Now each time the temperature goes over 69°F, turn on the HVAC manually, and each time the temperature goes below 67°F turn it off manually. At the same time, as soon as the relative humidity goes above 45% turn off the humidifier and turn on the dehumidifier, but as son as the level goes below 35% do the opposite: turn off the dehumidifier and turn on the humidifier. And while doing that, also monitor the CO2 level: as soon as it goes above 350 PPM, open the door to "let the stale air out and bring in fresh air", then as soon as it goes below 300 PPM, close the door again. Take care that NONE of those levels goes outside of those ranges! Be very meticulous about that. Now do all of that while also critically listening to some raw tracks you have, and making a good mix out of them, then mastering that... Do that for a few hours every day, for the next ten days or so, and tell me how much you like the concept of trying to handle all of that manually! And tell me how well you were able concentrate on your mix... and how well it turned out.

Or you could just install an automated HVAC controller with sensors and electrically controlled dampers...