Help with Planning & Building of my Recording Studio

[Studio45]

You need 300. You have 560... Do the math.

but it's only 160 CFM haha.

There's another option here: Just live with the higher flow rate! The "6 changes per hour" thing is the recommended rate, but if you don't mind a breezy room, you can have a higher rate... Roughly double, in your case. So as long as you then double the sizes of everything to keep the flow velocity at hte registers below 300 fpm, then that's fine.

That is certainly an option, but I will leave it as a last resort. I think I could make everything work knowing I can dump some air into my storage area.

You would also need a return duct from that same storage room, back to the AHU. You need to think of this as a closed-loop system, except for the fresh air intake and stale air exhaust. The rest of the air recirculates through the AHU.

Yes of course! I should have specified in my previous post. I figure I wouldn't need to add silencers for those ducts right? since it's a storage area.

You could also do a bypass on the system, with a duct that just loops the supply right back to the return, a little way upstream. Inefficient, and frowned on by many HVAC people, but possible. However, that's a lot of extra air to bypass!!

I'd rather not go this route since I can make use of the excess in better ways.

Or you could sell that unit, and buy one half the size, which would have lower running costs, be quieter anyway, and would also provide the right amount of cooling and dehumidification.

While this is an option for sure, I'd like to avoid this one as much as possible make use of what I have right now. I understand that the running costs might be a tad lower but probably not by much.

By the way, you DID calculate your sensible heat load and latent heat load completely, right? And you check that it matches the BTU capacity of the AHU fairly closely, right? What is the total load that you will be dealing with in your rooms, in BTU/hr?

Yes I did!! With 4-5 people rocking out with 3-4 amps in the room along with computer gear and lights, etc + latent heat load I estimate I'd need a max of roughly 32,000 BTU/hr.

Note that the AHU only has a heating coil currently and for the time being I will not be installing an A/C coil/system to my HVAC. At least not for the next couple of years. In fact we don't have central A/C for our 3500 sq/ft home....yet. Having a house shaded by the forest helps a lot...the max temp the house has seen in Celsius is roughly 26-27 degrees and I've lived there for 8 years now. I have used that room in the summer plenty as a work shop for years and while it does get warm in there it really isn't that bad. The studio/garage is on the north side of the house and doesn't see/get much direct sunlight.

While I totally understand it's not ideal, I do have a portable A/C unit that I plan on using on those special days and YES I do understand how those work and have a plan on how I can make that work when needed. There won't be much sound isolation if any when I use the A/C unit but that's something I can control. Whenever we decide to get central A/C I will be putting one in for the house and also one for the studio.

In terms of heating the studio in the winter, the AHU works really well. It's surprisingly really quiet doesn't take long before the entire room is warm. I currently keep the room at around 10 degrees when unoccupied and takes around 5-10 minutes for the room to heat up to 20 when I turn the heat on.

Question about the fresh-air/HRV requirements. @30% I'd need 92 CFM. Does this mean the branch ducts going to the HRV unit has to be sized on 92 CFM and most importantly do I add that to my total CFM requirements of the AHU? Just curious to know if that is totally separate from AHU.
I know that HRV units have their own fans.

Francis,

[Studio45]

I made a bit of progress on drawing out my silencer box. Here's a quick picture that shows the sketchup model.

S45-SILENCER.png

Inlet is a 10" round metal duct that splits to two outlets. The internal CSA that goes both ways is 8.25" x 10" (82.5 in2). The outlets/sleeves will be 8" x 10" (excluding the duct liner) so in actual internal CSA will be roughly 7.25" x 9.25".

Regardless I'll be looking at getting some nice 8"x10" register grills.

Since bigger is better I designed this box as big as I could to fit on an 8ft long sheet of MDF. This particular silencer box is for the Live Room and it's a bit bigger than the requirement. I think I'll just make them all the same size and overall this should help me lower my velocity for both room, specially the control room. I've even added an extra change in direction within the box so instead of 3 I went with 4 sudden changes.

Total dimensions are: W: 20.75" x L: 95.5" x H: 13"

I'll finish the sleeves tomorrow because I'm tired and need sleep

Cheers,

Francis,

[Soundman2020]

Yup, that's pretty much the way I do it! It almost looks like one of my designs!


- Stuart -

[Studio45]

I went based on a few pictures I saw on here so chances are they are probably your design

Im wondering if there’s a preference in terms of orientation when inside the room. I was thinking of trying to put the supply box in the back of the room and the returns in the front over my computer desk and gear.

Depending on space above the ceilings I might need to put the boxes left and right but I think I’ll be okay with my first idea.

Ill draw everything out in sketchup and share once I’ve figured it all out

Thanks again for all your help and patience...I’m sure it’s very repetitive:/

Francis

[Soundman2020]

Im wondering if there’s a preference in terms of orientation when inside the room. I was thinking of trying to put the supply box in the back of the room and the returns in the front over my computer desk and gear.

That's the way I normally do it, yes. It's logical, as it takes the warm air above you, your gear, speakers, and lights, directly into the return duct, and puts the cool air down the rear wall, where it diffuses through the entire room.

- Stuart -

[Studio45]

Good day everyone!

Here's a bit more details on ducts and silencers.

I need your advice on something. Looks like I won't be able to orient the silencers like I originally wanted due to size limitations. I would lose a lot of height in both my rooms. I've even had to change the silencer design a little and moved the 10" inlet to the top of the box versus on the middle/side. I won't have much choice but to put them on both sides (to supply on the left and two returns on the right).

That's the way I normally do it, yes. It's logical, as it takes the warm air above you, your gear, speakers, and lights, directly into the return duct, and puts the cool air down the rear wall, where it diffuses through the entire room.

Do you guys see this being a big deal? The only way I could see them potentially on the front and back would be if I shrunk the box length wise to only have 3 total sudden changes versus 4 and even then I'm thinking that wouldn't make much different.

Here's a few pics that show how I currently plan to put everything in place. (supply is on the left and return is on the right)

S45-SILENCER-S2.png

S45-SILENCER-S1.png

I'm thinking it won't be an issue but wanted to get your opinions first.

Cheers

Francis,

[Gregwor]

Do you guys see this being a big deal? The only way I could see them potentially on the front and back would be if I shrunk the box length wise to only have 3 total sudden changes versus 4 and even then I'm thinking that wouldn't make much different.

Here's a few pics that show how I currently plan to put everything in place. (supply is on the left and return is on the right)

Yes, this is a big deal.

You should ideally have your supply and returns as far away from one another as possible. One at each end of the room. That way, all of the air in your room is being thrown/sucked/exchanged not just the little bit between the two on your ceiling in your current design.

I see you're feeling the wrath of HVAC now

Maybe design your boxes in a U shape. Can you picture what I mean? That way you can still split your RD duct into two paths, but that way you'll be able to situate your supply outlets at one end of your room and your return inlets at the other.

Greg

[Studio45]

Yes, this is a big deal.

That's what I thought, I knew it was too good to be true haha.

You should ideally have your supply and returns as far away from one another as possible. One at each end of the room. That way, all of the air in your room is being thrown/sucked/exchanged not just the little bit between the two on your ceiling in your current design.

Right and I will do my best to make that happen. Unfortunately though, both rooms are not that big and if I want to make use of every inch of space I don't have much choice but to put the boxes over my ceilings and having slopped ceilings certain adds a challenge. I'll figure something out.

I see you're feeling the wrath of HVAC now

Yep! I sure am, but it's not that bad. I'm happy and thankful to have great people like yourselves helping away and making sure I don't make any major mistakes.

Maybe design your boxes in a U shape. Can you picture what I mean? That way you can still split your RD duct into two paths, but that way you'll be able to situate your supply outlets at one end of your room and your return inlets at the other.

Sorry, I'm not sure I understand what you mean, any chance you can draw something real quick to give me an idea? :/.

Last night I worked on a few other different designs to see what would fit best and I think I'm getting closer but still have to find the right one.

Question: I'm wondering what is ideal for the design, A) Have more sudden changes in direction or B) Have more than double the inlet CSA as a pathway inside the box?

I'll share the different designs I sketched later tonight with hopes that I find the right one.

Cheers!

Francis,

[Soundman2020]

Sorry, I'm not sure I understand what you mean, any chance you can draw something real quick to give me an idea? :/.

Imagine taking the two extreme ends of your current silencer design, and bending them around until they touch each other. Like taking a bar of steel and bending it into a horse-shoe shape, or a "U" shape. So you'd have your duct connected at the base of the "U", and the registers next to each other at the far ends of the "U".


- Stuart -

[Studio45]

Ok, I see what you guys are saying. I'll draft something out and share later

Thanks guys

Francis,

[Studio45]

OK!! I think I've finally found something that works. The boxes don't have as many sudden changes in direction as the previous ones I had drafted but I believe these will work great. You'll see that I had to angle the outlet a little in order to have them spaced out as much as possible.

Here are a few pics to show what I mean.

S45-SILENCER-D3.png

S45-SILENCER-D1.png

S45-SILENCER-D2.png

Here's another example of a bigger box that has a few more changes in direction. I might try and use those for the Live Room since I've got a bit more room to work with.

S45-SILENCER-D4.png

Let me know what you think

Francis,

[Gregwor]

Not exactly how I pictured them, but those should work as well! My only question is how will you get your AHU hooked up to those?

Greg

[Studio45]

Not exactly how I pictured them, but those should work as well!

I think so as well. After having measured everything this design was the best I could do width wise. Even length wise I had to shrink them down from the second design above. The slopped ceilings are really a challenge but I'm happy with the results of the boxes. I'm happy that I was still able to make them bigger than the min requirement as this should help me with reducing velocity. The internal pathway is 8" x 10" (80in2) and the outlet sleeve is 8" x 12". That's 20in2 more than the minimum for the CR and with that size I can maintain a ceiling height of 8ft. As for the Live Room I'll try and use the second design above. That design has a few more changes in direction but have the same internal pathway and 15in2 more CSA than the minimum required.

My only question is how will you get your AHU hooked up to those?

Here's a quick picture of my original idea.

S45-HVAC-D1.jpg

I'll be running supply and return branches in between the inner leaf walls of the rooms. Basically the ducts will run all the way up against the ceiling from the floor and then run parallel with the support beam (on both sides supply on one side and return on the other) over the silencer box and then down
to connect in the middle with some adjustable elbows.

I'm currently adding more details to my sketchup plan that shows the framing details of the walls and ceilings, along with the ducts. I'll post pics once I've got that done.

Cheers!

Francis,

[Soundman2020]

Here are a few pics to show what I mean.

Looks like it should work fine, but I would double up on the baffle thickness at entry and exit: Imagine tracing a straight-line path directly from the duct entry point to the register outlet point, and seeing how many obstructions you hit, and how thick they are. If all you find is one thin layer of MDF, then you should do something about that!


- Stuart -

[Studio45]

Thanks Stuart! I'm glad you think these will work!

I would double up on the baffle thickness at entry and exit: Imagine tracing a straight-line path directly from the duct entry point to the register outlet point, and seeing how many obstructions you hit, and how thick they are. If all you find is one thin layer of MDF, then you should do something about that!

I'm sorry, I'm not sure i get what you mean by this. Are you saying the far end corners at entry point should have some sort of 45 degree angle on them and same at the exit point? Any change you can draw over my pictures to show what you mean?

Francis