HVAC Basics & new garage studio

[attaboy_jhb]

Hello hello!

I have had to backtrack a little in my studio design because the house we almost purchased fell through and we got another one instead. So it is back to square one but I have learned a lot so it has not been in vain thanks to the forum and especially because of the senior posters here who really know there stuff and are kind enough to share their knowledge.

So, the location of the studio will still be in the garage. I hope you wont mind my non-sketchup doodle to just give you guys a quick overview of what I am dealing with.

The stairway from the living room upstairs descends into the underground car garage via the stairs and the north part of the room will be a wash room and storage space for all our things. I plan to use the south part of the garage for the studio and want to focus on the HVAC portion before anything else. As you can see I only plan on having 2 silencers (one per leaf) and I have read that this is not ideal but can be done. Does this sound like a problem and can you give me any tips for going forward this way? What are the drawbacks if I choose to do this?

Next, you will see the exhaust silencer is connected to an exhaust fan which will remove the stale air and dump it into the spare room which has no windows. Is this a problem? The door at the top of the stair way has got a grille to allow air to pass through so I suppose this will mean that the air wont just get stuck there which is what I was worried about.

Finally, the supply silencer at the south of the room is going to penetrate both the inner and outer leaf and take in air from outside the studio. The south wall is actually a roll up garage door but I will seal this entrance and maybe even remove the garage door all together. The south wall is the only wall with access to fresh air.

look forward to your comments. Thanks again!

[Soundman2020]

want to focus on the HVAC portion before anything else

Smart move! Too often people leave that until the end, when it is way too late.

As you can see I only plan on having 2 silencers (one per leaf)

If you have one per leaf, then that would be 4 silencer, not too. You have two ducts (one taking fresh air in, one removing stale air). If you have "one silencer per leaf", then that implies 4 silencers!

Does this sound like a problem and can you give me any tips for going forward this way? What are the drawbacks if I choose to do this?

Assuming that you meant to write "one silencer per duct", implying that a single silencer will penetrate both leaves, then the drawbacks are basically this: reduced isolation.

Next, you will see the exhaust silencer is connected to an exhaust fan which will remove the stale air and dump it into the spare room which has no windows. Is this a problem?

Yes it is a problem. Firstly, it's probably illegal, since many building code regulations say that you cannot dump the stale air from one habitable space into another habitable space, and secondly even if it is not illegal where you live, it's still a bad idea.

Finally, the supply silencer at the south of the room is going to penetrate both the inner and outer leaf and take in air from outside the studio. The south wall is actually a roll up garage door but I will seal this entrance and maybe even remove the garage door all together. The south wall is the only wall with access to fresh air.

That's fine. And if that's the only place you can get an outside air path, then that's where you need to dump your stale air as well. Just make sure that the intake hood and exhaust hood are well away from each other: as far apart as you can possibly get them.

- Stuart -

[attaboy_jhb]

want to focus on the HVAC portion before anything else

Smart move! Too often people leave that until the end, when it is way too late.

As you can see I only plan on having 2 silencers (one per leaf)

If you have one per leaf, then that would be 4 silencer, not too. You have two ducts (one taking fresh air in, one removing stale air). If you have "one silencer per leaf", then that implies 4 silencers!

oops, I meant one silencer per 2 leaves sorry about that

Does this sound like a problem and can you give me any tips for going forward this way? What are the drawbacks if I choose to do this?

Assuming that you meant to write "one silencer per duct", implying that a single silencer will penetrate both leaves, then the drawbacks are basically this: reduced isolation.

Yes, thank you for being telepathic I guess you work with noobs like me so you are good at thinking for us. thanks! Ok so would I have reduced isolation even if I built a really REALLY massive silencer with really dense materials?

Next, you will see the exhaust silencer is connected to an exhaust fan which will remove the stale air and dump it into the spare room which has no windows. Is this a problem?

Yes it is a problem. Firstly, it's probably illegal, since many building code regulations say that you cannot dump the stale air from one habitable space into another habitable space, and secondly even if it is not illegal where you live, it's still a bad idea.

oh ok, well then I will toss that idea in the can but I am a bit worried now because if I put the silencer in the south, where will I put the fan? I obviously don't want to make the studio smaller if at all possible. Any ideas?

Finally, the supply silencer at the south of the room is going to penetrate both the inner and outer leaf and take in air from outside the studio. The south wall is actually a roll up garage door but I will seal this entrance and maybe even remove the garage door all together. The south wall is the only wall with access to fresh air.

That's fine. And if that's the only place you can get an outside air path, then that's where you need to dump your stale air as well. Just make sure that the intake hood and exhaust hood are well away from each other: as far apart as you can possibly get them.

Ok will do

Thanks Stuart. My name is Arman by the way and I am very pleased to have you help me out with this because your posts on this site are very clear and informative. I have another question for you. I am using a mini split air conditioning system so the copper pipes need to break through both leaves. Can you tell me how this is done so I don't lose isolation. What are the best practices for this? My outside leaf is concrete brick and my inner leaf will be drywall so the pipes coming from the compressor will pass through both leaves to get to the indoor unit. Above the studio is a patio and I may have to have the compressor up there since it may bother other neighbors if I have it on the outside of my garage
thanks again

[Soundman2020]

Hey Arman! Good to have a name!

and I am very pleased to have you help me out with this because your posts on this site are very clear and informative

Thanks for the kind words!

I have another question for you. I am using a mini split air conditioning system so the copper pipes need to break through both leaves. Can you tell me how this is done so I don't lose isolation.

Obviously, you already realized that the pipes cannot go straight across, because they would be carrying sound between the two leaves. So the solution is to bend them gently where they go through the inner-leaf, in a broad curve, until they are parallel to the wall surface, then run them up, down, or sideways along inside the wall for a few feet (meters), then bend them again, gently, wide curve, so they can exit through the outer leaf. That creates a sort of "spring" between them, which decouples a bit. But you also have to deal with the holes in the leaves: make the holes a bit bigger than the pipes, so they can go through without touching the leaf, then seal that gap all around with good quality caulk, to make sure they remain decoupled. Do that on both penetrations.

Here's an example, from a room that is under construction right now:

STVNO-USA-REAR-WALL-DSC00299.JPG

You can see where the pipes from the mini-split curve around to the left, then down inside the front of the hanger section, then they do the same thing again (but you can't see it here) where they go out through the inner-leaf, then the outer leaf.

That's the concept.

- Stuart -

[attaboy_jhb]

Hey Arman! Good to have a name!

and I am very pleased to have you help me out with this because your posts on this site are very clear and informative

Thanks for the kind words!

I have another question for you. I am using a mini split air conditioning system so the copper pipes need to break through both leaves. Can you tell me how this is done so I don't lose isolation.

Obviously, you already realized that the pipes cannot go straight across, because they would be carrying sound between the two leaves. So the solution is to bend them gently where they go through the inner-leaf, in a broad curve, until they are parallel to the wall surface, then run them up, down, or sideways along inside the wall for a few feet (meters), then bend them again, gently, wide curve, so they can exit through the outer leaf. That creates a sort of "spring" between them, which decouples a bit. But you also have to deal with the holes in the leaves: make the holes a bit bigger than the pipes, so they can go through without touching the leaf, then seal that gap all around with good quality caulk, to make sure they remain decoupled. Do that on both penetrations.

Here's an example, from a room that is under construction right now:

STVNO-USA-REAR-WALL-DSC00299.JPG

You can see where the pipes from the mini-split curve around to the left, then down inside the front of the hanger section, then they do the same thing again (but you can't see it here) where they go out through the inner-leaf, then the outer leaf.

That's the concept.

- Stuart -

Thanks for the pic, it really does tell a thousand words. When looking for a caulk, how do I know what the right one is when I go to the DIY store?

Also, I have been thinking about what you said above regarding the silencers. If I move my exhaust silencer to the south wall then is there a way I could keep the fan inside the room or would the fan have to live in its own room outside? The reason I ask is because, if I have to keep the fan on the outside of the room, then it means I have to make the studio space smaller and as you can imagine, I was hoping to keep it as big as possible,

Thanks again!

[Soundman2020]

Thanks for the pic, it really does tell a thousand words. When looking for a caulk, how do I know what the right one is when I go to the DIY store?

You could use proper acoustic caulk (acoustic sealant), but it's expensive, and to be honest, ordinary high-quality bathroom/kitchen caulk works just as well. Look for a caulk that does not harden: it must remain soft, flexible, and pliable when it is fully cured, and still stick like crazy to all the surfaces you will need to apply it to (drywall, wood, brick, concrete, metal, MDF, etc). Also, look for one that does not shrink as it dries: Green Glue acoustic sealant, for example, is know to shrink and crack if you apply it a bit too thick. Their Green Glue COMPOUND, on the other hand, is fantastic! But that's not sealant. So they have one great product, and one not-so-great product.

You'll be using a huge amount of caulk in your studio, so do some research on your own: Go to your local hardware store, and buy one tube of each type that they have, then experiment with all of them on scrap wood (and other materials) to see which one works best. When they are all dry, try stretching and twisting each one, to see which is more flexible, and also stays stuck firmly to the materials. Choose the best one, not the cheapest one!

If I move my exhaust silencer to the south wall then is there a way I could keep the fan inside the room or would the fan have to live in its own room outside? The reason I ask is because, if I have to keep the fan on the outside of the room, then it means I have to make the studio space smaller and as you can imagine, I was hoping to keep it as big as possible,

Use a fan that is specifically design for exterior, such as this one:

Fantech-exterior-exhaust-fan.jpg

That's an all-in-one combined fan, motor, and hood, that you mount on the exterior end of your duct, outside, in the open. It sucks the stale air out of your room and dumps it into the great outdoors. And due to the pressure differential that this creates, and the fact that your room is sealed air-tight, that automatically sucks air in through the intake duct.

- Stuart -