Hi people,
I'm close to installing an external cooling unit for my home studio. I handed the HVAC guy a copy of the SAE recommendations as well as Auralex´s Acoustics 101 on the subject.
However I'm curious about a couple of things and I'd like to put them to your consideration / advice:
- The galvanized metal ducts on the exterior should have fiberglass both sides, right? (on the inside and outside of ducts). What thickness and type of insulation do you recommend? Is R-11 batt insulation ok for the inside? How about the outside? The HVAC guy said there's some insulation covered with aluminum. I'm thinking of using OW's Enduragold ductboard for the interior, what do you think?
- I know the location of the unit should be as far away as possible. Is 20 ft from the first wall ok? I'm planning on keeping the unit at this distance and use silencers where the duct enters the room.
-I'm also curious about the cooling distribution and would like your input on this. There are three rooms: CR, studio and restroom/machine room. The total area is about 18 square meters. The contractor says 1 ton is enough for this area, but considering I need to cool the equipment in the control room as well as my computer, disks, etc in the "machine room" and the heat generated inside the studio, I thought I should have a 2 tons unit. Plus that's the smallest size available for a central unit.
So I explained to this guy that the CR and machine room need more cooling than the studio room (considering the heat generated by the equipment). So we're thinking of distributing the first ton evenly throughout the whole area, and breaking the additional ton in this way: 60% Control room, 20% restroom/machine room, 20% studio room.
The size of the rooms is as follows:
CR- 3 m. x 2.70 m.
Studio- 3.12 m. x 2.60 m.
Machine room- 1.97 x 1 m.
The height of the ceiling varies and is sloped for the first two rooms. Plus it'll be covered with a false acoustic ceiling. I don't have the exact measure of the acoustic ceiling's height, but maybe you'll get an idea with the info I provided...
The whole studio is a separate construction from the house, it's about 5 ft. from the house (not too far) but enough to have the unit lay on top of the house's roof 20 ft. away from the studio; instead of having the equipment lay on the studio's roof. There'll be two input ducts and two returns. One input and return for the studio room, and one input and return for the CR. I don't think I need the extra isolation of having another set of input and return for the machine room. I think I can share the ducts with the CR, but I haven't made up my mind.
To lower the price on the project I suggested the HVAC company installs the unit with its external ducts, thermostats,etc. And I'll finish the interior ducts with ductboard, silencers, and the respective vents.
What do you think of these plans? Am I missing something? Thanks for your valuable input! Cheers!
Best regards,
Rodrigo
ps. I'm not a native speaker so excuse me if my english is lacking.
hvac installation
Originally posted at johnlsayers.com, topic 6392.
Rodrigo, your English is excellent. 8) ...Probably better than most of us "native English speakers" I might say! :)
I'm no expert on this topic, so I'll step away and let others answer your questions...
--Keith :mrgreen:
Welcome to the forum!
Personally, I wouldn't use galvanized metal duct. One reason is that I would think sounds would travel longer distances and possibly be a little louder than with other type ducts. This is including if the outside is lined with fiberglass. Now if the outside AND inside is lined with fiberglass that may work although I've never ecountered any galvanized metal duct with fiberglass on the inside and outside. If they do make that type of duct make sure the fiberglass used in the duct has a "history" of being safe for particals not breaking off and travelling through your ducts.
I believe the duct of choice (recommended) on this site is Johns Manville Superduct.
Below are some posts concerning HVAC, including a few that mention about the Johns Manville Superduct.
http://johnlsayers.com/phpBB2/viewtopic ... highlight=
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4290
http://www.johnlsayers.com/phpBB2/viewt ... highlight=
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=6374
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4106
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4878
If you can afford the Johns Manville Superduct, I would go with it first. There may be another duct that's just as good or better than this, but you'll have to do some research to find that out. After this duct I would suggest lined ductboard. It's a pretty rigid duct that's lined with some type of polymer material (I think) on the inside. I believe it has fiberglass insulation around the polymer lining with an aluminum foil type outside backing. The last choice I would use is flexduct. I used this along with the ductboard mainly because of price, convienience and construction reasons. If I could have, I went have went with the Superduct though.
I wouldn't "share" those duct lines if at all possible. Any noises from your machine room could be transmitted back through your duct. Also, because your machinery will be transmitting heat, I would run an air supply AND return there "IF" possible. If nothing else, I would have an air return line there. The one thing I would really REALLY suggest you do is research everything you want to do concerning HVAC. "After" everything is done isn't the time to say "I wish I would have"... I'm saying this because after I got finished I later found info that could have changed some of my plans. I know it may not be the popular thing to say but if you have any doubts about whether or not what you want to do will be the correct thing for your studio, S-T-O-P and research what you're in question about! Things like "how do I get fresh air in", "How will I dehumidify", "What location would be best to locate the vents?", "What are the best/quitest type vents to use and should they be oversized?", "Should I put a duct in the front where my speakers will be?" etc etc are things to consider. If you haven't already, I'd suggest you purchase Rod's book (a post is in the sticky section). It gives a LOT of info on how to figure EXACTLY what type HVAC system you need based on people, equipment etc etc. *NOTE* I'm by no means an expert, but just sharing my opinions based on info I've come across along with personal evaluation. Hope some of this helps!One input and return for the studio room, and one input and return for the CR. I don't think I need the extra isolation of having another set of input and return for the machine room. I think I can share the ducts with the CR, but I haven't made up my mind.
Having just finished the HVAC phase of my studio, I can attest to the EndraGold duct board from OC. It ran me about $38 for a 4x10' sheet. I used two ducts off of my A/C system: 1 24" x 18" for the supply and a 24"x24" for the return. They are each about 25' line.
Connected to each of these I used flex ducting (I've been told since that this may have been a mistake but at the time this was the suggested way to go). I have a separate flex line going from the register all the way back to the supply or return duct that run along the back of the building (and which is separated by a wall from any of the recording areas. I have 2 supplies and 2 returns in my CR, same for my "big" room, and a single supply and return in the vocal booth and another pair in my drum room. I ran a separate supply duct and return duct for my reception/office area. 14 duct runs in all. None of them connects through "Ts" or "Ys"
A little complicated and a lot of material but well worth it. I can turn up the speakers in the CR and not hear ANYTHING in the duct work in the other rooms. In order for sound to get from the control room to any other room (through the A/C system), it has to travel a minimum of 50' through insulated duct work.
The reason I used such large main ducts (and 8" flex duct) was to slow down the air but still get a lot of air volume. The slower it moves, the less noise it will make.
My ducts are ONLY made out of the EnduraGold board, folded up and taped. No galvanized duct work at all. The board is stiff enough (I used 1" thick) to support itself although I added a little support at the joints between 10' sections. It is very easy to work with but you should get the right tools (V cutting knife, etc).
As to finishing up the work yourself, unless you know about HVAC systems and balancing static pressure and such, you should work with the HVAC contractor to give you the design (which you can then do yourself). While it seems like it would be easy to just run some tubes to pass air, it's a lot more complicated than that and if you aren't careful, you might end up with a very quiet system that just doesn't work right (i.e., it's too hot to work).
Hope that helps a little.
len
Did you ever consider or compare with the JM Superduct? I'm wondering how they differ, if they do... Sounds like (from reading the material) they are much the same thing... and it seems like the EnduraGold is actually a bit cheaper....... I can attest to the EnduraGold duct board from OC. It ran me about $38 for a 4x10' sheet.
Why exactly is this a mistake? Is it just uneeded or is there a potential compromise to isolation (added connections, thinner materials)? Please explain...Connected to each of these I used flex ducting (I've been told since that this may have been a mistake but at the time this was the suggested way to go).
That's good to hear!A little complicated and a lot of material but well worth it. I can turn up the speakers in the CR and not hear ANYTHING in the duct work in the other rooms. In order for sound to get from the control room to any other room (through the A/C system), it has to travel a minimum of 50' through insulated duct work.
Yeah, having the galvanized seems like it could surely 'short out' things, especially if it's used in the middle of a run... I'm planning on not only using the JM SuperDuct to supply the studio, but also to replace existing ductwork that supplies rooms above the studio (this ductwork IS galv steel, and I know that it would be a big weak point, so it has to go).My ducts are ONLY made out of the EnduraGold board, folded up and taped. No galvanized duct work at all.
I have not gotten any of the tools just yet, but need to soon... Where did you get them? And where did you get the Enduragold? (maybe it's written somewhere back in your studio diary?)It is very easy to work with but you should get the right tools (V cutting knife, etc).
So, when you consulted with an HVAC contractor, did you have them come to the site, or did they just look at the plans and then draw up something? thanx for any info! K...you should work with the HVAC contractor to give you the design (which you can then do yourself). While it seems like it would be easy to just run some tubes to pass air, it's a lot more complicated than that and if you aren't careful, you might end up with a very quiet system that just doesn't work right (i.e., it's too hot to work).
I got it from my local HVAC supply company. I didn't really do an in-depth comparision but they appeared to be more or less the same product. You have to be careful on the price. When I bought my first batch of EG, it was $45/sheet so in a few months there was a $6 or so change. Perhaps the JM stuff is the same.Did you ever consider or compare with the JM Superduct? I'm wondering how they differ, if they do... Sounds like (from reading the material) they are much the same thing... and it seems like the EnduraGold is actually a bit cheaper...
The common wisdom here now (based on my reading of Rod Gervais' comments on the subject) is that flex is not the way to go. I'm not quite sure of all of the reasons. I don't think it's R value because my ED and my Flex have the same (4.3). In my case, it would not have made economic sense and would have taken much longer to install. My studio room ceiling joists are interleaved with the trusses that hold up the roof so I had to wind my duct through the trusses so to use the ED, I would have had to make triangular ducts to fit inside the trusses (some more than 40' long) and then figure out some way to get them up into the roof structure.Why exactly is this a mistake? Is it just uneeded or is there a potential compromise to isolation (added connections, thinner materials)? Please explain...Connected to each of these I used flex ducting (I've been told since that this may have been a mistake but at the time this was the suggested way to go).
The EG I got locally. The tools I got off of the Internet. The company is Malco Products and I think it took 3 or 4 days to have the V knife in my hands. There are several different knives that are used depending on the kind of cut you want. Since these run about $65/each, the only cut that is difficult with a utility knife (and do well) is the V groove you cut where you are folding up edges. If you look through my build thread, you can see what's involved in working with this material and how I made some pretty intricate boxes. Note that I decided to get the V knife AFTER building these boxes so the V cuts look pretty crappy.I have not gotten any of the tools just yet, but need to soon... Where did you get them? And where did you get the Enduragold? (maybe it's written somewhere back in your studio diary?)It is very easy to work with but you should get the right tools (V cutting knife, etc).
Ah... the advantage of living in a small town. My HVAC guy is a friend of a friend who works for Trane. He came over at the framing stage and looked at the plan for the rooms, looked at my suggested HVAC layout, and made a few suggestions as too materials, methods, and sizes. I had found a 2.5 Ton unit that a home owner was selling because the doubled the size of their house and put in a new unit. He checked it out and said it was in good condition. After we got all the duct work in, built the box for the unit to sit on (and removing the old unit), he came back Friday and soldered up all the connections and filled it with Freon. Total cost: $50! And I agreed to give his daughter an hour of recording time after I'm open. I hope that clarifies what my thinking was. I'm still looking for the HRV to install but I've already made provisions for it in the system. lenSo, when you consulted with an HVAC contractor, did you have them come to the site, or did they just look at the plans and then draw up something?
FWIW, the only reason I inclined for galvanized metal is that the exterior ducts will be on the roof, as well as the unit. It will be in direct contact with the outside world and exposed to rain, sun, wind, etc.
So the duct needs to be sturdy and I don't think ductboard is fit for that. I'm in Mexico, most of air conditioning central units around here lie atop the roofs. If I decide to go this way, I'll insulate the duct's interior as well as the xterior, and I'll only use this type of duct for the exterior ductwork.
Even though there's a Johns Manville dealer in my city, they don't carry Superduct. They said they could special order it if I bought half a trailer from them, so I don't think so. On the other hand, Vitro a mexican company is responsible for the manufacture of several Owens Cornings products; and I'm more likely to get a hold of Enduragold ductboard around here.
Thanks everyone for your suggestions, I'll let you know if I make a decision. In the meantime, I'll keep researching on this subject.
Cheers!
Rodrigo
Is it possible to at least use the non-metal duct in the places in the studio, and then use the metal duct where it HAS to be metal (for the reasons you stated)? KFWIW, the only reason I inclined for galvanized metal is that the exterior ducts will be on the roof, as well as the unit. It will be in direct contact with the outside world and exposed to rain, sun, wind, etc.
Sorry, I kind of missed that little detail about part of the ductwork being outside. One thing you might consider though is getting the thickest duct liner (for inside the galvanized part) AND seeing if you can have your HVAC contractor build some sort of "tent" over that.
The reason for the tent is because when is rains, the rain will hit the duct and it will act like a big drum being hit with little rocks and that sound will be really hard to get rid of once it gets into the duct work. You might be able to do away with the tent if you put a big silencer just inside the studio (where the galvanized enters the building.
Just a thought.
len