Air Conditioning

bolehnggak · Post by **bolehnggak** » Mon Jun 16, 2003 4:57 pm

Hi,

Me again. Hope that people aren't getting tired of me.
Still, my soon-will-be-renovated control room. Now it's the air conditioner.
It's the window type air conditioner, which makes very big hole on the wall.
Because of tight budget, I can't afford new split system air conditioner. How should I remount the air conditioner so it would minimize sound leakage in and out of the room?
And another question, my aircon is 8500BTU/h, is it adequate for a 3mtrs L x 3.5mtrs W x 3mtrs H room?

Ari

Post by **John Sayers** » Tue Jun 17, 2003 10:17 am

Ari - you have to build a new duct system for the air. Basically you build a new external duct that runs along your outside wall and creates a soundproof duct for the air to travel through before it gets to your room. I'm talking about a MDF box, lined with rigid fibreglass.

If you want to cut out the noise of the unit inside your room you'll have to do the same thing in the inside.

cheers
john

knightfly · Post by **knightfly** » Tue Jun 17, 2003 10:37 am

That's about the size for a typical (but slightly high ceilinged) bedroom - most bedroom AC's run 4500 to 5500 BTU. However, in order to keep noise to a minimum there are a few things to consider.

First, you'll need to run the unit on its LOWEST speed setting or there's no way you'll be able to control the noise. Period. Sooo, 8500 BTU gets cut in half or less.

Second, depending on the amount of gear/warm bodies in the room, you'll need MORE than the typical bedroom, not less. By the time you're done making the changes that would be necessary to use AC in that room, you'll have a pretty marginal capacity. This could be biased either way by location, and the outside temp.

Third, leaving the unit mounted in a studio wall is useless. You'll have a cool, noisy, totally NON-isolated room.

If you could build a long duct with at least 3 right angle turns, that is about the same cross-sectional area as the ENTIRE front of the AC unit, put absorption in all the turns of the duct, and put the AC unit at the FAR END of all that, you could cut down the noise a lot due to the distance and large cross-section (slower air movement) - however, if your AC unit is one that also supplies the VENT to outside, then there would probably be so much turbulence in the long duct that NOTHING would know which way it was supposed to go. Most window-mount AC units I've seen have a control option for recirculation - if you set this to NOT recirculate, then built ANOTHER similar duct for exhaust, that could work.

Problem is, by the time you do all this, you could concievably spend as much as just buying a new "split", which may not be much better for studio use from what I can see... Steve

bolehnggak · Post by **bolehnggak** » Tue Jun 17, 2003 4:18 pm

OK, these are some pictures that hopely would make things more clearly.
The pictures are the air conditioner from the outside wall and inside wall, and the duct that I would like to construct based on your suggestion. Is it possible for this kind of air conditioner?

Ari

Post by **John Sayers** » Tue Jun 17, 2003 4:29 pm

Like This

Cheers
John

knightfly · Post by **knightfly** » Tue Jun 17, 2003 6:22 pm

Ari, you'd need to do it like John's pix, only not to scale. you'd need a longer run where he's shown the vertical duct, or you'd have almost a straigh line from the AC unit to the interior. You'd also need to build another similar duct for exhaust, and set the Ac unit for whatever mode is referred to as "fresh air", not "recirculated - you want the cool air from the aC to be able to come into the inlet duct, and the warm air from the studio to be expelled by the pressure in the room, thru a similar path.

If your AC unit doesn't have the ability to JUST bring in cool air, without having to also exhaust it, I'm not sure how well the long ducts would work.

Maybe John's had success with a single duct - I've not tried it, but it just seems unlikely it would work with air trying to go both ways in a single duct... Steve

Post by **John Sayers** » Wed Jun 18, 2003 10:18 am

Yeah - you are right Steve - you will also need an exhaust duct built in a similar way, and yes the longer the duct the better.

cheers
john

bolehnggak · Post by **bolehnggak** » Wed Jun 18, 2003 4:22 pm

Well, the Air Conditioner is the type where the cool air and the sucked hot air are on the same unit.
How about this one, can I apply this?
Because the air conditioner has the cool air output and it also sucks the room air to the outside, so I figure that if I put two ducts, one for the cool air from the air conditioner, and the other is the exhaust, which looks like this picture.
If it's ok, I think I'm going to use it.

Ari

Post by **John Sayers** » Wed Jun 18, 2003 8:58 pm

yeah but that is a cycle option on the unit like the recycle air control in your car. It either takes fresh air in or returns the same air.

cheers
john

derekdun101 · Post by **derekdun101** » Thu Dec 15, 2005 9:35 am

I know this is an old post but my subject is a continuation of this so I figured it would be better to just continue this one and refresh everyone's memory. Let me know if you'd rather me start a new thread.
Here's my question(s):
1. I am planning on adding a cover/lid to front (inside) of window a/c for times when sound isolation is absolutely critical. What do you think about ways to treat and seal this lid?
2. In continuation of the chase you guys recommended above I need to consider the fact that just outside this my unit is our rear patio and patio furniture, wifes garden etc. So I was thinking about extending what John drew adding another turn going up and sending it up past the roof. Then enclosing the trap to make it look like a chimney chase. A. Do you think this will be a problem with airflow? B. Do you have recommendations on how to make this effort worth my while and not just a whole lot of work and very little results? Thanks in advance!

len-morgan · Post by **len-morgan** » Thu Dec 15, 2005 11:29 pm

I seriously think your best bet for both time and money in the long run is to do it right and NOT use this type of A/C unit. While it might be hard to imagine, every turn you put in the duct and every square inch of insulation you line it with impedes the flow of air. Think of it like a vacuum cleaner (in reverse of course). When you completely cover the end of the tube, you hear how hard the motor is try to work. That's what your A/C motor has to do.

Common window A/C units are designed for a specific purpose and a specific mounting arrangement. Changing that changes the way it operates.

I seem to recall a thread some where here where someone build a little "room" (I think out of cement blocks) that had a "window" in it. The basic idea was to cool this little room with the A/C and then have a duct come out of that room which sucked the cold air out into the studio. As long as the "sucker motor" pulled enough to keep the pressure in the room about like it would be in a normal room installation, this might work. You would still need an exaust duct somewhere else in the finished room to let the pressure (and stale air) out. You can't run this kind of set up on "Recirculate" unless you make ANOTHER provision (duct) for fresh air to get in the room. Dead clients don't pay. Lack of oxygen lowers creativity.

I guess what I'm trying to get at is that there is a minimum "price of admission" for some of these things. Sure, you could use wall paper instead of drywall. It's much easier to put up and a lot cheaper. It covers the studs so it "should" work right? A specious argument, but I think it goes to the point. You are trying to take a $200-$300 consumer wall A/C and turn it into a $2000-$3000 HVAC system. You might get it to work for a while but if the flow of air is too much less than what it was designed for, you'll be changing the motor about as often as you have to reboot a Win95 machine (!) and I'm sure the coils will freeze up a few times and need to be replaced too.

I don't mean to pee in your Post Toasties but this is how I see it. My suggestion would be to build some sort of cover for the front of the wall unit that you can put on and take off easily (and seal tightly) when you are recording. When mixing, turn off the unit. When it gets to hot/cold, stop mixing and run the A/C for a while. While you are doing this, save your pennies for a proper HVAC installation.

Sorry to rant. I've got a cold coming on and I'm a little pissy this morning.

len

derekdun101 · Post by **derekdun101** » Fri Dec 16, 2005 3:21 am

I don't mind your being "upfront". That's what I'm looking for. My problem is I keep getting the wrong information too soon and the right information too late. While I was in the building phase of this I thought all along that a front cover alone would do the trick. Now that the unit is in place and the project 95% done (5 % for acoustic treatment left to remain {thank goodness I found this site before jumping into THAT one}) I find that sound is just oozing through that unit and I'm trying to find a way too remedy it. I should also mention that the room dimensions are 12' x 16' (see picture below). If I can get some decent advice on how to make what I've got work, great. Otherwise I'm also in process of searching this site for economic ventilation options, as I live in Southern California and temperature is not an issue

Post by **sharward** » Fri Dec 16, 2005 3:40 am

derekdun101 wrote:. . . I live in Southern California and temperature is not an issue . . .

I'm from Southern California originally. Yes, the climate is great most of the time... But it does get hot once in a while (like the time I was at Disneyland and it was over 100 degrees Fahrenheit for much of the September day). Plus, a room with comfortable temerature gets "stuffy and hot" pretty quickly when you get some bodies in it. Plus, this drummer can tell you it's easy to get overheated while playing -- and that's not even counting the amps and lights that generate heat in the room.

That's not even covering the code requirement to ventilate mechanically when a room has no window. I've pontificated about that quite a bit in other threads, and I'll be happy to extend that to this one if anyone would like.

--Keith

derekdun101 · Post by **derekdun101** » Fri Dec 16, 2005 5:25 am

The more information the better. I just wanna do it right. And I've read alot of your posts Sharward so I trust your opinion.

Post by **sharward** » Fri Dec 16, 2005 5:29 am

Thanks for your misguided vote of confidence!

Here's a snippet I wrote in another thread that summarizes the ventilation requirement:

I'm quite confident that whatever codes apply in your home town are similar to those in Boise, Idaho. Why do I pick Boise? Just because they've published this lovely sheet that explains ventilation requirements in habitable spaces. In my case, the 0.35 ACH rate is actually 0.50 (i.e., more restrictive). The point is, a habitable room requires a window of a certain size or mechanical ventilation -- either of these can allow the occupant of the room to "get some fresh air in the room." Don't try to wiggle out of this requirement by saying the room won't be habitable -- if it's air conditioned, you're attempting to make it habitable, period.

Hopefully that helps a bit.

--Keith