HVAC - What to use? Is DIY an option?

Mangled · Post by **Mangled** » Fri Sep 05, 2003 5:49 am

Hey guys...looks like we're gonne get to the DIY part after all!!

This looks great!
Now if I had an AC unit that could do heating too, the setup is complete!
Stupid question maybe: what's a plenum??

Btw...Tomas, I read this post about the active noise cancelation but for me this is way too complicated

. I think I'll go for longer ducts and a more powerful fan to be sure to minimize noise.

Anyone know any formulas/calculation methods to determine duct sizes and length? Fan power/ air speed? What about AC capacity in kW for two rooms 75 m3 each? How much air (m3) would you normaly refresh per hour?

Still lots of

, but I feel it could all work out!

Erwin

barefoot · Post by **barefoot** » Fri Sep 05, 2003 6:29 am

Here is a little more about plenums. http://www.johnlsayers.com/phpBB2/viewtopic.php?t=653

As far as the active noise filter, this isn't something most people could build themselves. I was thinking more along the lines of a commercial unit that you would buy and install in your duct system. I'm not sure if anything like this is actually available. If not, maybe this is another business I should get into?!!

Thomas

knightfly · Post by **knightfly** » Sat Sep 27, 2003 5:27 am

Erwin, I'm not quite sure how this escaped me, sorry I didn't get back sooner - here's a possible unit for your situation. I would recommend getting a unit big enough to be able to run on lowest speed for noise reduction - so room size recommendations should be nearly doubled for quiet operation. (Take your total room square footage, double it, and shop for a unit rated for that size - )

Also, for maximum efficiency I'd put the inlet to your centrifugal fan as close to the cold air outlet of the AC unit as practical -

I'm wondering now about air pressures and venting the cool-room to outside instead of thru the AC unit. Eventually I may find the answer to that- I'm going to try and find an AC guy that's not so paranoid about his job that he'll actually TALK to me, LOL...

https://www.brandairconditioners.com/cg ... 8J34A.html

They don't say what voltage this unit runs on, but it's capable of heat/cool.

The only thing I know so far about quiet air for studios is that it should be down around 250 feet/minute. The noise from moving air, according to Alton Everest, increases by somewhere between the 4th and 5th power of velocity - so slowing the flow makes a huge difference in noise level.

If you actually build something like this, you could also build your own duct silencer - kind of a "slide trombone" affair, with a tunable cavity. Something like I've drawn here... Steve

Mangled · Post by **Mangled** » Sat Sep 27, 2003 6:58 am

Thanks Steve,
Today I recieved a proposal/quotation of a local contractor and guess what....They came up with the same sort of solution as you mentioned!!

The only difference is they use a split unit to heat/cool the buffer room and they propose a direct fresh air inlet for this room too. I'm wondering if it's as effective as your idea, what do you think??
By the way...estimated cost incl. installation $9000,-

Erwin

knightfly · Post by **knightfly** » Sat Sep 27, 2003 7:15 am

Might be as effective (hard to tell when you're still as ignorant as I am) but certainly more expensive. The split units are about twice the cost of the wall units like I linked to, and still don't give fresh air capability on their own. The wall units have a control for fresh or recycled air, if you set it to fresh and position your inlet/outlet to the studio rooms as I mentioned, you should be good. If you do my idea, I'd get some medium density foam and mount the AC unit floating in the wall to minimise structure-borne noise.

Interesting that they should come up with the similar idea - did you prompt them, or did they think of this on their own? Or, maybe I'm only 98% as dumb on this as I thought... Steve

Mangled · Post by **Mangled** » Sun Sep 28, 2003 11:09 pm

I didn't prompt them! It was their own proposal.
One of the things that could be important in your proposal is the tuning of the flow from the wall unit and the supply fan. If they are not exactly the same you can get over/under pressure in the buffer room which could cause more wear to one or the other device. (It's a sort of closed system).
With the split system the supply fan can get free air from outside cause it's an open system.
Nothing scientific just my thoughts...

Cheers,
Erwin

knightfly · Post by **knightfly** » Mon Sep 29, 2003 12:53 am

Yeah, like I said I have a LOT more to learn about AC - I do know that balancing pressures is one of the "biggies", just not sure how it's done yet. I think with dampers in the ducts, not sure.

The tuning device I drew would be used after everything is balanced, that way whatever frequency the main noise is at could be absorbed to cut the noise level significantly... Steve

knightfly · Post by **knightfly** » Sat Jun 05, 2004 3:53 am

Just a (major) update - I've since learned from Rod Gervais (thanks Rod, thanks to your help I may upgrade my AC knowledge from "moron" to "woefully inadequate"

Do NOT oversize AC systems for studios - if anything, they need to be UNDERSIZED a bit . As Rod has pointed out (and I actually listened) a studio generally has better heat insulation (due to sound proofing construction) than normal spaces - so, even though there may be a bit more gear making heat, using a large AC system will cause the system to "short cycle", or run for shorter periods of time. This, by itself, might not be such a bad thing; except, when that happens, the system doesn't get a chance to de-humidify the space (this requires a longer run-time), which is 'WAY NOT COOL, so to speak - humidity encourages mold and other nasty things - not to mention, if you have pianos or guitars or other stringed instruments stored there, they ALL need a RH of around 43-45% - This is also a requirement for keeping unhealthy organisms at bay.

In order to accomplish this, you would need to run either the AC or a stand-alone de-humidifier 24/7 in some areas (the entire east coast USA, for example) -

If Rod (or other knowledgeable AC people) want to add comments here, please do - however, if you have a QUESTION I would prefer that you start a new thread rather than make this into a 9-page ramble - Thanks... Steve

Mangled · Post by **Mangled** » Sun Jul 18, 2004 7:14 am

Has anyone actually checked the chiller room principle with official HVAC contractors?
I've contacted a few others since my last post and some say this could give you serious problems with freezing of the AC unit

Any comments/knowledge??

Erwin

knightfly · Post by **knightfly** » Thu Jul 22, 2004 12:41 pm

All I know is that I ran this idea past Rod Gervais, who is VERY knowledgeable on ALL phases of construction, having built everything from outhouses to major hotel chains and both movie and recording studios - he saw no reason why it wouldn't work.

Beyond that, the only personal experience I have that's close is this: My house has no central heating system, only a wood burning fireplace and some (useless) baseboard heaters - I have to sleep days 2 days a week, so don't need too much heat or light - I blacked out both windows in our bedroom and installed a slightly larger than normal AC unit in one of the bedroom windows last year.

When I'm not sleeping in there, we leave the bedroom door open and place a fairly large fan just inside the bedroom door on the floor, blowing out and upward down the hall - this keeps the entire house comfortable in hot weather, and the AC unit has worked just fine even though I need to change the mount for a bit more tilt to improve drainage of the drip pan.

Naturally, it would take more than this for sound isolation of any serious level; but for a bedroom (I sleep with ear plugs) that's not a concern.

In a sense, the bedroom is my "chiller room", and the hallway is my duct-work.

Sometimes the answers you get depend on the perceived financial impact on the person answering - smelling profits has been known to change more than one person's answers... Steve

dk01 · Post by **dk01** » Wed Sep 08, 2004 9:41 am

Hi everyone,

been reading up on Mini-Split type air conditioning and that they do not provide for fresh air or removing the stale air (instead, just conditioning whatever air is in your studio, control room etc.)

so - what about this so-called portable unit with FRESH AIR and EXHAUST AIR ducting? Seems simpler as you are just dealing with the ducts for those and not running or having any unit outside, refrig lines, and water evaproates over the internal coil etc.

12,000 BTU SoleusAir Portable Air Conditioner
http://templates.earthstores.com/1277/p ... rod=309737

SPL: 46 db/A

Thoughts?

thanks,

David

knightfly · Post by **knightfly** » Wed Sep 08, 2004 10:41 am

46 dB seems a little noisy for a studio, but if you were to use that unit in the "chiller room" approach, the only outside penetrations would be the two duct lines - then, using baffled in/out ducting to the sound room itself would reduce that 46 dB by enough to let you run the AC while recording - the downside is that a normal window unit costs less than half that, but your unit would probably give more fresh air... Steve

Post by **sharward** » Sun Aug 07, 2005 1:32 am

David's link (above) has rotted out. However, I just found this and I'm getting pretty excited!

Soleus Air MAC-10K

Could it be?

A compact, DIY wall mountable single room air conditioner and heater and dehumidifier with fresh air circulation requiring minimal penetrations that runs on 115V and only consumes 11.4 amps for only $499 including shipping?!?!?!?!?!

Please tell me that I am right to be excited about this!!!

Post by **sharward** » Mon Aug 08, 2005 11:10 am

Man, I was really hoping for some feedback on this. This seems perfect for me, and for others like me who are willing to put up with some noise in the room in exchange for all the features. The fresh air is a huge benefit -- without it I would have to tie into my house's HVAC and there are many reasons why that is not ideal!

Please, say something good about this, 'cuz I think I'm going to go for it!

Dan Fitzpatrick · Post by **Dan Fitzpatrick** » Mon Aug 08, 2005 1:56 pm

it's only me, but guess that's better than nothing?

i think it might be a good option for you, since you are not really planning on recording regularly (noise).

one thing to check is how long those ducts can be without adding up to more static pressure than the unit can handle. depending on the fan design it may not be able to handle too many turns or too long a duct. then it may not work at all or poorly.

would you vent this to outside or into your garage? i guess the garage isn't the ideal source for fresh air, but venting toward your neighbors isn't very appealing either.

you will have to figure out some isolation scheme for where the duct goes outside. any ideas?