Fresh Air Supply Plan for 3 room studio...

Hi, God I wish I had designed this Studio properly before I started building.... I am back to the drawing board and looking for advice and guidance regarding providing Fresh Air to the 3 rooms in my studio currently under construction. I have done a lot of reading about the subject on this forum and in Rod’s book and have a basic understanding of the fundamentals involved. However, I can’t seem to decide on what system will best suit my needs and budget (€1000 or under). I am considering Rod’s exchange chamber design but I run into problems here as my requirements are just to provide fresh air, no heating or cooling. I am also considering HRV system. So really the first thing I need to do is nail down what will be the best system for my needs and then worry about the finer details...ducting size, air velocity, amount of silencers, exchange chamber room size, fan spec, etc. Anyway here are the details of the studio...I am a complete newbie to HVAC so if I omitted any vital information please let me know The Studio consists of Control Room and Machine Room on the 2nd level, ground floor houses the Main tracking Room and the drum room. The combined cubic volume of the studio is 4312.5 cubic ft, CR = 1401.37 cubic ft, Drum Room = 918 cubic ft, Main Live Room = 1993 cubic ft. The Size is the machine room is adjustable only by its length so at its max cubic volume it can be 402 and min approx 240 cubic ft. I will need to provide approx 150 CFM of fresh air to the studio rooms CR will need 45 CFM (i have a window to open if more is needed) Drum Room will need no more than 30 CFM Main Live Room will need a max of 75 CFM If any more details are needed to help you to help me, just ask... I want to use the machine room as the exchange chamber (cooler room) and provide fresh air to CR, Main tracking Room and the drum room. There are various other multimedia rooms in the studio but they will not be linked into this dedicated Fresh Air supply and extraction system. Here are some drawings of the studio Studio - section view south Ground Floor - floor plan 2nd Floor - floor plan Whole Studio - floor plan - trace image I hope the images can help you visualize the space.... Fresh Air Supply Plan... With a view to implementing a variation of the exchange chamber design as outlined in both editions in Rod’s book, here is where I’m at. I think my machine room is a good candidate for the exchange chamber. I propose to run flexible insulated ducting from a vent in the eve of the West exterior wall. This will be my fresh air intake. The insulated ducting will connect to a vent in the west wall of the machine room (exchange chamber) filling this air tight space with fresh air. In the winter time when it gets cold here in Ireland I can heat the small machine room (exchange chamber) with a wall panel heater so the fresh air going to the studio rooms is not so cold. In the summer time (thought I hardly think I’ll need it) I can cool the air in the Machine Room (exchange chamber) with a small portable A/C. This slightly conditioned air will then be moved by natural convection down the main ducking. The ducking is then split at 3 different locations and the fresh air is directed to the respective rooms, CR, Main Tracking Room and Drum Room... This is the supply plan in its most basic form, I haven’t considered lots of variables like duct size, air volume and velocity, how to maintain the integrity of the soundproofing when the supply is entering the rooms, all my questions on these matters will come later. Fresh Air intake supply floor plan Fresh Air intake supply 3d view Stale Air exhaustion Plan... All 3 of the studio rooms will have ceiling level return vents connected to ducting which will have an inline fan extracting the stale air out of the rooms. This ducting system will run out to an exhaust vent in the eve of the west exterior wall. In Rod’s design the return air seems to go back into the exchange chamber which doesn’t make any sense to me as this would just be reticulating the dirty air, am i missing something, is this necessary to pressurise the system? Before I bombard you with a load of other questions, is the above method going to work once all the finer details are worked out? Is installing a HRV system a better option? Or does anyone have a better suggestion for providing fresh air to the 3 rooms while maintaining isolation? I wish everyone a happy new year and success in all your endeavours Warm regards hally

the return to the exchange chamber because you're exchanging the air there in sufficient quantity it is not stale... otherwise the only other consideration would be setting up baffle boxes on the penetrations to preserve the isolation of the rooms.

Hi gullfo, Thanks for your responce...

the return to the exchange chamber because you're exchanging the air there in sufficient quantity it is not stale...

I'm not sure I understand what you mean here, its seems part of the your post is missing? My initial plan was to run the return ducting (the dirty stale air) directly to a vent at the side of the building or out through the roof, either way it would be extracted directly to the outside world, back into the machine room. Just before the ducking would terminate at the exhaust vent I would put an inline fan to pull the dirty air out of the rooms... Here is a clearer floor plan, i forgot to include the return floor plan in my 1st post Thanks gullfo, hally

Sorry, just saw ur signiture, Thanks Glenn, which name do u prefer?

i'm name agnostic... sorry, i hadn't seen the returns before - venting them directly outside is fine. the idea in Rod's design is that the exchange chamber is like a normal room with AC and air is exchanged as normal, then that room air is exchanged throughout the rest of the studio. you have to have enough capacity in the exchange chamber to handle the air being cycled frequently enough not to be stale. (which is not an issue in your design). one thought is to pay attention to the possible pressure variations due to differences in the overall volume of the supply duct/exchange chamber versus the return ducts.

one thought is to pay attention to the possible pressure variations due to differences in the overall volume of the supply duct/exchange chamber versus the return ducts.

I think I understand what u mean here? (but could simplify it a bit more for me) How can I calculate or estimate what the volume of the supply duct would be if for example I was using 8" ducting? In other words, how can i know I will be supplying enough fresh air to each of the rooms, is this dependent on the CFM cababilities of the inline fan doing the extracting? To elaberate even further, the control room will need about 45 CFM of fresh air, the DRUM room need 30 CFM, the live room needs 75 CFM, how is it possible to design the system so the right amount of fresh air goes down each branch of the fresh air supply ducting? Is there any logic to placing the inline fan at on the supply ducting, would this help to regulate the supply? I suppose my worry is that there won't be enough fresh air for a comfortable working envirnoment... Question about fans... The fresh air requierments are for about 150 CFM for the whole studio so am I right in thinking I need a fan that is rated for 150 CFM or because there will be branches in the ductwork the CFM of the fan would need to be higher... What sort of noise levels are acceptable for a suitable inline fan? Can you recommend a suitable fan that is also available in Europe, I have tried to find resellers of Fantech Fans and no success... Would another simplier option be to scrap the exchange chamber idea and run a dedicated supply to each room, so this would mean 3 seperate intake ducking lines, line 1 going to CR, line 2 going to Drum Room, line 3 going to main live room... My thinking here is that the ducting could be sized according to each rooms CFM requierments... Thanks a million hally

i cannot pretend to be an HVAC engineer... that said though, you will have some loss of efficiency so if you need 150CFM then maybe you need 175CFM fan? i believe there are some online calculators for figuring out the pressure for given duct sizes and so on (http://www.builditsolar.com/References/hvacrs.htm) as a general rule - trying to keep your overall noise level down to NC25 or less is good. using low speed air movement but more volume is desirable. you could do a single supply which branches off to the other rooms and skip the chamber approach.

Hi Glenn, Thanks for your help thus far, I have contacted a few different suppliers of ductwork, etc today and I think I will will probably skip the chamber idea and run a directly line from outside branching of to each of the rooms. I'll post back later today with the final drawings and calculations and maybe you could give me your opinion on my final plan... warm regards hally and thanks for the link

Hi, I have come up with a more detailed plan for the fresh air supply and extraction from the 3 rooms in the studio, here goes... Room Details CR = 1401.37 cubic ft, Drum Room = 918 cubic ft, Main Live Room = 1993 cubic ft. I will need to provide approx 150 CFM of fresh air to the studio rooms CR will need 45 CFM (I have a window to open if more is needed) Drum Room will need 30 CFM Main Live Room will need 75 CFM The Plan Direct Supply of fresh air from an exterior vent ducted to each of the rooms. The returns will extract to an exterior vent also. An inline fan will be placed on either the intake or the extract duck line – fan needs to be able to push or pull approx 150 cfm, due to resistance, duct turns etc, it’s probably wise to rate the fan a bit higher – say 180cfm. I propose that the ducting be 8”, this will mean if the volume of air is approx 150cfm, then the velocity of the air moving thru the ducting will be around 428fpm. Before entering each room the fresh air supply will pass through a silencer (see design below) designed to double the volume of air and therefore cutting its velocity by ½. This means the air will enter the silencer @ 428fpm and exit hopefully @ around 214fpm. The supply register will be 8” x 16” and hopefully of sufficient quality not to generate any noise or a speed up in velocity. 214fpm seems to be an acceptable figure for studio air velocity from what I have read. I am restricted to 8” ducting due to joist sizes and other variables. Now for a whole lotta of questions Silencers I have tried to follow Rods guidelines with regard to building these silencers properly; I would really appreciate if someone with a bit more knowledge on their construction could take a look at my design. Are my baffles sufficiently overlapped and have I created enough volume in the box to slow the air down as I expect? Silencer Floor Plan Silencer 3d model Is this duct liner 1 ½”ok to use inside the box? http://insulationireland.com/index.php? ... &Itemid=55 In the Control Room I don’t have the space to put the silencer in the room enclosed in a soffit. Will the technique detailed in the drawings below maintain the isolation between the CR and Machine Room? The silencer will be decoupled from the machine room floor and there will be no contact between it and the outer leaf wall. There will be hard contact only between the inner leaf wall of the CR and the silencers flange... Does anyone have a source, link, advise, recommendations for affordable and suitable supply registers - 8” x 16”? Ducking Should I be trying to use rigid 8” round ducting as much as possible in the duct line or can the whole ducting be made up of insulated flexible ducking?What are the pros and cons for each? And finally, would it be more efficient to have the inline fan on the intake supply main duct or to put it on the exhaust duck just before the exterior vent? What type of grilles do I need to use for the exterior vents? Supply & Return Whole Studio Floor Plan If anything else concerns you regarding my plan, don’t hesitate to let me know... That’s it for now – regards and thanks hally

i like the silencer designs. the supply main duct needs to be large enough for the volume of air then you split off that to each of the 3 rooms. same idea on the return where possible. using pipe size changes, inline dampers? (Rod?), etc to balance the flow to the supply vents. on the CR bafflebox entry - i'd box in (around the machine room side drywall opening) to flush up the framing to the box - support and sealing.