New Design

[gullfo]

well you could cut into the underlying floor (leave about 1" below the plywood layer) and put the conduit there with the RIM products over top and floating the floor. if you have multiple slabs remember to isolated the conduits between the slabs with rubber couplers.

[1970428scj]

I am at the rough in stages of my build, Electrical and HVAC.
I will be using 2x 3 ton LG ducted mini split systems, using 1 for LR and ISO
and the other for the CR and Kitchen/bathroom.
Room sizes are
CR 18x23x12'
LR 19x27x12'
ISO 8x12x10'

The compressors will sit outside and the line sets will come up the outside of the building and though the vented roof , make their way over to the Air Handlers.
The AH will sit above the bathroom. Bath/kitchen ceiling is 9'. 1st leaf is at 14', the line sets will go through the ceiling to the AH on top of the bathroom in a small attic.

This way seems to be the best way to go.

A fresh air and exhaust can be tapped to the outside world easily with AH placed on to of Bathroom, Drain lines can be plumbed to the P trap in Kitchen or Bath sink.

These will be plumbed in to the duct work for fresh air, damping can be used to control fresh air? Can the fresh air intake and exhaust be Y for Both AH? This means only an intake and exhaust box at the wall.
Is a ERV/HRV necessary with a ducted AH or is the fresh air enough with the AH it self?

The AH supply and return are I think 16" duct which I believe is 1200cfm, this would mean large silencer boxes,(these boxes would need to be at least 16" inside for the first ceiling leaf thru?, then Y smaller duct to smaller boxes to each vent through ceiling leaf 2? Im sure these would need to be 10-12" ducts and boxes to stay under 300 CFMs, vent to be larger vents and 4 of them. Or dual duct long vents 4' ( not sure this exist?
Return one big silencer for each ceiling leaf, close to mid room?

The Path of each main supply and return trunk, Up to the vented roof(like the line set run) from the AH, then down through leaf 1 and 2 of the ceiling, These should be staggered?

I am no HVAC installer, I am just trying to work with the budget I have, I am yet too fined a HVAC installer that designs systems for studios, if I did, I am sure it would be out of my price range. with this equipment/ ducting etc this system is in the low $20kUSD cost. I would then need to figure the best duct sizes, silencer box build, what vents etc from there. The HVAC installer will leave ducts hanging for me to figure all this out.

I might add, I have blown by my original budget by over 2 times LOL.
The building materials, labor and subs I bring in are all 2, 3 times the cost I budgeted for this project.
I started with an already built 1200 sq/ft building that had water and sewer,
If I had to do this from the ground up it is an easy $500k-600k project here in SoCal

Glad to see the site back up!

[1970428scj]

a few photos of the roof lift

[1970428scj]

more picture of the build

[1970428scj]

well not sure why some photos are sideways and upside down sorry folks

[gullfo]

since the ceiling is solid overhead - i'd route the ducts in the trusses and drop through on the edges into in-room silencers and in-soffit ducts and plenums on the vents. you have plenty of ceiling height and the soffits up on the wall-ceiling junction will help with absorption as well as the ducting, and side lighting effects and or light bars for film lighting etc. use duct board to create the inner parts of the silencer and wrapped with drywall and put that into the soffit frame. then run flex duct to the vent location and attach to a duct board plenum to feed the low noise register. take advantage of opportunities to expand the volume along the way to reduce air speed (although you should have the lowest speed already set on your HVAC air handler - recommend a true variable speed unit so you can up the speed on times you want to run a filtering pass to clean things a bit, then set to low so it's effectively silent. also a true multi-speed compressor will help with maintaining the temperature, humidity etc, and also a proper HRV/ERV unit sized for 35% (min) air exchange / hour).

in the example: all main HVAC is in truss area with an isolated entry hatch in the live room, then distribution in the soffits. in this case the silencers on mounted on top of the ceiling as this is an inside out ceiling but the concept is the space - reduce and damp sound entry into the space, then route. basically 2 holes per room in this project.

[1970428scj]

Thanks for the reply,
The idea is to have the least amount of holes,

If the 2x AHU are in the attic space above the bathroom(there is a nice room drywall up etc, this space is large enough to easily service the ADU , space for Baffle boxes etc, it is not attached to the studio it self beside the outer shell of the building, or leaf 1. Line sets come down from the vented roof to AHU's, I would then have 2x 16" ducts supply/return per room. I can route each supply and return through the CR wall leaf 1/2 and LR wall leaf 1/2, 4x Large baffle boxes ,these ducts would then be between the leaf 1st and 2nd ceiling leaf, I would then have leaf 2 of the ceiling left to penetrate. from there I would have to have a baffle box per resister.

It is hard to even get an HVAC installer to call me back, its pulling teeth to get a quote, none of them understand the baffle box thing, MSM wall's etc They want to sell you a Motocross bike silencer. some quote loud cheaper equipment.
The LG 36k single ducted systems seem pretty good a 3 ton compressor level 54db and ADU 37db at around $5k each plus line sets etc
Have you used these before?
With both ac units , duct work, installed and I deal with baffle boxes, registers , electrical I am getting quotes of $26-35k USD, Im sure as soon as I add HRV etc its a few thousand more. My original budget was $15k on HVAC LOL.

Any tips or advice is well taken.

[gullfo]

i haven't used LG for studios. typically i use Mitsubishi most times, or whatever the local contractor can get. i just (myself) got a full blown Trane system installed for the house - it's fully variable speed compressor and air handler (whereas most times i spec a two stage compressor and variable speed blower) and it is a beast! nearly totally silent, 100% temp and humidity even when it was 100° out... but pricey... but if i was building a studio and i wanted the goods, i'd spring for the $25K...

one thing i learned during the co-engineering effort with the owner of the AC company (who also reviews all designs with their local trane engineers) is you want oversized ducts when running low speed to avoid more friction loss. so we installed 20" off the supply / return plenums on air handler to the distribution boxes and a 24" house return.

so ...

[1970428scj]

A crude drawing but this is the idea, was at work and drew this. It is basically The same Idea Stuart laid out in his HVAC post. My original thought was to try and keep weight off the Truss roof. But this is a much better plan. It is quite like yours also.

[1970428scj]

what model Mitsubishi are you installing usually? Hyper and LG red seem very close.
Not sure I really need that here in SoCal

[gullfo]

i usually spec the M series: https://www.mitsubishicomfort.com/comme ... odelID=SVZ
for in-room, i been spec'ing the cassette unit mounted into the soffit - works nicely. for computer closets - the floor mount unit is useful for cooling the server racks. and the ductless unit for situations where a full on system won't do it.

i can say that my new AC unit in a 2000ft2 house in FL, 4-tons (48K BTU) (Trane XV + TAM9) - even at a setting of 74° F, it's like a refrigerator in here regardless of the outside temp i've tried going lower (like 70°) but it seriously gets too cold (the air output temp is roughly 49° F -- basically a refrigerator) even with me cooking, baking, and open shades on the windows letting in the sun...

[1970428scj]

Thanks Glenn, Could you please explain the math for baffle boxes? I have followed Stuarts Math in his HVAC post but I want to double check.

[gullfo]

basically you need a pathway through the attenuator which approximates the area of the duct in. so let's say you have a 1ft2 duct, then your pathway should be 1ft2. then if you have 3 dividers, your minimal length of an attenuator is likely to be 60" L x 30" W x 18" D or so when you factor in the divider boards + insulation.

the air flow could be 1 cfm @ 1fpm velocity. to get 100cfm volume, then you need 100fpm velocity. etc the friction of this unit is about 30ft of 1ft2 duct (assuming you're using duct board/liner lining, which is by design, for good air flow).

see example

[1970428scj]

Thank you much! Looks like I have 2 HVAC installers now, this is what I am looking at 2x 36k either LG or Mitsu and an ERV in the system. Do I need to have an ERV per system or is one enough? This should be a nice HVAC system for my studio.

From my readings , I thought I needed to over size the box, If I am 16" at the duct I need to be bigger to slow down the air flow?

[gullfo]

if you need more than 300cfm for both, then go with two ERV units. otherwise, and presuming you'll have the two systems linked anyways due to equalising the pressure across rooms etc, then a single unit should be ok. make sure that you have easy access to the filters etc on the units because you'll want to change them every 90 days or even more frequently depending on dust, insects, etc both on the ERV and the air handlers. also filters on the exterior exhaust vent and intake vent + w/ one-way back flow valves. depending on humidity - a proper drip basin and preferably a positive flow pump for water discharge on the units to ensure they are draining.