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# Pednault's Place Theater Build - Page 2

Hopefully this floor plan is at a resolution that's legible. I've done it in AutoCAD.

Would it be better to run two individual 6" flex ducts to each of the exhaust vents and bring them together at a Y at the fan instead of using a tee inline?

And would it be better to run two individual 8" ducts to each of the supply vents bringing them together at the fan with a Y, instead of doing a tee inline?

Edited by acex008 - 9/23/13 at 10:08am

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Just purchased four Lutron Ceana 600W dimmers. Tonight I'm meeting someone to buy their Home Depot gift card that has \$430 available for \$340! That's a free \$90! Can someone review my venting/duct design so I can purchase the supplies I need to start the rough-in?
In general the layout looks workable. With my experience with the Panasonic fan, I might want the intake fan further away from the room. Also, if the fans move rated flow, an 8" duct is still going to exceed the 250 fpm recommendation. To calculate the theoretical velocity, just divide the cfm by the cross-sectional area of the duct. E.g.

C.S.A = pi x r^2 = 3.14 x 4^2 = 50.24 in^2

Convert to feet -> 50.24/144 = 0.35 ft^2

flow in FPM = 340 cfm / 0.35 ft^2 = 971 fpm.

That's the idea, but you may need to check my math.

You're splitting the flow between the inlets and two outlets, but if the registers into the room are very close to the duct, you may be able to hear the wind noise in the duct at the grille. You can use the calculations above to determine the face velocity at the grille to determine what size you need by setting the fpm to 250 and calculating the CSA from there.

CSA = (340 cfm / 2) / 250 fpm = 0.7 ft^2
What cfm are you using to come up with the 243 fpm?
Check my math:

C.S.A = pi x r^2 = 3.14 x 8^2 = 201.062 in^2

Convert to feet -> 201.062/144 = 1.396 ft^2

flow in FPM = 340 cfm / 1.396 ft^2 = 243.51 fpm

8" radius, therefore, two 8" ducts.... Not one big 16" duct...... right???
An 8" duct has a 4" radius. 8" is the diameter. The theoretical velocity will be 4 times what you calculated above.

That said, if you can fit two 8" ducts, the duct velocity may be low enough that you won't be able to hear it at the register. You still need to size the grille appropriately.

My gut feel is that two 8" ducts would work as long as you have smooth transitions and use a large enough enough grille. I don't really have any experience to back that claim up, though.

BTW, a 16" duct has a MUCH larger CSA than two 8" ducts.
I plan to run two Fantech FR150 fans at half speed to handle fresh air exchange in my 2205cu feet theater and have roughed-in everything for a ductless split to handle heating/cooling. I'm planning on delaying that purchase until I see how the room performs without it. I'm in Central Ontario.

I wired up a t-stat for the theater to control both fans using a Taco relay that Mr.Tim suggested and it works beautifully. For my "return", I installed two lengths (15 and 20 feet) of 6" insulated flex which come together at a "Y" before continuing onto the Fantech. With the Fantech pulling about 150CFM, I hear absolutely nothing at the end of the flex with my ear right up close. The real test will be after I get the theater drywalled to bring the noise floor down and install oversized "ceiling boots" which the flex with terminate into.
What do you have for the "supply" run?
Wait, wait, wait, wait, wait...

We've been assuming I'll need to run the fans at 340 cfm! That is their MAX rating at 0 static pressure!
We all know that they won't produce those numbers, but they won't have to.

Air Exchange Formula:
q = V x n / 60

Where:
n = air changes per hour: My basis of design = 6/hr
V = volume of the room: My room = 1638 ftÂ³ (not taking into account the soffits, room treatments, seating, people nor speakers)
q = fresh air flow through the room (cfm)

Entering my data:
q = 1638 x 6 / 60 = 163.8 cfm

Therefore rounding up to 165 is my required cfm needed for my space to exchange the air in the room 6 times per hour.
Now, let's figure out the cross sectional area of duct I will need stay below the maximum 250 fpm velocity.

I used this website to calculate my required CSA: http://www.borino.com/GYC/airflowcalculator.htm
Which gave me a CSA of 0.66 ftÂ². That equates to a 5.5" radius duct (11" diameter). Now because I want to split my supply into two separate ducts, I can go with two 8" ducts given that their CSA in total is 0.7 ftÂ².

Two 8" ducts pushing 165 cfm will put me at 235.71 fpm.
Edited by acex008 - 9/25/13 at 6:56am
Sounds reasonable to me.

How do you plan to control the speed of those fans? There is a three position lutron speed controller that has been used successfully, but the variable unit causes the motors to hum..... Quite loudly I might add.
Looking at the specs of the Panny fan, it puts out 34.4 dba's. I'm not sure, but I think that would be at max speed...

Now does the exhaust run of duct-work have to match identically to the supply? Meaning, do I need to run the same exact diameter and length of duct for the exhaust to meet the air exchange rate?

I was just thinking of going with the Lutron 3 speed fan controller (Model#: CTFSQ-F-BL). But I'm not sure how to figure out what the cfm will be at the three speeds! Is there a way to calculate that if I have the specs on the fan and the controller?

How does this look for the supply duct layout?

Will starting with a 6" duct for about 15 feet and then splitting into two 8" ducts within the theater be an issue?
Edited by acex008 - 9/25/13 at 7:58am
Looks good... I will be following this to see how it turns out.
Quote:
Originally Posted by acex008Â

Looking at the specs of the Panny fan, it puts out 34.4 dba's. I'm not sure, but I think that would be at max speed...

Now does the exhaust run of duct-work have to match identically to the supply? Meaning, do I need to run the same exact diameter and length of duct for the exhaust to meet the air exchange rate?

I was just thinking of going with the Lutron 3 speed fan controller (Model#: CTFSQ-F-BL). But I'm not sure how to figure out what the cfm will be at the three speeds! Is there a way to calculate that if I have the specs on the fan and the controller?

Motor hum is different from the sound of the unit running. If you don't use a speed controller at all, there will be no hum and you get the 35 dB spec (give or take). However, if you use the wrong controller, you will get a motor hum on top of the normal fan noise. If you use the three-speed controller you will probably be fine.

When I checked with Panasonic, they did not recommend this fan be speed controlled, so there are no published curves. I think you can use pump affinity laws to get a ball park though.

q1/q2 = n1/n2 I think that's right, anyway.

Cutting the speed in half should cut the flow in half. However, that relationship is for pumping something like water. Air is a compressible fluid, so I don't know how accurate that will be.

You want balanced flow into and out of the room. The configuration of the ducts does not have to be the same as long as both the supply and the return move the same amount of air.

BTW, that 6 air exchanges per hour may not be enough to keep your room cool. That number is intended as a guideline for keeping "fresh" air in the room.
I'm not overly concerned with the warmth of the room at this point. I've spoken with a couple of others who have dedicated rooms in the northern states and in Canada and they don't even have an air exchange system, nor any cooling and they have no issues... I guess I'll just throw this all together and see what the results are for my specific build! After all, this is a DIY project!

As for the noise containment of my ducted system...
I'm hoping using insulated flex duct, containing it and the fans within 24" x 24" insulated boxes using OSB, keeping the fans as far away from the HT as I can manage, and putting some bends in the duct runs, I will control the noise as best I can. Due to limited space, I won't be able to contain the duct runs once they enter the HT side...

Working on the design of the exhaust run now.
Quote:
Originally Posted by acex008Â

I'm not overly concerned with the warmth of the room at this point. I've spoken with a couple of others who have dedicated rooms in the northern states and in Canada and they don't even have an air exchange system, nor any cooling and they have no issues...

That's what this Swede hopes for too... We generally don't have AC in houses at all.
We use window AC units and take them out when the cold temperatures hit. Just picked up an aluminum step ladder, some 30# roof felt and will be buying some lumber tonight. My RSIC-DC04 brackets have been shipped and will arrive this Monday so I can secure the tops of my walls.

To do:
Move tank (doing that this Saturday)
Finish framing walls
Secure tops of walls with RSIC-DC04 clips
Frame up soffits/ceiling
Install wood blocking for speakers / lighting / accessories
Install conduit
Electrical / Lighting rough-in
Ventilation rough-in
Seal bottom plate of wall with sealant
Install insulation
Construct and hang DIY "Sound-proof" Door
Hang and tape drywall
Test to see if the single layer of drywall is enough (if not, add another layer of 5/8")
Stage Construction
Riser Construction
Carpet
False Wall Construction
Electrical / Lighting final
Paint
Wall Treatments
DIY Screen Construction
Seating
Install audio/video equipment
Setup PJ
Enjoy!
Here is the detail at my soffits along the sides of my HT. Do any of you think that the existing 5/8" drywall ceiling that will in essence become the "middle leaf" after I put up my new ceiling that won't be physically touching it be a problem? I don't want to effectively create an LFE drum!

Finally got the tank relocated! All four walls are up and I've prewired the receptacles. Next is to attach the top plate using DC04 clips. I didn't take any pictures because there's not much to look at, imagine the tank out of the corner...

I feel a huge weight off my shoulders having that tank moved! Now I can focus on the actual room!
Great!

Had to add blocking at the top plate so that I could bolt through the existing floor trusses. I'm already impressed with the results. I was pounding my hand on each of the studs to "hear" the effects. I hit the HT room wall stud and placed my ear on the stud in the stairwell wall to hear the effects the decoupling/clips. It was pretty cool to pound on each of the studs to see how much the clips reduced the sound transmission.

Next up is to start my integrated soffits. I've already hung the two short spans across the room but didn't take pics. Tonight I'll put up the long span framing members and start with the "joists". I used Simpson Strong-Tie angles and screws with hex heads and I was able to do pull ups from the center of the "beam" without any flex or signs of it coming down. I weigh 225 pounds so I'm comfortable with the strength of the connections.

I plan on spray foaming the holes around the Romex so that the wire doesn't vibrate and cause noise. After I get the soffits framed I'll rough in the electrical for the soffit lights and put up the 1-1/2" PVC conduit. I also need to order putty pads for my electrical boxes before I can insulate the existing stairwell wall. Anyone know a place I can get the putty pads the cheapest?

Progress is slow considering I only get to run downstairs and do about 15-20 minutes worth of work before the "boss" yells at me to come up for dinner...

Tank is now in the storage room!

*not sure why it rotated...
Edited by acex008 - 10/8/13 at 12:20pm
Picked up the theater seats yesterday and I brought home my GoM FR701 samples to pick out colors.

Pardon the mess!

I forgot to take a pic of the carpet but it's the one pictured below which has blue tones in it and the field color is called black but actually has dark blue/purple in it. My plan is to carpet the floor with this and a cheaper solid black for the riser and stage to save on cost.

I've also got about 60% of the soffits built.

Looking up from the HT door.

Along the left side of the HT.

From second row (knealing).

Next up is to finish the soffit framing, build backer boxes for the electrical boxes and lights, install the conduit to the PJ and to the stage and then I can insulate!
So I decided to try making my own putty pads out of the Duct Seal found in the electrical dept at my local HD. I used gloves, a plastic bag and a cardboard tube I had laying around to flatten out the thick puck that you get. This stuff is sticky! This was a trial and I think next time I'll see if aluminum foil will work better since it stuck to the plastic bag and was hard to seperate. Overall I think it should work out well and they are only \$2.48 a piece plus I have \$5 off when you spend \$50 coupons. So in all I can make 20 for \$48 after tax and a little bit of DIY labor.

I also used the foam-in-a-can to make sure my wiring doesn't create unwanted noise within the walls.

I also ran my conduit which comes down from above the soffit framing, along the stair framing and into the "hidden room" below the stairs. I can access the end of the conduit from the hidden room and this will allow me to make a nice, clean finished equipment room. More on this later.

The picture doesn't show the plastic ties I used to fasten the conduit to the framing...

I'm getting about 15 to 20 minutes a night to work on the room and about 2-4 hours on the weekends. My schedule is dictated by my better half...
So I've been lacking in keeping this thread updated with my progress.

We've decided on this carpet for the main field of the room, which is the Joy Carpets "Damascus - 1755" in black:

The riser and stage will be a standard black carpet from the big box stores. I already bought the roll of carpet pad for the room, stage and riser.

The room has been fully insulated:

The JM plastic wrapped insulation is within the stair wall and the 23" wide OC paper faced insulation is in the HT wall so that each wall has insulation.

Here is the rough opening for the entry door.

The X is where there is plywood behind the drywall so that I can install ceiling brackets to hang the front height speakers from.

I finished the storage room side of the room's wall complete with OSB and a work table. Soon I'll be building another shelf a little less deep out of OSB as well.

I received a pair of Klipsch surrounds for Christmas and purchased an AppleTV for the room.

And for the best part of this update...

I won a Panasonic PTAE-4000U projector!
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