Kinetic River Cinema - Page 7

And time to get some darn pictures up. All this reading is giving me a headache.

That is going to be crazy. I'm loving it. Cannot wait to see some details on that.

Really nice progress and work! I am glad that back box design will suit your needs.

I think it would be best to address my opinions on the above with a few bullet points:

• He is correct that the sizing of the diffusors is the very last thing to be considered. Doing a thermal load calculation is the first step - did he say how many BTUs of cooling were required for the theater? Only once this is done would be be able to tell you the size and number of ducts running to the theater zone.
• I have seen many new construction homes where there are essentially holes in the walls to each room with return air grates on either side acting as dead vents so return air can escape back to a common conditioned space. Simply said, a forced air system with proper supply and returns is more than sufficient, making any dead vent totally unnecessary. It is no secret that I am not a fan of dead vents UNLESS they are being used for soundproofing as part of the forced-air HVAC system supply or return and NOT supplemental ventilation unrelated to the primary HVAC system. What did he say about creating additional supply for the room if you move forward with your dead vents and separate in-line fans to force along the ventilation??
• He is correct regarding the thermostat for the theater - but this is where the addition of mechanical dampers to your existing system would come into play to prevent over-cooling or over heating in the other primary area. What did he say about the possibility of adding dampers? It is unlikely that 100% of your HVAC's output should be diverted to either heat or cool this one room, so some of the dampers added to the upstairs (or other part of the basement) supply and return would have to be let open to get a proper cycle time vs. a 3 minute blast of artic air and then shutting off.
• I don't like the idea of a mini-split.....at all. Although they are fairly quiet, they still make noise which is totally undesirable for your theater, not to mention the expense of the install.
• I guess since he was talking about 45 and 90 he was thinking of using sheet metal for the supplies and return(s) which I would not do. I would use insulated flex duct if at all possible. You will still have a metal starting collar and perhaps an elbow if you have insufficient radius to bend the flex. But if you have the room and the ability to use flex, then use flex. If you must have metal ducting for less resistance and increased pressure, then you do what you have to do to get it mechanically "right". Just insulate and use a dead vent in this scenario, if possible.

Again, these are only my opinions based on my past research, education and projects involving HVAC. They are the true experts but as you pointed out - they may not have (i.e. probably not have) specialized knowledge on theater HVAC system setup. I am a bit surprised he didn't start with a heat load calculation as his very first step - it sounds like he didn't do one at all.

What's your procedure for this?

Sounds like the HVAC guy was a bit over his head, but he still should have been able to tell you the number and size of supplies, the thermal load calculation, etc. The fact that he did none of this would make me want to move on to the next company like you did. Perhaps you can interview a number of them by phone and set the expectations of what you are looking for a bit more before having a guy out so the goal is more clear for them. Regarding the returns, the rule of thumb is typically 2-3 times larger than what would normally be used for that size of duct. However, there has to be a bit of a balance and you do not want to make them too large. I personally stick with "the next size up" or something just under two times the size. For example, say the calculated return size is 10x10 (100 square inches). You could use a 12x12 (144 square inches) or a 14x14 (194 square inches) to increase the surface are of the return and reduce the possibility of creating air turbulence. The other thing you can do is have a decorative or "open" grate with zero filter panel on the room side, but locate the 1" filter panel a bit further down the line in a special-built airbox (which you can access, of course) to hold the panel in-line to the lead coming from the room and the lead going back to the HVAC system. This way the turbulence and possible slight whistle of a standard 1" air filter would be located away from the main room but still provide filtration to your system.

You can either use a "capture hood" with anemometer from an HVAC company (since those things are typically about $1500 each ) or just get yourself a simple handheld unit that not only measures CFM but also the exit temperature coming from the duct. Here is an example from Amazon. There is also a really nice "old school" tool called a Ductilator which will allow you to easily calculate the size duct you need for a certain volume of air (either supply or return) for rigid round, rigid square or flex duct alike. This is the exact one I have that I was able to get from my local Trane rep for free: http://www.constructionbook.com/ductulator-duct-sizing-calculator-trane-1998-d76/hvac-ducts/

But I would highly recommend (just like my previous comments) that a trained comfort adviser be hired as a consultant to work with and properly engineer your existing system to properly account for the fact that this room will be highly insulated and close to airtight with more people and electronics than is normal during peak times (Super Bowl parties, etc.). In most cases adding additional supply, a dedicated return, and mechanical dampers with a dedicated thermostat for the theater will get you close or in the "acceptable" range. The only way to have a truly perfect system for the room is to buy a dedicated HVAC system for the space which is typically not practical or affordable.

Yes, thank you. I have been trying to catch up on e-mail after being away for four days. That is closer than anything, but you are right - it is not dead on. I am going to locate a dealer for this carpet today and order one of their complementary samples. Thank you! By the way . . . I haven't found that carpet yet, but I will keep looking.

I hope this helps.
Edited by TMcG - 7/24/12 at 7:19am

If I could make a suggestion - look at the "rich" area of town and who generally does the systems for the really expensive homes. These companies are the ones that will have the most familiarity with engineering unique solutions - such as wine cellars, EVHR make-up air for 600+ CFM kitchen hood vents, temperature zoning, etc. - essentially the most complicated stuff available. If you don't know who does the HVAC for these homes then I would look toward luxury custom home builders and call their office to see who they use.

I (you) always put the supplies toward the front because you don't want the conditioned air dumping directly on the seating area which is always toward the back. Just be careful that the supply air is diverted away from the screen so it doesn't wave slightly back and forth with the air movement.

Do you have a simple sketch of this room where you can show your proposed paths for the supplies, returns, dead vents, etc? I can't seem to wrap my head around where this is going at this point without seeing a visual because of all the changes - thanks.

No quotes, but Kane is anywhere from $50 - $125 per square yard depending on the carpet type and pattern. I think the one I chose was in the $75 / yard neighborhood, excluding pad and installation.... My first priority is getting the right carpet and then negotiating the Hell out of it with a small number of vendors that will sell and install perfectly for a reasonable price. I guess we'll see on that one.

No worries. I'll help you out this time....


Now, on to more pressing matters....

• I can tell you unequivocally that one 6" supply to your theater will be insufficient
• Where are your proposed dead vent locations?
• Where are your proposed return air locations?
• One thing I hadn't mentioned explicitly before is if your current HVAC system has enough heating and cooling capacity to condition the basement and the intended first floor at the same time? That's the reasoning behind providing your HVAC guy with the brand and model number of your indoor furnace, air coil and condensing unit so this may be determined. I have a dedicated system for each floor of my house, so I knew the size of my unit was sufficient (I know, I know....that's what she said ), so all I had to focus on was properly dividing up, sizing and zoning the existing supply and returns which I hired a professional firm to engineer. I then put everything in and they inspected my work before calling the inspector for final sign-off on the work.
• I would recommend that you build your theater room shell with metal stub-outs coming into the room where your soffit will be built afterward and use this area as your dead vent / soundproofing area. Since the return will be larger, I would run in the joists of the ceiling and come down with a 90 degree elbow straight into the intended soffit area at the back of the room.

But again - check with your pro HVAC guy that you hire as they are the true experts.

Hahaha, I didn't notice the hat until after reading this.

Yeah, I'd forgive her for the Yankees cap...and even while trying to whistle Dixie while eating Graham Crackers in bed because that's just the sweet, sensitive guy I am - lol!

To explain my comment above I am posting a picture here from Moggie's build:


You'll see that he has an HVAC penetration through the shell in preparation for routing the other ducting through the perimeter soffit which he is building on top of his soundproof theater shell. This way the soffit functions as an additional layer of soundproofing for the HVAC penetration. Moggie also uses the less-common duct board which is of course much better for soundproofing that even a simple metal collar penetration.

I didn't realize your joist ran perpendicular to the room. It seems the only thing you could do is build a return air soffit in the playroom to the left and then bring it directly over through the joists at the back of the theater.

It is good to know that they sized your system for both the first floor and the basement so all you have to focus on is the dampers and zoning.

Your plan is exactly why I don't like dead vents and feel they are not necessary except when they are used as part of the forced-air HVAC system. A properly sized / zoned and dampered system will not need this supplemental in-line fan that is not tied into anything related to the main HVAC system from an electronic / control perspective. Remember, you must supply and return the same amount of air. If you have a fixed supply and suddenly are pulling 400 CFM out of the room through an in-line fan, where does the additional supply to make up for this deficit come from? It doesn't. I feel a bit like I am repeating myself with these statements regarding a properly engineered HVAC system, but I will say it one more time - a properly zoned and dampered HVAC system should have all the supply and return air you need for your room without the need for additional inline fans, dead vents for ventilation, etc. - period. Using a dead vent in conjunction with normal HVAC supply and return? Fine. Using a small in-line fan to exhaust a projector hush box into the return plenum or another room? Fine. Using a dead vent and/or an in-line fan to force ventilate a room independent of the HVAC system - NOT a good idea IMHO.