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post #181 of 1236 Old 04-06-2011, 11:28 AM
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I think your system will also need to check the humidity level outside. You wouldn't want to draw that in if it's too humid.
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post #182 of 1236 Old 04-06-2011, 01:38 PM - Thread Starter
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Quote:
Originally Posted by mcascio View Post

I think your system will also need to check the humidity level outside. You wouldn't want to draw that in if it's too humid.

I agree. I have temperature and humidity sensors both indoors and outdoors that are connected to my automation panel. I can use the readings from these sensors as part of the decision to trigger an event.
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post #183 of 1236 Old 04-06-2011, 06:08 PM - Thread Starter
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Is a single 8" duct enough to feed a 19x23x7 theater? If I go with the single duct into the theater, I should be able to run the theater as its own zone using a 12" bypass. This is based on a couple of the calculators I used. I would still want to do some more accurate calculations before making a final decision.

Reading through the documentation, the other thing I need to decide is where to dump the excess air from the bypass. Ideally I would dump the air from the bypass directly into the cold air return, but a 12" duct is really big and would take up a lot of headroom. The only other option is to release the air into a "dump zone" like the storage area or workroom.
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post #184 of 1236 Old 04-07-2011, 03:41 AM
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The duct size is dependent on the cfm required and the velocity of the air flow. You've given the size of the room, which can be used to determine CFM.

How many tons is your ac unit?

How many people will the theater accommodate, and will the equipment be in the room or outside the room?

With that info I can check the duct size.

Dumping cold air into a room that doesn't need it is not a great idea. Cooling of a room is supposed to be designed in accordance with the standard, so it's technically a violation. Dumping cold air in a room that isn't insulated (not sure if yours is or not) would also be a violation.

From a practical standpoint, the room is probably going to get real cold and moisture is going to condense since you would presumably be dumping way more cfm in there than is needed. My suggestion is to do the bypass. Perhaps you can do 2 smaller bypasses to give you the same free area as one large duct?
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post #185 of 1236 Old 04-07-2011, 04:03 AM - Thread Starter
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Thanks for the response Tim.

Quote:
How many tons is your ac unit?
The AC unit is 5 tons.

Quote:
How many people will the theater accommodate
I plan to have 8 seats in the theater. Will probably have 4 people 90% of the time.

Quote:
will the equipment be in the room or outside the room?
The equipment will be inside the room.

I really would prefer bypassing the excess air into the cold air return. One of the risks is that a large amount of cold air dumping back into the return can cause the air handler to get too cold. Obviously, with only one duct being fed on this zone, a majority of the cold air will be returned into the system. One solution i have read about is to set all dampers to remain open 5% to release some of the excess pressure into the other zones, but not enough to change the temperature in those rooms by more than 1 degree. I need to investigate this further.

The other item that has me very concerned is the reliability of the dampers. almost half of them would be in an area I am planning to drywall. That would be a major issue if one (or more) ever stop working.
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post #186 of 1236 Old 04-07-2011, 06:30 AM
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Rough numbers.. There is more to it if you want an exact answer.. So I will make some assumptions.

19x23=437 sf

Guess cooling load at 2 btu/sf = 872 btu

6 people at 600 btu/person = 3600 btu

Guess 30A total electronic equipment in room = 3600W

3600W x 3.4 btu/w = 12240 btu

Total load = 16712 btu

Guess delta-T 20, 773 CFM required.


Guess 800fpm velocity, .1 fr, 50' length

-14" duct

Kinda rusty on this stuff, but I believe I did the right calcs based on my guesses. I would bet money the cooling load is oversized; you probably don't have 30A of electronic equipment and can probably cool for less than 2 btu/sf (would depend on how much the foundation sticks out of the ground, your location in the US, which way the wall face, etc).

EDIT: just for kicks, I figured the load without any equipment and it came out at a 7" duct. I am cooling my theater with (1) 6" run, but there is no equipment in the room, 8 people. I did have that calculated by computer.
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post #187 of 1236 Old 04-07-2011, 06:56 AM - Thread Starter
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Thanks Tim. This great info. Another idea I had was to build a rectangular duct to supply air to the theater. I am guessing it would be around 8"x10". This would allow me to stick with one duct which could provide plenty of air flow to the theater.

I had a few minutes earlier this morning, so I gave Aprilaire a quick call (one of the zone controllers I am considering). They confirmed that two smaller bypass ducts would work as well. He said that a single 12" bypass duct could handle the load of a 5 ton system. Running two 6" bypass ducts would be the equivalent. This would allow me to run the bypass ducts between the joists which would be preferable.

He also pointed out that better zone controllers will include a plenum temperature probe which has a hi/low cutoff to prevent damage to the air handler. He highly recommended installing one in my system.

Lastly, he pointed out that if I every upgrade to a system with a variable speed fan, the bypass would need to be adjusted, or even removed. He said they are much better at managing air flow. I hope I won't be upgrading my system any time soon, but this is good to know.

I still need to look into the reliability of the dampers. Most of them have replaceable motors, but it is still a matter of access to the dampers.
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post #188 of 1236 Old 04-07-2011, 07:26 AM
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Nick,

That's one of the reasons I chose the Arzel system. They had 2" x 12" Regidampers that allowed me to put them right at my registers on the main floor. I was looking at another vendor and they didn't have that size. So you may check with your register sizes and see if they have what you need. The cost goes up almost double getting a register damper as opposed to their inline ones.
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post #189 of 1236 Old 04-07-2011, 08:00 AM - Thread Starter
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I saw those dampers on their site. Unfortunately, it looks like Arzel will not allow for self install. It appears that they use an air driven system that requires a compressor that can both add and release air to move the damper. This adds to the complexity factor for self install. A couple of places I spoke with sell and support this type of system, but acknowledged the complexity they add due to the additional equipment.

Aprilaire also sells a system similar to Arzel that will bring in outside air based on different rules. I may take a look at this system in place of a fan drawing air through a duct. The Aprilaire and Arzel system use rules to mix the air and make sure it isn't too cool, humid, etc.
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post #190 of 1236 Old 04-08-2011, 02:15 PM - Thread Starter
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OK, I decided I needed to make some decisions and get this project back on track. I was considering multiple options, but I really wanted to find a way to make the zoned system work for me. I stayed up late last night reading through all of the documentation on the various zone controllers and all of the accessories. I also mapped out all of the ducts and potential zones. Finally, I called each of the 3 manufacturers I was considering this afternoon to finalized some of the details around my plan.

I originally was looking at Arzel, RCS and Aprilaire. There are others out there, but these 3 seemed to closely match what I was looking for. Here is what I looked at:
  • Arzel - Unfortunately, Arzel does not support a self install option and won't sell to individuals. They have some really nice products, but I really wanted to go the DIY route, so that ruled them out.
  • RCS - RCS seems to have some nice products, but there wasn't as much documentation, I couldn't get a live person on the phone who could answer any of my questions and they didn't offer some of the features that the other 2 did.
  • Aprilaire - Aprilaire offers 4 levels of panels, and many accessories/options. I found their list of available options to be similar to Arzel. When I called their tech support line (I actually called 3 times) they seemed happy to help me out and sent me lots of documentation via email. They then walked me through a lot of the calculations and helped me decide the best way to setup my system. This combined with the fact that I could purchase their equipment at a very reasonable price through one of the home automation distributors I have worked with in the past helped me make my final decision to go with Aprilare.

I have decided to break my home up into 4 zones:
  1. 2nd floor
  2. First floor
  3. Basement
  4. Theater

Here is the equipment I selected:
  • Aprilaire 6404 zone controller. Can control 2 to 4 zones (expandable to 12). Lots of great features including a plenum temp sensor to prevent overheating/freezing of coil if air flow isn't set right. The unit also prioritizes all 4 zones based on temps, humidity, amount of time zone has been running, heat vs. cool, etc.
  • Aprilaire 8028 Power distribution panel. This adds additional power for controlling dampers. Main panel can hold up to 6 dampers closed at one time, but because I am putting a damper on each duct, I need to be able to close more while sending heat/cooling to just the theater zone.
  • Aprilaire 6706 retrofit ducts. I purchased 21 of these. I like these for two reasons: (1) They can be installed by simply cutting a slot in a rigid duct. (2) They do not use any gears which is the part that typically breaks on a damper.
  • 24v Power supply - purchase one that is in a cabinet and has 4 fused outputs.
  • HAI Omnistat RC 2000. I plan to control the temps for all 4 zones through my HAI OmniPro II. I currently have one of the older Omnistat thermostats, but they now have a newer model with more features. The existing one and the new one will control the 1st and second floors. I will temporarily use 2 inexpensive non controlled thermostats for the basement and theater until those rooms are complete.

I still need to purchase my bypass damper and one more damper for the theater, but I wanted to walk through my calculations one more time before making the final decision on those items. I really don't want to mess up my calculations on the bypass damper and I need to determine the size of the theater duct. I have a lot of work ahead of me, but zoning the HVAC has been something I have thought about for years. I also think that I will be much happier with the theater being able to control the temperatures much better.
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post #191 of 1236 Old 04-09-2011, 04:56 AM
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equivalent rectangular duct sizes are 10x13 or 12x11
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post #192 of 1236 Old 04-09-2011, 05:09 AM - Thread Starter
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Quote:
Originally Posted by Mr.Tim View Post

equivalent rectangular duct sizes are 10x13 or 12x11

Thanks Tim, I think that 12x11 may be what I shoot for. I was also looking to see if there is an easy way to run two smaller supply ducts (maybe 8" each) into the theater, but I don't think there is. The big issue is that the joists in the main part of the basement don't align with the joists in the theater (16" OC in the main basement vs 12" OC in the theater) plus the theater ceiling is about 6" lower, so it is going to be a real challenge feeding a duct into the theater above the beam.

Does anyone know where I would buy duct board? Do they sell it at Home Depot or Lowes?
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post #193 of 1236 Old 04-09-2011, 05:33 AM
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8" round would handle about 250 cfm, so you would need at least 3 runs.

(2) 8x10 rectangular would get you the cfm you need.

If I have the layout correct, I think you pretty much have to have the registers (and therefore duct) in the same joist bay, otherwise they won't be lined up.

Another option might be (3) registers, a left & right in one bay, and a center register in another bay. Might even follow your proscenium.

When you decide which way you're going to go, we can figure out what size registers you need to keep the noise down.

The only other option would be to exhaust the equipment heat out of the room. The heat generated by the equipment is really what is driving the duct size up.
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post #194 of 1236 Old 04-09-2011, 05:39 AM - Thread Starter
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Quote:


The only other option would be to exhaust the equipment heat out of the room. The heat generated by the equipment is really what is driving the duct size up.

I am considering drawing air out above the equipment rack with a thermostat controlled fan and venting it outside. My biggest concern would be the noise of the fan as well as sound escaping in that corner. I know there are some very quiet fans made, so I will look into those. Can I use a fan to pull hot air from the equipment rack into the cold air return to help force it out of the room, or is this not a good idea?
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post #195 of 1236 Old 04-09-2011, 05:50 AM
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You could, but if the hvac isn't running it probably won't work well. The heat will probably be pushed out of the nearest return register.

I'm not an expert, but I personally would be considering pushing it directly outside.

The consequence is that you are now pulling the cool air from the supply registers (which are recommended to be-- and I assume you planned on placing them-- in the front of the room). This would be counter productive, as you should be trying to draw the cool air towards the return registers in the rear of the room.

A possible solution.. which could turn out to be pretty interesting.. Is to place a supply duct in the equipment enclosure, to supply cool air only to the equipment.

One thing we could hammer out is exactly how much heat the equipment will produce. I figured 30A which would be (2) 20A circuits at their max nominal rating.

If you know exactly what equipment you will have, we can figure out exactly how much cooling you need. In actuality you could be using half of that.
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post #196 of 1236 Old 04-09-2011, 05:51 AM
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post #197 of 1236 Old 04-09-2011, 07:45 AM - Thread Starter
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Quote:


The consequence is that you are now pulling the cool air from the supply registers (which are recommended to be-- and I assume you planned on placing them-- in the front of the room). This would be counter productive, as you should be trying to draw the cool air towards the return registers in the rear of the room.

My supply registers will be in the front of the theater and the returns in the rear. My equipment rack will also be in the back corner of the theater. I may have had an earlier drawing showing the rack in the front, but after talking with bpape, he suggested I move it to the rear corner.

My preferred method would be to exhaust hot air to the outside, but this will be dependent on not compromising the sound control.
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post #198 of 1236 Old 04-09-2011, 08:56 AM
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Ah.. I must have been looking at an old drawing.

Either way, figure out how many watts or amps each piece of equipment uses and maybe we can get some better numbers.

Is the room below grade on all sides? How much sticks out of the ground?
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post #199 of 1236 Old 04-09-2011, 02:58 PM - Thread Starter
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I kept changing things around, so I finally decided to hold off on posting another design until I was sure of the changes. At this point, I think it is pretty safe to do that. I just need to find the time to work on it .

I really don't know what equipment I am going to buy yet, so that is really a guess at this point. The theater is completely below grade with the exception of about the top 10-12 inches.
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post #200 of 1236 Old 04-09-2011, 03:14 PM - Thread Starter
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So, I decided to go ahead and do the rough in for the sub panel (at least run the wire to the location). The sub panel will be mounted inside the sealed theater, but I want to at least get the wire run. I stopped by the township office to ask some questions about my electric plan before finalizing it. I discovered a couple of things have changed since I last ran a sub panel several years ago.
  1. If the panel is over 50 feet from the main panel, you must run a second ground outside of the building. That means I will need to drill through the wall and drive a grounding rod no more than 8 feet from the wall.

  2. The real shock was the price of wire. I knew copper had gone up, but I hadn't bought anything larger than 12 gauge in years. I called around on Friday and was told by the local wholesaler that they no longer carry 6/3 copper since all surrounding cities now allow aluminum wire. I would have to drive an hour away to get it from one of their other warehouses and it would be $7.44 a foot . I don't know if he was just trying to scare me away or what. Even if it was half the price, I was facing the fact that I would have to run 4 gauge aluminum for the sub panel. It was $125 for 75 feet of 4 gauge aluminium.

While I was digesting all of this, I decided to stop by Home Depot to look at conduit and and other supplies. I decided to check on their price of aluminium wire while I was there. They wanted $3.27 a foot for aluminum. That would be $245. As I was looking around I noticed that they had some pre-packaged 6/3 copper wire sitting on the shelf. I was pleasantly surprised to find out that it was $150 for 75 feet. I thought for $25 more than the wholesaler wanted for the aluminum, I would just get the copper (plus save another hour of time driving there and back).

I want to try to get this wire run before my HVAC supplies come in.
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post #201 of 1236 Old 04-10-2011, 01:57 PM
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Quote:
Originally Posted by NGiovas View Post

My supply registers will be in the front of the theater and the returns in the rear. My equipment rack will also be in the back corner of the theater. I may have had an earlier drawing showing the rack in the front, but after talking with bpape, he suggested I move it to the rear corner.

My preferred method would be to exhaust hot air to the outside, but this will be dependent on not compromising the sound control.

Nick,

Based on your last drawing, and the way you are describing venting to outside, I am assuming you are putting the equipment closet in the right rear (upper-right corner). The problem I see of pushing air outside, is you need to replace that displaced air in the house. Without using an external supply, you must draw that air from other cracks, crevices, furnace makeup-air duct, etc. If you can move slide your entry door towards the front row to give space in the back left corner, you could then draw air from the basement into the closet and expel it back out into the basement. To reduce noise leakage, use the stud wall cavity to create a baffle (or maze) for the air to follow through the wall, instead of having the opening go straight through the wall. Yes, this might compromise the noise confinement more than the other corner, but it keeps the design very simple. Optionally, if you have the room to install 2 duct runs from the right rear corner back to the basement, you could do the same concept up there. However, you will be pushing/pulling the air much further, which could require a larger fan/motor.

Another advantage I see of the rear left corner, is the equipment is immediately accessible as soon as you enter the room, without having to rely on a remote for everything, or crossing the entire width of the room to manually set something.

As for quiet fans, I am using a Broan inline (Grainger part #4TR54), which are relatively quiet "squirrel cage" designs. Is is mounted in a soffit/bulkhead outside the theater, packed in batt insulation. This is a 300CFM fan for an 8" duct. I split the incoming line into two 6" ducts, and use one to cool my CRT PJ, and the second to draw air out of the equipment closet. Grainger is a good supplier of all kinds of fun things. For Broan Inline models, look here. Options run from 100CFM all the way up to 1500CFM. Prices look to be about 50% more than they were 8 years ago, but such is life, as you noticed with the copper wire.

Geordon
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post #202 of 1236 Old 04-10-2011, 04:56 PM
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Quote:
Originally Posted by NGiovas View Post

If the panel is over 50 feet from the main panel, you must run a second ground outside of the building. That means I will need to drill through the wall and drive a grounding rod no more than 8 feet from the wall.

I have never seen a grounding electrode required at a subpanel unless it is in a separate building.

I don't think it would hurt, but I'd like to know how they are coming up with that.

Is there a local amendment to the NEC?

6/3 NM is now limited to 55A (used to be 60A back in the day), just in case you weren't aware of the change.

Tim
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post #203 of 1236 Old 04-10-2011, 05:29 PM - Thread Starter
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Thanks for the feedback Geordon and Tim. This is very helpful.

To make sure we are all talking about the same thing, I thought it would be a good idea to update my drawing to the latest version. This is just the theater area for now (the other areas have not changed anyway). Since the room is framed, these are the final dimensions.



The rack will be built once the room is drywalled. My plan is to bring the HVAC in at the very front of the room and have the cold air return in the back.
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post #204 of 1236 Old 04-10-2011, 05:35 PM
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Can you do a sealed door to the equipment and circulate air from the equipment space to the rest of the basement?

I think even a glass door with a silicon weatherstrip would work fine.

If you can get that heat out of the theater, your ductwork will be that much easier. The room will also be that much quieter. Geordon has some good ideas.
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post #205 of 1236 Old 04-10-2011, 05:36 PM - Thread Starter
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Quote:


I have never seen a grounding electrode required at a subpanel unless it is in a separate building.

I know it wasn't required when I installed the sub-panel in my garage/shop. He said that in some communities they require 2 rods no further than 8' apart. I don't understand this since it still has the isolated ground that runs to the main panel.

Quote:


6/3 NM is now limited to 55A (used to be 60A back in the day), just in case you weren't aware of the change.

Thanks. I am planning to run a 50 amp breaker, which is probably overkill, but I own the breaker, so I thought I would reuse it. The panel has 8 slots which will be more than enough for the theater. My main goal was to only run one wire into the theater and then run everything else inside the sealed drywall.
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post #206 of 1236 Old 04-10-2011, 05:39 PM - Thread Starter
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Quote:
Originally Posted by Mr.Tim View Post

Can you do a sealed door to the equipment and circulate air from the equipment space to the rest of the basement?

I think even a glass door with a silicon weatherstrip would work fine.

If you can get that heat out of the theater, your ductwork will be that much easier. The room will also be that much quieter. Geordon has some good ideas.

I hadn't thought of that, but that sounds like a great idea. I am going to have to look into this.
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post #207 of 1236 Old 04-10-2011, 05:45 PM - Thread Starter
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Quote:
Originally Posted by Geordon View Post

Nick,

Based on your last drawing, and the way you are describing venting to outside, I am assuming you are putting the equipment closet in the right rear (upper-right corner). The problem I see of pushing air outside, is you need to replace that displaced air in the house. Without using an external supply, you must draw that air from other cracks, crevices, furnace makeup-air duct, etc. If you can move slide your entry door towards the front row to give space in the back left corner, you could then draw air from the basement into the closet and expel it back out into the basement. To reduce noise leakage, use the stud wall cavity to create a baffle (or maze) for the air to follow through the wall, instead of having the opening go straight through the wall. Yes, this might compromise the noise confinement more than the other corner, but it keeps the design very simple. Optionally, if you have the room to install 2 duct runs from the right rear corner back to the basement, you could do the same concept up there. However, you will be pushing/pulling the air much further, which could require a larger fan/motor.

Another advantage I see of the rear left corner, is the equipment is immediately accessible as soon as you enter the room, without having to rely on a remote for everything, or crossing the entire width of the room to manually set something.

As for quiet fans, I am using a Broan inline (Grainger part #4TR54), which are relatively quiet "squirrel cage" designs. Is is mounted in a soffit/bulkhead outside the theater, packed in batt insulation. This is a 300CFM fan for an 8" duct. I split the incoming line into two 6" ducts, and use one to cool my CRT PJ, and the second to draw air out of the equipment closet. Grainger is a good supplier of all kinds of fun things. For Broan Inline models, look here. Options run from 100CFM all the way up to 1500CFM. Prices look to be about 50% more than they were 8 years ago, but such is life, as you noticed with the copper wire.

Geordon

I don't know what kind of potential issues this would created, but since the door is now up front and the riser will cover the full width of the room, I wonder if I could pull air into the bottom of the rack from a duct running under the riser along the back wall. It could enter the theater through a dead vent on the outside of the wall.
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post #208 of 1236 Old 04-11-2011, 06:31 AM
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Originally Posted by NGiovas View Post

I know it wasn't required when I installed the sub-panel in my garage/shop. He said that in some communities they require 2 rods no further than 8' apart. I don't understand this since it still has the isolated ground that runs to the main panel.

Maybe there are some local amendments. Per the NEC a separate grounding electrode would only be required in a separate building. The grounding rods are required to be installed below permanent moisture level, but at least 8' deep (so if you have an 8' rod, it should be flush or below grade).

The minimum separation for ground rods is 6'; there is no maximum separation.

Two rods are required unless you can prove 1 rod has less than 25 ohm resistance. Since the meter to measure resistance is so expensive, most people just put in 2 rods. In some cases you don't even need rods if you are bonded to other types of grounding electrodes.

Your thinking is correct in that why would you install another electrode when you have a grounding conductor from the main panel.

Sometimes it's just easier to go with the flow, but me being the stubborn SOB I am, I would be asking where they are getting these requirements from I wouldn't recommend it, though
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post #209 of 1236 Old 04-11-2011, 06:37 AM
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Originally Posted by Mr.Tim View Post

Can you do a sealed door to the equipment and circulate air from the equipment space to the rest of the basement?

I think even a glass door with a silicon weatherstrip would work fine.

If you can get that heat out of the theater, your ductwork will be that much easier. The room will also be that much quieter. Geordon has some good ideas.

That is exactly what I did. I had a piece of smoked 1/4" glass custom cut for the my equipment closet door on the inside of the theater, and use a magnetic catch to draw it tight against the weather stripping. My closet is on the back wall, but I have the advantage of having the actual space framed outside the HT, with an exterior weather-stripped door on the backside for full access to the rear of all the equipment. Makes for very easy maintenance. I don't hear anything from the closet, but then, again, there are no fans on my equipment, now that the HTPC sits in pieces on the floor, being replaced years ago by my HD-DVD and Blu-ray players.
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post #210 of 1236 Old 04-11-2011, 06:43 AM
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Originally Posted by NGiovas View Post

I don't know what kind of potential issues this would created, but since the door is now up front and the riser will cover the full width of the room, I wonder if I could pull air into the bottom of the rack from a duct running under the riser along the back wall. It could enter the theater through a dead vent on the outside of the wall.

That sounds like it might work, if your supply and exhaust can be separated enough that you aren't sucking the warmed exhausted air right back into the closet.
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