Motorized damper + home theater help!?!

**memmo** · 08-01-2013, 09:04 AM

Hello folks,

So I'm building a dedicated home theater in the basement that will be very tight (for sound isolation). I'm having a mechanical engineer do the calculations now for cfm/velocity etc, but the ideal plan goes something like this:

Two 6" supplies feeding the theater (from one of two main trunks in the house).
One 6" exhaust. Since I didn't want to tie into the existing system (for noise reasons), my designer has suggested a technique where we'll use an inline Panasonic Whisper Series exhaust fan (up to 240 cfm) up in ceiling of the hallway just outside the theater. It'll pull air from a ceiling "return" in the rear ceiling of the theatre dumping it out into a hallway/common area where it'll get picked up by the regular cold air return and recycled.
Furnace fan set to "on" while we're in the theatre to circulate air.

What I'd like to accomplish:

I'd like to install motorized dampers on the two 6" supplies for two reasons. First, I'd like to be able to close off one of the dampers when the theater is empty, diverting air to the rest of the house. Secondly (and more importantly), I'd love to be able to have the one or both of the dampers close if during winter months the house calls for heat but the theater space is already too warm.
I'd like to have an easy way to turn on the Pansonic in-line ceiling fan (the one that will exhaust the room) when we're in the room.

I have no idea how this could be wired. I assume I need the two dampers themselves, a controller to control them, and tstat for the theatre. How all this would be wired is beyond me - especially if it has to tie into my existing tstat (in order to know when the heat cycle is on). I'd be happy to pay for some assistance if anyone wants to PM me cuz I'm lost!

**beenthere** · 08-01-2013, 05:46 PM

Regular members don't have PM ability.

**memmo** · 08-01-2013, 10:47 PM

Oh I see. Well if anyone cares to help, respond in this thread and I'll post my email address.

**ryan1088** · 08-01-2013, 10:58 PM

How about something far less complicated to install, like a dedicated ductless mini split you could turn on just before you want to use the space? Also make sure your engineer takes into account the heat load for however many people are going to be in there, in addition to adding some fresh air to keep co2 levels down.

**memmo** · 08-01-2013, 11:12 PM

I plan on roughing in a ductless split so I have the option of easily adding one later if needed, but it does nothing to address my main concern of bringing in fresh air and exhausting stale air.

I suppose I could handle both the supply and return by exchanging air with the room next to the theatre but that complicates things from a sound isolation standpoint and requires a split and two in-line fans from day one.

**ryan1088** · 08-01-2013, 11:16 PM

You could do a small ERU/ERV unit that would exchange the air and temper the fresh air coming in.

**memmo** · 08-01-2013, 11:24 PM

I thought about this too as it would be ideal, but without moving a main trunk and/or adding soffits into the theater space (which is only 7'6" in height) there is no way for me to get ducts into the space

**beenthere** · 08-02-2013, 05:20 AM

Originally Posted by memmo

Oh I see. Well if anyone cares to help, respond in this thread and I'll post my email address.

Email addresses are not allowed in pot. You may put it in your profile.

**ckartson** · 08-02-2013, 06:13 AM

Many of the ductless minisplits do have a duct connection for OA. Some have a four inch round connection. The theater room would be in a slight positive pressure while the unit is on. As far as controlling dampers for this space it would be a no brainer for a good tech.
Occupancy switch, Auto changover heat cool stat and a couple of relays would probably do the job. The problem I see with the sequence you are asking for is what if the theatre is full (people) and you need cooling but the homes t/stat is not calling? Still think a mini is your best bet.

**memmo** · 08-02-2013, 06:37 AM

Originally Posted by ckartson

Many of the ductless minisplits do have a duct connection for OA. Some have a four inch round connection. The theater room would be in a slight positive pressure while the unit is on. As far as controlling dampers for this space it would be a no brainer for a good tech.
Occupancy switch, Auto changover heat cool stat and a couple of relays would probably do the job. The problem I see with the sequence you are asking for is what if the theatre is full (people) and you need cooling but the homes t/stat is not calling? Still think a mini is your best bet.

I do believe at some point a ductless split will be apart of the equation for just the reason you suggested. Like I mentioned, I plan on roughing it in and just purchasing it later (I'll probably go with a 9,000 BTU Mitsubishi Mr. Slim as they're very quiet). The factors for delaying the purchase are:

1. Budget - if I can rough in and purchase later (next spring/summer) it helps.
2. 90% of the time it'll be my wife and I alone in the theatre. No other heat sources are in the space (other than lights which will be off most of the time). The projector will sit in an adjacent room and fire through the wall.

**ckartson** · 08-02-2013, 06:47 AM

The cost of dampers, the exhaust fan, stat, relays, labor, probably isn't far from the mini split. Why not just wait until you can afford the equipment?

**ckartson** · 08-02-2013, 06:50 AM

The cost of dampers, the exhaust fan, stat, relays, labor, probably isn't far from the mini split. Why not just wait until you can afford the equipment? I still feel your sequence has a lot to be desired when the homes system is not on but your theater is demanding heat or cool. just my two cents.

**memmo** · 08-02-2013, 11:33 AM

Like I said though (unless I'm not understanding something) is that I'll still need the dampers/fans etc. The split won't magically exhaust the space nor will it heat the space when its -30c outside. It also won't address the fresh air aspect.

So if i've got to do everything first, why not do what is needed first and then add on a split if I find that I need additional cooling later?

**JDenyer232** · 08-02-2013, 12:19 PM

Originally Posted by memmo

The split won't magically exhaust the space nor will it heat the space when its -30c outside.

They make mini split heat pumps. I think you are over complicating this. A ductless minisplit heat pump and a small ERV are all you need.

**Mike19** · 08-02-2013, 12:35 PM

My boss has a home theater in his basement. It cools with a mini-split and has electric baseboard heat. Also has a small erv. Seems to work pretty good. His seats quite a few people and has an outside area with mini concession area with keg cooler, popcorn machine etc... If memory serves erv feeds supply air in behind mini-split, and pulls exhaust air out from concession area and bathrooms.

Feeding it off the house furnace/ac and putting in dampers and a small exhaust fan may or may not work. Installing and wiring it should be pretty straightforward for a good technician.

You could always save the expense of buying dampers and wiring it by just having the ductwork installed and put a manual dampers in the main line that feeds them, open it when you use the theater, close it when you're done, see if that is enough to keep the theater comfortable. If that works then buy dampers and have your control system installed. If it doesn't work so great you're only out the cost of some ductwork.

How big is the theater and how may does it seat? May help to put things in perspective.

**ckartson** · 08-02-2013, 02:14 PM

You definitely are not understanding something. Minisplits come as heat pumps, which is what I assume you would be putting in. Outside air connection would give you OA. Positive pressure in the space would give you ventilation in the space. You were planning on dumping the exhaust air into the hallway outside of your theater so I was assuming that your house was not so tight that 5 or 10 cfm of OA would leak out of the house no problem. With having a separate unit you would have no need for the extra ductwork. Maybe a transfer air grill in the ceiling to get the 5 to 10 cfm of OA out to the hall and that's about all you would need. There is no magic to it. It's been done. You are saying exhaust, I am saying positive pressure.

**CJW-PIC** · 08-02-2013, 03:20 PM

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**Shophound** · 08-02-2013, 03:43 PM

Originally Posted by memmo

Like I said though (unless I'm not understanding something) is that I'll still need the dampers/fans etc. The split won't magically exhaust the space nor will it heat the space when its -30c outside. It also won't address the fresh air aspect.

So if i've got to do everything first, why not do what is needed first and then add on a split if I find that I need additional cooling later?

As ckarston noted, you may be missing the fact that a mini-split can heat as well as cool. It can also bring in fresh air. You will just need a way for air to leave the space so there is a turnover of fresh air. That can be accomplished via an exhaust fan.

I don't know what size your theater is, or where it will be located in the house, or how you plan to light it. Two people plus incandescent bulbs in a home theater could get a bit warm in summer between run times of your house a/c system. The motorized dampers are essentially zoning, but it's difficult to do residential zoning well with DX (direct expansion) a/c equipment. It can be done, but often with klunky compromises like bypass ducts or dump zones.

The mini-split will ultimately be your best choice for the theater...I suggest you re-evaluate your budget and find some way to work it in. As another poster suggested, you may be near even on cost between what your designer has proposed and what is being discussed here as an alternative.

**jpsmith1cm** · 08-02-2013, 08:16 PM

CJW-PIC

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**memmo** · 08-03-2013, 09:13 PM

Thanks guys, a lot of food for thought. I've attached a drawing showing the situation I'm dealing with. I can't think of anyway to make an ERV work (ducting wise). I have the following issues:

1. Steel beam separating the theatre space from the rest of the basement.

2. On the left side of the house, joists run left to right. On the right side of the center beam and in the rear of the house, joists run in the opposite direction meaning it's impossible to get any ducting from the mechanical room over to the theatre without dropping down below the steel beam. And since i'm dealing with only 7'6" of headroom (less to the bottom of the beam), this is not really a suitable option.

3. In the rear of the theater (bottom half of the room), there is only 1 remaining open joist cavity. All the others are consumed by either ducts going upstairs or cold air return panning (for a return in the living room directly above the theater).

Large version here.