I would skip the mini-split unless you have no other options. Either a separate zone or a dedicated unit will work. Both have pros and cons, so it becomes a matter of what fits your situation best at that point.
The contractor said to forget the mini split and thought we should go with a small seperate unit. Others have said zoning is a good option. What would the cons be to a seperate small unit (other than cost)?
Con would be, if no one is in the room for a while, and the equipment is shut down, then you are just blowing cool air into it. If you do plan on doing this, go with a thermostat that you can control either from your computer or smartphone, if you carry a droid or iPhone, or use tablet of the same.
If you have the money in your budget, I would do a separate system. I didn't have that much in my budget and went with a mini split. The theater isn't done yet so my basement HT hasn't seen a use for the AC ....BUT I have sure been enjoying the heat pump aspect of it to raise the normal ambient temp of 67 to 72! I did my install myself and bought it off eBay so expense was about $550. Thats a bunch less that a separate setup.
Cost wise I can do the seperate. I was previously unaware that systems were available for such small spaces (other than mini splits, window units, and portables). Wouldnt this be smaller than a 1 ton unit?
1 ton would be the smallest for a ductless. It is not about the loss, but also the heat gain caused by the equipment, in how much btu that it is putting out, along with factoring in how many people are in the room at any given time. You could probably compensate with the 1 ton, if you had to include say a bathroom, or a home office or such. Also have to factor in, how air tight the existing home that the home theater is going to be placed into at that time.
So overall, a 1 ton may help overall, when it comes to the existing system, in cooling the home during the Summer months. The good thing is, you could set up a zoned system, that if you know that no one will be using the space for say a week or a couple of days, you could use the new system to help the existing also.
should fullfill energy star 3.0 requirements for rooms that lack a dedicated return
Active versions improve cooling performance with an inline fan, but that fan can cause objectionable noise
Opens path for sound with adjacent room
Mini split Pros
requires very little space
low noise is a competitive feature (vs efficiency as #1 priority with forced air)
intelligent variable speed operation. System can run continuously at low speed, and ramp up with changing heat loads. Conventional units run full speed (for the most part) and adapt to varying heat loads by cycling on/off. Each cycle has a ~5min restart lock down to prevent short cycle.
Indoor unit typically sits in the theater. Possibility of vibration from deep bass?
Louder than the best forced air systems.
No option for fresh air intake
2nd zone forced air Pros
Cheaper than dedicated unit. On an already zoned system, another zone is relatively cheap. If you have buy a zone controller, install bypass ducts, etc then it's more but still likely 2nd cheapest option in this list. Capacity itself is relatively cheap (i.e. going from 3ton to 4ton unit)
Best cooling performance
Inherits options added to main unit. i.e. ERV and/or air filtration upgrades
Has provisions for fresh air intake / exhausting stale theater air to outside
When only 1 zone is active, dampers close to block off the other zone and the blocked airway introduce noise into the system
Opens a path for sound through the duct work to other rooms. The additional length the sound has to travel through the duct makes it less of a problem than dead vents.
Air handler is sized for CFM requirements of both zones active at once. Bigger fan, bigger coil, bigger compressor... all else being equal, bigger noise than would be needed by the theater alone.
2nd dedicated unit forced air Pros
Can be custom sized / engineered for theater needs. Metal is typically used in highend builds because it can be modeled. Existing tools like AutoCAD MEP can do layout, routing, connectors, etc. There are also programs that will simulate how the air flows through the ducts, problem spots for turbulence (noise), and how the air discharges & mixes with the surrounding air. Commercial units can involve further optimization like choice of fan type best suited for low noise, blade count (which affects frequency of the noise), and then engineer silencers to specifically target the frequency of the noise.
Ducts are isolated from the main system
Options can be different from the main unit, i.e. greater fresh air exchange rate for the windowless theater
If 2 dedicated units need to run at the same time, noise level of the of the units outside the theater will be louder than a zoned unit supplying both zones. That might have implications if the theater isn't well isolated from the exterior areas or if those areas are in sensitive locations (like next to a bedroom window).
Most expensive option even for basic residential with rule of thumb guidelines. Real engineering & design mentioned above is much more.
I'm not HVAC expert, but for 15 x 15 room screen you shouldn't have a lot of hot gear and dedicated HVAC may be overkill. I also wonder about 2nd zone for that size room. I don't know how big the rest of your floor is, but I would think they would have to send a lot of air through bypass and that might cool your coils down too quick (resulting in unit shutting off prematurely or freezing up if no sensor). Check with a few contractors to see what they say. Mine was reluctant to do 2nd zone for my master bed/bath due to size. I would be tempted to do a dead vent with fall back to mini split if that didn't work, but that's just my unqualified opinion.
I looked up the one Roger had and I think it was 32dB which is kind of high for theater, but the way he has his mounted I think minimizes the noise. Not sure if Rob has that much space above his theater. I think Mits has a 19dB version for in room.
Thanks for link to the Unico system in the other thread. They are redoing the HVAC in my house with some necessary structural changes, so I shouldn't need anything exotic at this point, but that outside unit being a water based chiller vs refrigerant would seem to have good DIY potential.
Thanks everyone for the great info. Far better ideas here than on the HVAC forum
Rabident, great summary and makes things far more understandable. Now I'm wondering about actual cooling needs. My last dedicated space was 2100 cubic feet but would only seat 5 people. I kept the processor, 2 amps, 2 subs, and projector in the room so it would heat up in minutes. The gear in this room will be outside of the room at the entrance in the family room cabinetry. However, there will be a projector along with a pair of PB13 Ultras and up to 6-7 people. This is why I initially thought a mini split (though ugly) would present the most flexibility. I'd assume that we'd need to install in-room returns if we decide to go the zone route. We're not zoning any of the systems other than the theater room if we decide. The house is 5000 sq ft living on single level with high ceilings but will three seperate units.
I hear you about a mini split being ugly in a nice room. Thats why mine is being hidden in a rear sofit! I didn't build a permanent sofit in the rear, instead I built a frame and am wrapping the sofit with black GOM, after I mounted the mini split. I also sprayed the mini split with flat black to help it disappear. To cover air flow I built wood grates to cover the front and bottom of the sofit at the mini split location. So far so good, (although I don't have the front wrapped yet). The beauty of mine, is that the mini split will be blowing cold air straight towards the projector.
A forum community dedicated to home theater owners and enthusiasts. Come join the discussion about home audio/video, TVs, projectors, screens, receivers, speakers, projects, DIY’s, product reviews, accessories, classifieds, and more!