HVAC for dedicated home theater
I've met with a couple HVAC contractors to get their opinion and a quote for heating/cooling a dedicated home theater I'm about to start construction on. One has been good, but has proposed a solution that I think might be overkill and the others didn't give me enough confidence in their understanding of the issues at hand to properly handle the job.
I found this site on a quick google search and figured it would be a good place to ask for some opinions and/or some suggestions that I can present to some local HVAC contractors.
I live in Northern Ontario -- hot & humid during the summer months and cold during the winter months. The house is about 3000 sq. feet and has an existing gas furnace with adequate heating/cooling capabilities. The house also has a full HRV system. The theater I'm planning on constructing is going to reside in the basement which was partially finished when I took possession a few months ago (I have since gutted it). The room that existed where the new theater will be built had 2 6" supplies coming off two plenums and had a cold air return which was decent in size (it used the cavity between two studs - 16 o/c with a wall plate near the floor).
The theater I am about to start construction on will be a dedicated space and will have extensive sound proofing/isolation measures. The theater room will be built as tight as possible (2 layers of 5/8 drywall) with acoustical sealant on every joint. The idea is minimize the amount of noise coming in and out of the space. Adjacent to the theater will be an equipment room that will house a fairly substantial array of gear for the theater and for a distributed a/v setup for the rest of the house. This room will be built in the same fashion as the theater -- as tight as possible.
Here is a floor plan showing existing duct locations and proposed new runs:
Larger version here
My "Plan" thus far
After some extensive research and consultation with a few builders of dedicated theaters, it has been suggested that I do the following:
- Convert the existing 6" ducts (which are currently rigid) to 6" flex
- Bring the two flex ducts through the ceiling near the edge of the wall exterior wall
- build a sealed soffit around the permiter of the room (perhaps 5" tall and 12-14" deep) and box/seal out a portion of it (perhaps 3-4 feet in one direction) where the flex lines enter and install a vent on the underside of the soffit. Reason is to try and make it difficult for sound to enter/escape the room.
- Instead of tapping into the existing cold-air-return system, build a "dead-vent" instead which would simply exhaust air from the theater into an adjoining space where a regular cold-air-return would be present. More info on the design of the dead-vent can be found here: http://www.soundproofingcompany.com/...the-dead-vent/
- Install a dedicated Mitsu Mr. Slim split for cooling the space as required
- Install two vents in the ceiling of the equipment room and use an inline Panasonic fan to exhaust the warm/hot air into the adjacent hallway
- I simply want to ensure that I'm exchanging enough air in the theater space. I'm pretty confident that with the 9000 BTU Mr. Slim split that cooling won't be a problem, but I want to make sure enough fresh air makes its way into the space.
- I want to make sure its ok to use the "dead-vent" instead of tapping into the existing (and loud) cold air return system.
- I'm not sure how to bring fresh air into the equipment room.
Any suggestions or discussion would be helpful. It would allow me to point any local hvac contractors to this post with hopes of at the very least starting a discussion about the various options.
We have done a few like this and usually we just put in a Mitsubishi or Daikin Ductless heat pump that is 9-12K BTU's and thats it. If you undercut your door enough you should get fresh air into the theater since I assume you will only be using it for 2-3 hours at a time and then leaving the door open. If you are really worried about it then connect into the cold air return or install the dead vent to ensure you get a negative pressure on the room and pull fresh air in.
This is one of those KIS systems, KEEP IT SIMPLE, you don't need to over think this one. Your house already has an HRV so you are already getting fresh air into the home, as long as there is some circulation then the theater will get some too.
I personally would not add any new ducts to the new theater room because of the equipment load and the BTU's produced by the equipment you will either have an uncomfortable house and a comfortable theater or an uncomfortable theater and a comfortable house. Theaters have such widely varying loads that a dedicated system(ductless heat pump) will be best and if you add any additional ducts it will just mess up how the system works.
Do your number 4 and 5 items and be done with it.
So basically, If I leave the two existing 6" supplies and turn the furnace fan to "on", combined with a deadvent pulling air out, I should be fine. Supplement that with the Split for cooling and call it a day?
The room will be very tight -- thats my concern. The door will be completed sealed with rubber gaskets -- the point is to eliminate unwanted noise from entering/exiting the theater.
Maybe I misread, Since you were talking about building soffits I thought you meant you would have to add two vents and that the existing two vents went to the upstairs since this theater is in the basement.
Originally Posted by memmo
You can always try your theory with the two vents by turning on a portable heater in the room and then turn your furnace fan on and see how it performs since a 1,500 watt portable electric heater should put out about as much heat as theater room equipment with a couple of people in the room.
If your idea does not cool the room its time for a ductless mini split which is what I would do if its my house. The ductless is a more comfortable, more efficient long term solution.
Stick a heat pump mini split in there and run the jumper duct for return and 2 supply's like you mentioned and that should take care of varying loads in the theater room. Be sure to keep your "electronics room" cool bc all media equipment puts out a fair amount of heat and will damage if it gets too hot.
A split is definitely in the mix for cooling. I'm more concerned with air circulation -- getting fresh air in to the theater and stale air out. Also forgot to mention in my initial post that one of my concerns with the proposed solution is that since its tied in with the rest of the house, if during the winter months the house is calling for heat but the theater does not need it, it would get uncomfortable in there. Also, the system would only work if the furnace fan was set to "on" instead of "auto" - granted not a huge deal.
Originally Posted by SkyHeating
I agree with SkyHeating on this. New theater room with it owns source of heating and cooling. Simplest thing would be to put in a mini split system to control that area so you can maintain whatever temp you want without effecting your current system.
While fan on is easy to do but can lead to increased humdity throughout the home as the a/c will not be running all the time with your existing system unless you set it to do so.
Proper sized mini split system would be the most cost effective thing to do. Mini splits are very quiet when sized properly and allows the fan speed to adjust automatically for the temp. You have it set for.
I think this is the problem I'm having in general. Most of the HVAC companies I've had over only think in terms of heating and cooling. What is often forgotten (perhaps due to the fact that most are unfamiliar with a dedicated theater and it's construction methods) is that the theater room will be virtually air tight unlike every other room in the house. I agree a split is the answer to cool the space, but it doesn't address the need to have fresh air brought into the space and contaminated air exhausted.
Originally Posted by duckman06
The idea of fresh air and occupants will result is a significant moisture load. Basements do not need much cooling while critical to maintain <50%RH to avoid condensation at the cool masonary surfaces. A small whole house ducted dehumidifier is a must in a green grass climate. Suggest you check out the Ultra-Aire 75H which is ducted to/from the space and connected to the who house ducting. This will keep the whole house circulated and <50%RH even when the a/c has no cooling load and the outdoor dew points are +55^F.
Originally Posted by memmo
A second note on drywall. Best result for sound proofing a room, use two different thickness of drywall to stop varible frequencies of sound. A tip a top drywall enginerr at USG.
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"