Finally finalized all the HVAC plans today. I only exchanged 153 emails with the HVAC engineer and equipment guy over the last 24 hours to nail this down. :-) The HVAC engineer ran all the necessary Manual J & D load calculations and we came up with the following. Why do I always feel like I overdo things? Thank the Lord I didn't buy the Sony projector.
These were the general requirements:
1. Chief concern is sound going through the duct to areas outside the theater and sound coming into the theater through the outside unit. Target noise level of NC22 or less with the system fully operational - so decouple/isolate the HVAC system itself. Use of nylon duct straps is recommended.
2. Flex duct should transition to a double-sided rigid collar when making penetrations through the soundproof shell and then transition back to flex, if appropriate, bar diffusers FPM of less than 250 will be dictated by the size of the bar diffuser used. For a standard 6" flex duct, 4" x 24" bar diffusers will be adequate, (less than 250 fpm), oversized return air duct to reduce air turbulence. To keep diffusers from creating a lot of air flow noise, it’s critical we do not have more than 250 FPM through a slotted or bar type diffuser.
3. 6 air changes per hour and 15 cfm of fresh air per person. Seating for 7 people.
4. RH between 40-50%.
5. Ability to cool the room in the winter. Normal thermal loss calculations don't apply to home theaters that are sealed up tightly. Take into account lighting, people and projector heat loads
6. Returns are high mounted (ceiling) and to the rear of the room Would recommend outside corners, not directly behind the seating. Noise transmission in the returns should never exceed the noise from the supplies and the system must be designed this way. Supplies are in the front of the room, high mounted (ceiling) and not near the screen. Or if placed near the screen they should have a 15 degree angle to divert air flow away from the screen. Diffusers should be Lenticular, slotted or bar type pointed away from seating areas to avoid drafts. Keep dampers as far away from registers as possible.
7. Adequate heating/cooling for equipment room area.
8. Home theater thermostat will be located in the equipment room so we will need to utilize a wired remote sensor.
Spec'd the following equipment:
The Carrier Infinity system gives a lot of control over air flow, temp and humidity and since both the furnace and AC unit are both dual stage I can utilize the low stage for air flow into the theater room.
Three zones - 1. Theater 2. Upstairs 3. Room above garage
Carrier Infinity two stage AC unit - quiet, better dehumidification and low flow will allow me to keep noise to a minimum at the required 250 FPM
Carrier Infinity multi-stage, variable speed blower 96% furnace - quiet and variable speed fan is desirable for the theater to minimize noise
Infinity zone system
Carrier steam humidifier - works with Infinity system so temp and humidity can be controlled with a touch of a button
Pre-plumbed for an ERV to install later - dedicated for theater if I can't get the air exchanges I need
Exhaust fan and thermostat for equipment room
Bar diffusers for supplies and returns