Mini Split / ERV? - HVAC advice - AVS Forum
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post #1 of 20 Old 05-22-2013, 03:58 PM - Thread Starter
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Hello,

Doing a dedicated theater in a former "media room" version of a third garage bay (builder option). The room is about 12 x 20 x 9, and was tied to the 1st floor ac. I have 18" of space between the 1st and 2nd floor where the current duct is ran. It is a straight shot accross the 2 car garage to the side of the house my pool equipment is on.

Most of the advice I got was to go with a mini split rather than trying to use / soundproof the existing ducting, and I have decided to go that way, but I could use some more advice.

It looks like the mini splits are made for high wall mount or can be hidden in the ceiling. I know I am going to need to introduce fresh air into the room as I am doing the clips/channel/dd/gg treatment. I have heard there are fresh air options on the newer mini splits (ducted mini splits), and I have heard that it can be done other ways. Right now the room is stripped and I need to decide / install before going any further.

What mini splits are recommended, and is it best to get one with fresh air, or introduce fresh air another way?


Any help is greatly appreciated!!

Pat
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post #2 of 20 Old 05-23-2013, 03:09 PM - Thread Starter
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Bump. Can anyone with a mini split share how they get fresh air into the room?

Thanks
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post #3 of 20 Old 05-23-2013, 07:39 PM
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ceiling mounted minisplits usually have fresh air intakes. Do a google search for ceiling cassette mini split.

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post #4 of 20 Old 05-23-2013, 11:08 PM - Thread Starter
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I have found a couple. Just wanted to get feedback from anyone actually exchanging air this way, versus some other method (dead vent, opening a door every time someone passes out, etc)...
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post #5 of 20 Old 05-24-2013, 08:18 PM - Thread Starter
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Is anyone using a mini split with fresh air capability?... or using a mini split and bringing fresh air in some other way?
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post #6 of 20 Old 05-24-2013, 08:29 PM
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My minisplit does NOT have fresh air in. I purposely ran 2 6" flex ducts in and out of the theater for fresh air. With several bends in the run, I am planning on placing a hydroponics fan in my utility room (where the flex duct is routed) and it will be triggered to a thermostat placed in the top of my rack. When the rack starts to heat up the thermostat will kick on the fan in the other room and draw air from the theater..through the bottom of my rack.and out the top..... and out the equalized pressure will bring fresh air in using the other duct. If the pressure difference doesn't do it, I will just get a second hydroponics fan and place it on the other flex duct.

So far fresh air isn't a problem. We never are shut up in the theater more than a 2 hour movie and most the time someone has to go to the restroom during the movie. Door gets opened and fresh air enters room. We do, however, only have 4 people max in the theater right now. When the room is filled, the fresh air might be a larger concern as well as my "invented" rack cooling / fresh air solution.

On a related topic, my theater is in the basement and we haven't run the AC yet, but the heater in the minisplit is on every time! Our basement is not heated unless we are planning on being down there and so the theater (and rest of the basement) stays about 65 degrees or so. But I assume that it the room started out at 70-72, a room full of folks would have me flipping on the AC pretty quickly!!
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post #7 of 20 Old 05-25-2013, 12:10 AM - Thread Starter
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Thanks for the detailed response. I have an HVAC guy looking into options but he hasn't gotten back to me (busy time in AZ). I actually have about 18" of joist space that runs over the garage to an outside wall. I am wondering if it makes sense to run a couple ducts through there. My equipment is in an open space outside of the room, but I also wonder if it would make sense to pull warm air off the projector.

It is a small room, that I expect to have anywhere from 3 to 6 in there at any given time. We also do movie marathons, and I wouldn't want anyone passing out by during the second movie...

It would definitely be nice if I could pull it off with one piece of equipment.

Thanks again.
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post #8 of 20 Old 05-25-2013, 10:34 AM
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I am in the planning process for a theater room as part of a major remodel. The approach my HVAC engineer has come up with includes a Mitsubishi Mr. Slim ducted mini-split dedicated to the theater. The ducted air handler (mounted in the attic outside the theater room soundproof envelope) has a fresh-air intake. In my case, there will also be a dehumdifier, since the ambient humidity where I live can be very high. To balance the room pressure, the exhaust fan from the equipment closet will vent to the outdoors.l
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post #9 of 20 Old 05-25-2013, 12:29 PM - Thread Starter
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Thanks LeBon. That sounds like the type of set up I am looking for.
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post #10 of 20 Old 05-25-2013, 01:48 PM
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I might add that my minisplit is mounted in the rear soffit and if I had to do it all over again, I would have placed it in my AV room directly behind the theater and vented it into the theater. Even if I had to install a push fan. During quiet scenes, the fan of the mini is a little too much noise. Sure makes me appreciate the dead silence when it kicks off. It's not a deal breaker for sure, but a do over would have me moving it.
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post #11 of 20 Old 05-25-2013, 02:11 PM
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LeBon, can you share the model?
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post #12 of 20 Old 05-25-2013, 06:03 PM
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Quote:
Originally Posted by LeBon View Post

I am in the planning process for a theater room as part of a major remodel. The approach my HVAC engineer has come up with includes a Mitsubishi Mr. Slim ducted mini-split dedicated to the theater. The ducted air handler (mounted in the attic outside the theater room soundproof envelope) has a fresh-air intake. In my case, there will also be a dehumdifier, since the ambient humidity where I live can be very high. To balance the room pressure, the exhaust fan from the equipment closet will vent to the outdoors.l

That sounds like a good setup. I think it's worth making "fresh air" = outside air. Not sure what you have planned, but I've seen a few builds where fresh air is just air from another room. I have conventional forced air and an ERV. The forced air is quiet and I love the air quality improvement the ERV brings with fresh outside HEPA filtered air, but it's loud. I think if I could have done the fresh air mixing in the AHU instead of the room, that would have kept the noise down. Are you using the model Roger recommended?

 

 

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post #13 of 20 Old 05-25-2013, 09:10 PM
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We have spec'd a Mitsubishi Mr. Slim SU2-KA12NA heat pump, and a SEZ-KD12NA4 ducted air handler (mounted in the attic outside the theater).

The dehumidifier is an Ultra Aire XT105H.

We will have an outside air intake, and an outside air exhaust (from the equipment closet).

The room will be about 19 x 21 x 9.6
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post #14 of 20 Old 05-26-2013, 08:21 AM
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Thanks LeBon - what's the reason for the dehumidifier?
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post #15 of 20 Old 05-26-2013, 10:00 AM
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Cool, but humid climate. We think 75 degrees is a hot day here, and it never gets below 32, but the relative humidity is routinely in the high 80's. We think that if we bring in outside air, we will need to control the humidity. Since the AC will not run much, we (Dennis Erskine) think it will take a dehumidifier to keep the RH down around 50%.

Do you think that's overkill?
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post #16 of 20 Old 05-26-2013, 11:37 AM
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Thanks, makes sense - I'm not familar with the Pebble Beach climate, I'm in So Cal, and humidity is usually fairly low.
Quote:
Originally Posted by LeBon View Post

Do you think that's overkill?

Probably not if Dennis suggested it - maybe good insurance against mold (speculating)
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post #17 of 20 Old 05-26-2013, 07:16 PM
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I want to get dehumidification as well. Dennis spec'd my ERV's. I like them, but they make humidity worse. There is some dehumidification that happens on the incoming air as part of the exchange, but the ERV isn't 100% efficient so there is still a noticable net gain in humidity brought in. I have to run the AC and ERV at the same time to deal with the humidity. The problem in the basement is its naturally cold down there, so the AC almost never kicks on. The ERV runs on a cycle - it can't be tied in with the main HVAC (the 2 don't talk). So it's bringing in fresh, but warm & humid air into a naturally cold space where the AC hardly ever runs. I think there is potential for a condensation problem. So I've stopped using it unless I'm down there generating a heat load and can run the AC without freezing. I think a dehumidifier after the ERV would be beneficial, but not sure how well they will work together in series.

I had originally thought about doing an external mixing room. Put a minisplit in there, ventilation, filtering, deodor, dehumidification, etc. Then duct that in through a powered dead vent. I'm kind of wishing I had gone that route, although hard to say what problems that might have created.

 

 

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post #18 of 20 Old 05-28-2013, 02:47 PM - Thread Starter
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Just stumbled on this spot ERV... http://www.amazon.com/Panasonic-FV-04VE1-WhisperComfortTM-Ventilation-Patent-Pending/dp/B000XJNZ1Y

Would somthing like this cover air intake and exhaust (maybe mounted somewhere near / over my projector), and be a complete solution with a ductless mini split?

It says it is 120v, and I was thinking I could wire it with my lights (just turn it on when using the room). My projector will mount a few feet from the front eves of the house, so maybe I could run the small ducts there?
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post #19 of 20 Old 05-29-2013, 10:19 AM - Thread Starter
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Anyone using a single room ERV like this (or have thoughts on whether or not it would work with a mini split)?

quick video: http://www.youtube.com/watch?v=-3CRGhu8C5I

Thanks.
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post #20 of 20 Old 06-18-2013, 06:43 PM
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Hello Pat, I am also in AZ and considering converting an existing 3rd car garage into a dedicated theater. Everything I have read has pointed me at a separate mini split similar to what LeBon posted.

I am still on the fence regarding converting the 3rd car garage as I am concerned about resale value. If I move forward I will be moving pretty slow. All that to say, I will be following all of your postings very closely!! smile.gif
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