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post #1 of 23 Old 07-11-2016, 06:01 AM - Thread Starter
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Does minisplit location matter?

I'm meeting with a few HVAC companies to figure out the best way to do HVAC in my theater, and am running into some conflicting information. One guy said I didn't need to worry about fresh air because of the mini split (and if I wanted some, just open the door -- he's been removed from consideration). One guy suggested an ERV to circulate fresh air in the basement, and another guy talked about ducting to the main HVAC but making the vents oversized (to reduce noise) and using flex ducts.

Before I talk about the mini split, I want to highlight that I live in Minneapolis, where we get 100F days in summer and -20F days in winter (not often, but it happens).

With regards to the mini split (my main question here), one of the contractors said I'd be fine putting it against the back wall (option 2 in the picture). The other guy said that I wouldn't want to do that but should instead put it on the side wall (option 1). I don't really like option 1 because that's where the surround speakers will go, but if I put it in the back of the room, am I going to have problems because the room is roughly 35' long? I assumed if I had a return vent near the screen somewhere that it would pull the air from the minisplit towards it, but maybe I'm wrong there.

Any feedback would be greatly appreciated as I try to figure this all out. Thanks!
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post #2 of 23 Old 07-11-2016, 07:05 AM
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Quote:
Originally Posted by Fezmid View Post
I'm meeting with a few HVAC companies to figure out the best way to do HVAC in my theater, and am running into some conflicting information. One guy said I didn't need to worry about fresh air because of the mini split (and if I wanted some, just open the door -- he's been removed from consideration).
For what its worth, I am investigating the same questions. Ted White indicated to me that introducing a fresh-air return adds complexity and maybe complications on the sound side of things, and that in many rooms it was not needed unless you intend to keep the door sealed for long periods of time. So that is something you have to weigh.

That said, one thing I am looking into is a Fujitsu mini split, because it appears that you can add a fresh-air return kit to it. Maybe this will kill two birds so to speak. But I have not gotten any feedback yet on its effectiveness.

Good luck.
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post #3 of 23 Old 07-11-2016, 09:46 AM
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My room is only ~ 22 1/2' x 17 1/2', but my mini-split is on the Rear wall, very close to a side wall.

In my set-up, it works fine as it is and I don't feel any particular 'hot or cold' spots... so, fairly happy with the rear wall. I could have done one on the side, but aesthetically, I didn't really want to. I would think if you had a return up front, that could help with the circulation.

I also set up a fresh air supply in to the room (pulling air into the room, from our large open floor plan remainder of the basement), and a fan to 'exhaust' from the theater room.

I have had up to 16 people (many of which were kids) squished into my theater, and never used the set up for air exchanges... albeit, for a single movie. I would add though, the current set up I have to pull air into the theater, is a bit loud... so, that could play into it, but it hasn't been a need for me to change out the fan I have to pull the air in.

Also, in my personal experience, the more people in the room... the more the doors open & close for bathroom, drinks, etc, so, that could help with the fresh air.
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post #4 of 23 Old 07-11-2016, 01:32 PM - Thread Starter
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Well here's something I hadn't heard anybody else say before regarding using the mini split in winter. Apparently extended AC use during winter will make the machine fail in less than 5 years? Anyone in a cold region (ie: Minnesota) have that experience? He also doesn't think I'll need to use it much in winter anyway, so... :/

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There is a caveat I mentioned to both you and Doug regarding cooling in the basement during outdoor temperatures under 32 F. I spoke to the factory rep for Mitsubishi this morning and he was quite clear that running the a/c for lengthy periods in those temperatures will burn out the compressor system well before the 12 year warranty and it will not be covered under warranty because the systems were not built to provide cooling in rugged temperatures. I have a client who has a photography studio in Eagan in the basement of his house. His system runs nominally during the winter to maintain 60F in his darkroom. You should plan on only using the cooling in the winter if the temperature needs to be around 68 to 70F in your room. Any higher demand which will cause extended runs in low outdoor temperatures will decrease the life of the system.
The manual for the device says it cools all the way to 14F outside (and heats down to -13F), so... Not sure why it would burn out and why it wouldn't be under warranty.
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post #5 of 23 Old 07-11-2016, 01:41 PM
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I haven't heard it, but there is lots I haven't heard and that doesn't mean it isn't true!!...

I live in southern Ohio, a north suburb of Cincinnati, and my theater is in the basement... of the times I have used my Mini-Split, probably 80%+ have been the heater, I haven't used the AC much at all. I tried with our first large party, but my unit didn't have enough Freon :-(

Obviously, if your theater will be above grade, I would think the AC is much more likely to be used...
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post #6 of 23 Old 07-11-2016, 01:55 PM - Thread Starter
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Quote:
Originally Posted by kmhvball View Post
I haven't heard it, but there is lots I haven't heard and that doesn't mean it isn't true!!...

I live in southern Ohio, a north suburb of Cincinnati, and my theater is in the basement... of the times I have used my Mini-Split, probably 80%+ have been the heater, I haven't used the AC much at all. I tried with our first large party, but my unit didn't have enough Freon :-(

Obviously, if your theater will be above grade, I would think the AC is much more likely to be used...
That's good to hear. Mine's in the basement as well, and the HVAC guy was saying he doesn't think I'll need to cool in the winter; sounds like that matches what you're experiencing which is good.
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post #7 of 23 Old 07-11-2016, 02:06 PM
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If you go with a Mini-split... consider your wall/ceiling colors, and decide if you are interested in painting it... if so, it would probably be easier before you put it up... or at least before painting/finishing around it.

I didn't paint mine, and when I posted my theater in the "Show me your finished theater" thread, someone recommended it... so, I decided to do it, and am happy I did, but it was a bit of a pain... I already had my fabric panels up (which i could remove), room carpeted, etc.. With my decor, the white really stuck out... obviously, if you have lighter colored walls, etc., not a big deal (and not a huge deal even with dark walls!!).
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post #8 of 23 Old 07-11-2016, 06:22 PM
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Quote:
Originally Posted by kmhvball View Post

I also set up a fresh air supply in to the room (pulling air into the room, from our large open floor plan remainder of the basement), and a fan to 'exhaust' from the theater room.

I have had up to 16 people (many of which were kids) squished into my theater, and never used the set up for air exchanges... albeit, for a single movie. I would add though, the current set up I have to pull air into the theater, is a bit loud... so, that could play into it, but it hasn't been a need for me to change out the fan I have to pull the air in.

Also, in my personal experience, the more people in the room... the more the doors open & close for bathroom, drinks, etc, so, that could help with the fresh air.
Just to be clear, would you skip this step and not build a fresh air return system if you had to do it again? (Your room looks awesome by the way.)
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post #9 of 23 Old 07-11-2016, 10:41 PM
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First question is, do you intend to isolate your room?
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post #10 of 23 Old 07-12-2016, 03:49 AM
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Quote:
Originally Posted by jjackkrash View Post
Just to be clear, would you skip this step and not build a fresh air return system if you had to do it again? (Your room looks awesome by the way.)
I probably don't think I would add an air exchange process again, since I never use it and it provides two more, fairly sizeable holes in my sound-proofing shell. The cost & effort to make the right muffler/sound containment in order to provide something I don't use, isn't worth it.

My 'usage pattern', also plays into it... rarely am I ever in my theater for more than 1 movie or the length of a super bowl. Net, I am not in the theater hours on end, needing the fresh air. If I felt I was going to leave both my doors closed (communicating doors at the entry), and stay in the Theater for longer durations, then I would...

Having said all of that, I am probably an outlier when it comes to this point of view. It makes me feel slightly better knowing Ted White may have mentioned a similar notion, that it isn't 100% of the time needed.

My guess is someone who designs theaters for a living like @SierraMikeBravo , would probably never design a theater with out fresh air exchange process... so, take my 1x home theater build as what it is, one individual, with one Home Theater room ever worth of experience
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post #11 of 23 Old 07-12-2016, 06:45 AM
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Kevin, thanks for the input. Its the extra holes I'd like to avoid. I want to do things "right," but my usage at least right now closely matches yours and I'm not sure adding extra holes is worth it. On the other hand, I don't want to get the build up and figure out I need fresh air after all the rock and trim are installed. Hmm.
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post #12 of 23 Old 07-12-2016, 06:57 AM - Thread Starter
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Quote:
Originally Posted by jjackkrash View Post
Kevin, thanks for the input. Its the extra holes I'd like to avoid. I want to do things "right," but my usage at least right now closely matches yours and I'm not sure adding extra holes is worth it. On the other hand, I don't want to get the build up and figure out I need fresh air after all the rock and trim are installed. Hmm.
I'm in the EXACT same boat, not sure what the "right" answer is....

The contractor came back and said he doesn't recommend the minisplit and instead recommends regular ducts (although he'll do either, or both). The ducts are a lot cheaper, which is nice, but I think I want the extra flexibility of the minisplit. Having the engineer come over to look it over.
@SierraMikeBravo , the room is isolated -- using DD/GG, clips/channels on the support wall and IB-3 on the new framing in the room.
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post #13 of 23 Old 07-12-2016, 07:36 AM
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Then I would highly recommend you not use a in room mini split system. Use a conventional system or a ducted mini split. Introducing noise into your isolated room has just negated isolation in the first place.
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post #14 of 23 Old 07-12-2016, 07:41 AM
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Further, you don't need an engineer in my opinion. What you need is someone who has done this many times over. Right now, all the professionals you're bringing over have never done this before. Hire a designer with HVAC experience.
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post #15 of 23 Old 07-12-2016, 08:14 AM - Thread Starter
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Quote:
Originally Posted by SierraMikeBravo View Post
Then I would highly recommend you not use a in room mini split system. Use a conventional system or a ducted mini split. Introducing noise into your isolated room has just negated isolation in the first place.
I've seen many people here say they've used the ductless minisplit though - specifically the Mitsubishi because the noise level is only 22db, which is far lower than the noise floor of the room. Is that not accurate?
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post #16 of 23 Old 07-12-2016, 08:31 AM
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I use a Mitsubushi Mr. Slim, and I can frankly barely hear it with out a movie playing... and certainly don't hear it with a movie playing. I have seen many others with the same unit who share my experience...

I did do clips & channel on ceiling, dual separated walls all around my room, IB-3 clips to attach walls to rafters... I used all 5/8" full weight fire rated DW, and did GG/DW/GG/DW on my sub-floor, and then DW/GG/DW on my ceiling & walls, and my entry door wall are double walls, with an exterior door (i.e., sealed all around) on the 'outer wall', and I used the Zero International seals on my interior 1 3/4" solid wood door.

My room is very quite if I am sitting in it with nothing playing and not shuffling around at all... I can 'hear' the Mr. Slim at that point, but it isn't very loud... once you get people talking, or turn on the movie/music, then the minor mini-split sound is definitely drowned out.

I would guess a properly designed, ducted HVAC with the optimal air-flow rate, would likely be better & provide a lower noise floor... but for me, the cost of the Mini-split, was less than trying to use my main house HVAC system (which, doesn't have Zone capability already), with the proper air-flow/CFM, while maintaining the minimal transmission of sound through that system.

My impression was that most zoned systems, need to be 'consistent' either Heater or Air Conditioner... and my Mini-Split isn't always 'tuned' the same as the rest of the house... for instance, I'll put on a low heat even in the summer in my theater, and the rest of the house is on A/C... not sure if some systems enable the balance of house to be on A/C and one particular room on Heat or not. Similarly, one of the few times I have used the A/C on my unit was in the winter with a bunch of people, and the rest of the house was using the 'heater' at the same time.
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post #17 of 23 Old 07-12-2016, 09:57 AM
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Using an in room mini split cuts through the isolation shell. Since the unit interior is not isolated, it introduces the possibility of mitigating your isolation you spent a lot of money on. Second, it is ideal to place the forced air toward the front of the room. This allows for air to better circulate in the room as your CAR should be in the rear of the room to allow venting of the projector and the BTU's put off by body heat. It is wise to invest in the ducted mini splits or a dedicated conventional system.
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post #18 of 23 Old 07-12-2016, 09:58 AM
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There are several reasons, but those are two for brevity purposes.
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post #19 of 23 Old 07-12-2016, 10:45 AM
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I certainly can't argue at all about the best location of the unit & air return, everything mentioned makes sense to me. The experts/ professionals such as SierraMikeBravo have studied and tested way more about this than I could ever imagine.

Given I did do a min-split with the in-room unit/air handler, I am happy with the location of my unit and wouldn't change it despite, the apparently sub-optimal functional location. This is entirely based on the aesthetics of the in-room air handler and how trying to fit it closer to the front of my room would look. One of the benefits of the ducted mini-splits or conventional forced air systems, is you don't have the same aesthetic concern as with my kind of Mini-Split. If I were to do it again, I would learn more about the ducted Min-split option.

In terms of the 'sound proofing' compromise, I don't find it to be a big deal. The entire penetration in my room shell for the on wall unit, is a circle, I would guess is 2" in diameter (insulated copper tube & electric wire). In that immediate area, I added an extra layer of DW between the studs & placed extra insulation around it, and it doesn't seem to leak sound much.

In general, I strived for 'quite good', not 'perfect' in my theater. I unequivocally know that if I had Erksine Group designed my theater/ acoustic treatments/ av system, it would have delivered a better total performance...but, I am not an audiophile or video-phile, so, for my personal needs... what I have is fantastic in my opinion (and in the opinions of others who have visited the room, all of whom are also not true audio/video experts). I had a higher end realtor in my home recently, who said she has sold ~50-100 homes with dedicated home theaters... and she said "wow, this is really nice, is this what you do for a living?"... so, I took that as a compliment :-) Having said that, the entirety of my Home Theater knowledge is from reading largely on this site, so, quite limited vs any professional. I am just sharing a perspective of someone who strived for quite good, not perfection... not everyone is willing to spend the extra money to go from quite good to perfection.. I like to think I got 80+% of the benefit for 20-30% of the effort/cost. Naivety and ignorance of how good, good can really be, is nice sometimes :-)
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post #20 of 23 Old 07-12-2016, 03:15 PM
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Quote:
Originally Posted by SierraMikeBravo View Post
Using an in room mini split cuts through the isolation shell. Since the unit interior is not isolated, it introduces the possibility of mitigating your isolation you spent a lot of money on.
I am not sure I am following and I'm trying to wrap my head around this. The mini split has a small pipe leading to the outside where the condenser lives, and that's basically it. It seems like I could anchor a port in my double wall and caulk it and the port would still be decoupled. If you add air-return ducts and vents you are adding big holes to somewhere else in the house, even if they have mufflers or are dead vents. Why are holes for vents different or better than a small, 2" hole for mini split? Is it just having the unit in the room that is bad?
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post #21 of 23 Old 07-12-2016, 03:18 PM
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Also, is there any reason other than maybe cost to heat or cool that would make it a bad idea to run a fresh-air return to the outside rather than in the rest of the house if I wanted to add a fresh-air return? Wouldn't this be better than vents and ducts running inside to the rest of the house for isolation purposes?
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post #22 of 23 Old 07-12-2016, 03:39 PM
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It depends on the type of unit you go with, but ANY penetration into the shell, if not dealt with properly, can mitigate the shell. To answer your question, yes, it's not the best for aesthetics or acoustics to have the unit inside the room. It is best left outside the room. I have designed rooms with the unit inside, and it isn't ideal. It gets back to the idea as well that for best circulation the forced air should be toward the front. Any penetration into the shell is a weak point, so best to keep them minimized. Even the smallest crack can lead to problems with the isolation. Spend the extra money and go with a dedicated or ducted mini split.

As for your other question, sit down and honestly take a hard look at what you are doing. Saving a few dollars, you are trying to accommodate the mini split and compromising the performance of your system rather than designing the room to the best it can be within your budget. Again, any penetration is a weak point. By ducting the system, you solve your problems rather than creating new ones.

Last edited by SierraMikeBravo; 07-12-2016 at 03:44 PM.
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post #23 of 23 Old 07-12-2016, 04:08 PM
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Quote:
Originally Posted by SierraMikeBravo View Post
It depends on the type of unit you go with, but ANY penetration into the shell, if not dealt with properly, can mitigate the shell. To answer your question, yes, it's not the best for aesthetics or acoustics to have the unit inside the room. It is best left outside the room. I have designed rooms with the unit inside, and it isn't ideal. It gets back to the idea as well that for best circulation the forced air should be toward the front. Any penetration into the shell is a weak point, so best to keep them minimized. Even the smallest crack can lead to problems with the isolation. Spend the extra money and go with a dedicated or ducted mini split.

As for your other question, sit down and honestly take a hard look at what you are doing. Saving a few dollars, you are trying to accommodate the mini split and compromising the performance of your system rather than designing the room to the best it can be within your budget. Again, any penetration is a weak point. By ducting the system, you solve your problems rather than creating new ones.
Ok, I truly appreciate your input, and I agree I want the best performance. My actual tendency is to overdo everything, so I am really just trying to understand the best way. I have an HVAC guy coming this week to see if he can help me and I want to be able to talk to him with some knowledge in this subject, as I strongly suspect he won't have the "dedicated room" experience as you indicated above.

Currently, we live in the PacNW on the Puget Sound and don't have central air. We need AC in our 3d story bedroom maybe 3-7 times a year, the basement is cool all year round. So whatever I do for the sealed room, its going to be separate from the rest of the house unless its just a dead vent to another room because the rest of the house doesn't have AC.
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