FINISHED IN 2020! Sharward's Partial Garage Conversion

[sharward]

I just spoke with a kind and helpful customer service representative at Soleus International, Inc. We talked about my situation (she even looked at the last couple of pages of this thread to see my illustrations). Here's what I learned:

• They're serious when they say you can't extend the hoses.
  
  They're serious when they say you have to keep the lines as straight as possible. "Arcing" the lines is OK but "bending," especially at 90 degrees, is very bad for the system. She said the air bounces off the wall of the 90 degree turn and comes back towards the unit (in the case of exhaust).
  
  Extending the lines and using booster fans at the end to push air in (intake) and pull air out (exhaust) may work, but they can't guarantee it (obviously). She knows of a case where someone used a booster fan on a unit with an exhaust line and it seemed to work fine. However, she recalls that unit was not the same as the MAC-10K which has two hoses (one intake, one exhaust).
  
  There is an intake vent behind the unit, near where the hoses connect, which means enclosing the unit in a niche without a generous clearance around it will not work.

She suggested I place the unit along the long wall closest to the outside to accommodate an "as short as possible" run. I'm concerned about what that would do to my isolation though.

The rep was very helpful in trying to advise me to do such things as making sure I know what the return policies are of whatever retailer I purchase from, so that I could return it if it doesn't work out. I had to explain that if it doesn't work out, my entire project doesn't work out, so the prospect of a restocking fee is the least of my concerns.

This is not fun.

I just sent e-mail to a former coworker of mine, who is a musician and works for an HVAC company. Maybe he has some ideas.

[sharward]

Man, it would be so great if I could find one of those portable units that allows for longer duct lengths...

Ta-da!!! I just found the industrial-strength MovinCool Office Pro 10 that allows for a 25 foot duct length!! There also aren't the same dire warnings about keeping the hoses straight. I'm sure it's better to keep them straight, but I would think that the 25' length spec means the fans are more powerful and might be able to handle a few 90 degree bends...

It's quite a bit louder than the Soleus model... (58db vs. 46db), but its flow volume is higher (205 CFM vs. 176 CFM). It also has a much larger water tank capacity (2.4 gallons vs. .8 gallons) -- and they also offer an optional condensate pump that will allow the water to be drained "up hill" up to 18 feet, so there'd be no problem getting the water to flow in a pipe over the doorway.

All of this comes at a cost though -- the retail price is US$2,079 -- but I see I just missed this new one on eBay with a scratch on it that sold for $202.50 , so it may pay to watch eBay for a while!

The other thing that appeals to me about this is that I'll have something to keep me cool while I'm doing construction!

I think that this thing, along with some creative installation, will be my winning ticket!

[sharward]

Gravity sucks. Just when you're flyin' high and soarin' like a bird, enter Gravity to kill the buzz.

All along I've been assuming, incorrectly, that the dual hoses in these portable air conditioners are to cycle the room with fresh air.

Bzzzzzzzzzt! Wrong answer! The dual hoses are there to cycle the equipment with fresh air.

That means that while the air conditioner is breathing, the room is not.

Therefore, the portable air conditioner is really no better than the mini split in my situation.

However, not all is lost. I learned a bit about air circulation in the past couple of weeks. I also learned to simplify my thinking about my challenges:

• 1. I need something to keep the room comfortably cool.
  2. I need something to supply me with fresh air.

These are two separate an distinct challenges and they do not have to be accomplished with one system.

Like a ton of bricks, it hit me -- my ventilation requirement is to address my lack of window. My undertanding of building codes is that I can make up for the lack of window with a mechanical ventilation system, adequate lighting, emergency lighting, and a smoke detector, provided the room not be used for sleeping purposes. Two documents that illustrate this are Natural Light for Home Theater, City of Golden, Colorado, Building Division, Policies & Procedures and City of Boise, Idaho, "IRC Code Section R303: Light & Ventilation".

My city uses a different set of model codes, but I'm pretty sure they're similar. This is something I will need to verify.

So, since the MovinCool system is "getting up there in price" to get close to the cost of a mini split, why not go ahead and do the mini split, and then come up with a simple ventillation system to cycle air in and out of the room on demand?

My room will be around 1,300 cubic feet (that's a liberal estimate). If I aim for a full air exchange every half hour (the greater requirement of the two referenced above), that's 650 cubic feet every 30 minutes, or a little over 20 CFM, an easy level to reach. I'd actually want it to be much better than that.

The challenge will be allowing air to be exchanged with the outside world without allowing sound to leake out to the outside world.

For simplicity's sake, I'd prefer that the ducts penetrate to the outside in the area between my leaves, between the doors. However, there may not be enough space in this area to accomplish this successfully. If so, then the ducts could run the depth of the house and follow the same path that the mini split lines would to the southeast corner (about 30-40 feet).

The cool thing (no pun intended) about this solution is that, during colder months, I may not have to run A/C at all -- I can simply run the ventilation system to pump 50-60 degree (Fahrenheit) air into the room.

So much for the $500 air conditioner idea...

Dan, on the phone yesterday you said you had some ideas for a duct silencer. Perhaps you can share them now, as they may be helpful in coming up with a plan for my ventilation ducts.

[Dan Fitzpatrick]

Hi Keith,

I'll try to get some stuff up soon, I'm busy at work crunching away for the next few days (working sunday again )

on the CFM, make sure you start with a LOT of CFM like over 100 or maybe even more to be sure you end up with your 20 after the air has gone through all the twists and turns. every turn/distance takes away from the nominal CFM number ... a lot of advertised CFM numbers are for UN loaded fans, once you hook it up to your the fan loses efficiency.

some designs of fans work muhc better than others when working against static pressure. get a fan that tells you how much CFM you get with a given static pressure.

more later

[knightfly]

Does reviewing this help any?

http://www.johnlsayers.com/phpBB2/viewt ... &start=180

[sharward]

Thanks for the advice, Dan. I'll be sure not to get too excited when I see CFM ratings without doing the math. I'm looking forward to learning more about this from you.

Thanks for the link, Steve. Yes, I had seen that thread and those illustrations a number of times, but it's good to see it again.

Steve, your illustrations indicate four 90-degree bends. Is this a minimum? Is there a minimum total length to account for? Do these figures differ depending on the diameter of the ducts? Is square better than round? (I already know that "flex" ducting is bad.) Is it OK to have all the winds and turns" occur between the leaves, or will I get better performance if they're outside the outer leaf? Please tell me everything I need to know about ducting!

[sharward]

I popped into my friendly neighborhood permit center today for a bit of information. (And, yes, today they were actually very friendly!)

• CBC does in fact allow for mechanical ventilation as an alternative to a window in habitable space, provided it is certified as capable of doing a full air exchange every 30 minutes, or as much as 15 cubic feet per minute per person occupying "the building." I'm interpreting that as the number of people being in the room. Figuring 5 people in the room (oh how cramped that would be ), that's 75 CFM. I'm going to need some good fans and ducting! (But I'm not worried.)
  
  I confirmed in the almighty CBC book that it's OK to notch ceiling joists on their ends up to 1/4 of their total height. That means if I use 5 1/2" tall ceiling joists, I can notch out 1 1/8", reducing the height at the end(s) to 4 3/8", to get them to fit on top of the exterior wall top plate below the descending roof line. This is a relief, as I was a little worried about not being able to squeeze them in that space. I haven't measured it yet, but I'm confident it will work. (To see the cramped clearance I'm referring to, look at the far end of this photo).
  
  I also got a verbal assurance from the building inspector that, as long as I clearly document the intended use of the room (being for soundproof purposes), and I show that I'll install battery-powered emergency lighting, I should have no problem getting an exception to the "natural light" requirements (i.e., window or skylight) that all habitable space normally requires.

Can anyone point me to some good sources of information about ducting, exhaust fans, silencers, static pressure, that kind of thing?

Once I come up with a solid ventilation plan, and assuming I move forward with using a mini split for the A/C, all I'll have left is framing details to work up, and then I'm off to the city to get the alimighty permit! Needless to say, I'm really anxious to get going on this now!

[DreaminDrumBeats]

Glad to read the good news Kieth can't wait to see some building progress

[the dreamer]

http://www.acousticalsolutions.com/educ ... g_HVAC.pdf
(Icouldn't open that directly...save target..worked)
http://www.qwyatt.com/hvacapps.html
http://www.qwyatt.com/hvac.html (more interesting stuff there)
http://www.energydesignresources.com/do ... 3-hvac.pdf
http://www.chps.net/manual/documents/20 ... s/HVAC.pdf
http://www.naima.org/pages/benefits/ieq/noise.html

Hope that gets you started.
Florian

[sharward]

Thanks Florian!! Great stuff. I'll read these thoroughly when I get home tonight.

[sharward]

Thanks again, Florian! Great stuff!

And now, my cunning ventilation plan -- a.k.a., how I intend not to suffocate to death.

I had originally figured on trying to contain all of my ventilation ducting within the immediate area of my room. However, the more I learn about duct-borne noise, I'm seriously considering moving away from that idea -- in fact, doing just the opposite: running relatively long ducts:

• Fresh air pulled from my porch at front of house (shaded year-round), run along over 40 feet of ducting inside the garage, where it will stay cooler than if it were inside the attic. Air enters room near entrance of room, on wall above doors. Fan inside garage at end of line (far from room).
  
  Exhaust air pulled out if ceiling of room in opposite corner, run along about 40 feet of ducting inside attic over bedrooms and master bathroom to back of house. Fan located either (a) at end of line (quiet inside room, but may cause vibration on master bathroom wall -- not good) or (b) near laundry room (near location of attic access opening, for ease of maintenance).
  
  • Note: Building code may allow for my exhausting the air directly into the attic (much like a whole house fan) rather than venting directly to the outside -- this is something I would need to investigate.

Just doing a quick and dirty "in my head" calculation of static pressure using what I learned on Panasonic's "How to Size Ventilation Fans, I figure that each 40 foot duct run is actually the equivalent of 100 feet of straight-line duct when accounting for the bends.

Steve, do you think these relatively long duct runs with several 90-degree bends are sufficient for minimizing sound leakage? Do you think I will need to "upgrade" the ducts to one of the better performing lined ducts?

Dan, do you think I'm "getting it" in the area of static pressure and fan sizing?

All feedback always welcome!

[the dreamer]

Hi Keith,
if you look at the pics of my ventsystem I posted some time back, you notice the mufflers. It's more or less nothing else than an enlarged duct by 10cm full of rigid fibreglass hold in place by perforated sheetmetal. The effect is amazing: I had a guy talking at one end while I listened at the other. The loudness was really diminished although I heard the sound on my other ear that came normally.

What I mean is, if you build mufflers, plenum etc. I think you can get what you want. It just has to be carefully calculated.
In addition to these mufflers I have parts of the ductsystem lined with fibreglass and the inlets are a kind of "glassfibrelined" plenums to diminish the speed of airflow before entering the room. I hope this works out as predicted. I had a lot of talks with the guy who calculated this to make sure he understands what I need. You know that
Florian

[Dan Fitzpatrick]

Keith,

Probably after reading all those links Florian provided, you know more about this than I do. But I'm quite surprised to see such long duct lengths in your plan. The lenght seems unnecessary and means you'll have to have a bigger louder fan to make it work.

The other thing I'm not sure this design considers is how much sound comes through the wall of the duct, as opposed to the open end of the duct. The place where the duct leaves your studio, which is close to the neighbors (and the vent in your wall) is going to leak sound simply through the duct wall. it also doesn't seem like a good idea to route this duct along your critical neighbor side wall.

where the duct penetrates you have traded your massive leaves for thin sheet metal, it isn't going to perform as well obviously.

what paul woodlock did with his silencer system was to try and replace his two leaves, which he couldn't have because he needed the air, to replace them with what he hoped were equivalent massive silencers.

it is a two-silencer system which is analogous to the two-leaf system. in fact his silencers have walls that are the same thickness (7 layers) as his walls. one for his inner penetration and one for hte outer penetration.

here are a couple of diagrams i made to show what i'm thinking. this is MY interpretation of information i've gleaned from Paul's project and others. Just because there's a diagram doesn't mean it works caveat emptor and all that. but at least it will clarify what i'm talking about.

a couple of notes. from what i've inferred i think three things are critical with the silencer. 1) make it as long as possible. 2) make the rockwool as deep as possible. 3) make the surface area of the rockwool in contact with the air as much as possible. 4) did i say make it BIG???

according to eric desart having all the rockwool to one side of the air channel is preferable, to maximize depth of rockwool exposed to the sound. dreamer's go all the way around which is fine too, but not essential. again these are my interpretations of what has been said.

dan

[Dan Fitzpatrick]

i had a chance to sketch out the idea we talked about on the phone. this is sort of what i had initially planned to do.

now i'm going with just fresh air (no ac). so if you use a minisplit, our ventilation problems will be quite similar.

obviously you would need a similar system for the air out-take, which i didn't diagram. this would contain an exhaust fan (toward the outer end) that would help suck the bad air out and the a/c air in

also, i didn't diagram this but the idea is that all ductwork between the silencers and their respective leaves MUST have walls AS THICK as the leaves. otherwise sound will leak out (on the outside) or in (on the inside) through this weak point before it is absorbed by the silencer.

that is why i think it would be most convenient to build these silencers up against the leaves where possible to save material and effort.

dan

[knightfly]

I agree with pretty much all Dan said; especially about having same mass in ducts/silencers that you have in your respective wall leaves, for at least 15 feet or so; I read somewhere that duct noise attenuation increases per length up to about 15 feet, then levels off.

I don't think the long runs are optimum - if you have 10-15 feet, a bend, then 10-15 feet more, then another bend, that will (I think) be close to the point of diminishing returns. Longer than that will mainly increase static pressure thru increased duct friction.

If possible, use JM Superduct for at least the 15-20 feet of duct (inlet AND outlet) closest to the room, and don't forget the fact that your ductwork is a hole into the m-a-m envelope and needs to equal its performance.

Beyond the basic physics, I'm STILL a HVAC idiot; maybe you can get Rod to bless your plan, if so I'd build it in a heartbeat... Steve