HVAC Closets vs. Attic

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Hey gang, I'll try to make it brief.
I'm building a new 2 1/2 story house. I would like to put the HVAC equipment in closets on the 1st and 2nd floors, but our designer is pushing us to just stick 'em in the attic.
My rationale is that the attic installations tend to take up a lot of floorspace that I'd rather use for storage or something useful on the 3rd floor. Also, there might be some gain in efficiency with shorter duct runs and having the equipment operating inside the conditioned space.
So, what do you all think? Would you rather install/maintain equipment in a dedicated closet, or a hot attic? How big a closet would you like to see for this? I'd like to make it as easy as possible to work on. Any other words of wisdom? :-)
Thanks for sharing your opinions.
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Tell the designers that they can put them in the closets or they can look for another job. If they persist with their ignorance, drag them up into a hot attic and make them knee crawl, through all the fiberglass insulation, to the other side of the house where the air handler got put, then ask them if they are going to do a complete service on the unit?? and are they going to be willing to crawl up in the attic when its 100 degrees outside, on the 4th of July to replace a transformer, because the homeowner cut and shorted out the condenser control wire with a weed wacker.

think accessability for service, maintenance, and repairs.

Put the air handlers in closets, make them big enough so that you have a *MINIMUM* of 6 inches clearance on both sides, 1 inch on the back and 8-12 inches on the front behind the door if its all electric, and 12 - 16 inches on the front if its a gas furnace. Do check your local codes and the manufacturers instructions for the exact *MINIMUM* requirements. Ita always a real good idea to leave a little extra room, and make the access door frame a couple of inches wider than the unit to allow for replacement down the road.

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Thank you for your comments. They are quite helpful, and I agree 100%. I haven't spec'd equipment yet, so don't know the exact sizes, but was looking at doing a 4x5 foot closet, which should provide at least as much clearance as above.
There are three issues brought up by our designer for why he prefers the attic:
1. Lost floorspace in the living area - I can live with that. 2. Noise - I think I can live with that. 3. Zone dampers. Where to put them.? In a closet installation, all the ductwork will be concealed in soffits and ceilings, so where do you put the zone dampers where they will be accessible. I don't quite know how to address this one.
In addition, since all the ductwork will be inaccessible, I'm pushing for all metal ductwork instead of flex. I think this may also be causing our designer some heartburn, as he has to be a bit more careful to leave space to route it.
Thanks much!
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OK... that works... however 4x5ft is a bit of overkill

He's getting paid by the sqft.....it cuts into his bottom line

If the system is correctly designed and sized, it should be almost virtualy silent

Each system will be its own zone... unless you have less than about 800 sqft, or more than about 2500 sqft or so per floor, zone dampers shouldn't be an issue.

Get the correctly designed and sized tin ductwork....when done right, it will last the life of the house and is a 1 time expense, where flex *WILL* have to be replaced repeatedly over the life of the house.

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That's good to know. I won't push to make them any bigger than that, which should make our designer happy.

Our floors will be, I think, in the 2000-2500 sqft range. So, you're saying that, at that size, there's not much benefit in zoning within a given floor? I can see that, I suppose. I was thinking that some zoning might be nice for convenience/comfort, though. So, for example, the kitchen could get extra air when it's hot in there, without freezing the rest of the floor. (A problem we have now.) Is that worth doing, and if so, back to the original question...where to put the dampers?

I'm going to push for that. Finding a company willing to do it that way may be a challenge around here (Houston), these days, sad to say.
Thanks!
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wrote:

Dampers usually go on the main trunk lines. FWIW, with a correctly installed system with properly sized and designed equipment and ductwork, there should be no more than a degree or so temp diference between any 2 rooms....including the kitchen. Keep in mind that the kitchen needs to have proper supply and exhaust ventilation, as well as utility room(s). Think about having an ERV or 2 installed.

They are out there, its just a matter of finding one... and no, they will not be the lowest bidder.

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So, if I understand you correctly, you're saying that zoning is probably more trouble than it's worth, in this case. Well, I can live with that, I suppose. About the only thing we'd really give up is individual control of some (or all) bedrooms, which would be nice, but not absolutely required.

No argument there. I expect that it's not going to be cheap to do it the way I want to. But, hopefully, if I do it the right way, I'll only cry once, as the saying goes.
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wrote:

installed
should
have
Yeah, but when was the last time you cried over the cost of something? Do you remember?
Now, when was the last time you bitched over something that was designed wrong? Today, yesterday... I bet it wasn't long ago. :-)
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snipped-for-privacy@hatespam.com (Longtime Lurker) wrote:

have you did any research whatsoever on zoning? One very important facet to remember is for the most part, residential hvac systems are constant volume Oh sure, they may have a variable speed blower, but they're moving a fixed cfm thru the coils. Now along comes a zoning damper that closes and what happens to the air that was going thru the coil and down that duct? Where does the extra air go? Well, some systems would then have a bypass damper, such that the air you just paid to be cooled is now dumped right back into the return air. Now you pay to cool it again. Pretty soon the supply air temp sensor says Hey, I'm too cold & therefore it will cycle the compressor off so the coil doesnt freeze.
Cheaper zoning systems have dampers that are either open or closed, far better systems have dampers that modulate from 0%-100%. Another critical factor is upsizing the branch ducts to accomodate the extra airflows imposed when zone dampers modulate closed. Then there's the bypass system. Cheap, barometic control or modulating motorized control. Does your zoning system have communicating thermostats & is it web-enabled?

Regarding the tin ductwork: I'm in Ca and easily 95% of ALL homes in Ca have flex duct installed in them, even brand new homes. I'll venture a guess that you will not find a resi hvac contractor in Houston that installs metal ducts in attics or in new resi, unless its a custom home. Sealing sheet metal when its crammed into tight soffit areas etc just isnt going to happen. I'd rather have a tight flex duct system than a leaky tin system anyday.
Another form of sheet metal is the insulated aluma-flex duct. This stuff is great, as long as you dont have to trim to fit or dont squash it. It's very easily damaged, and no way to re-straighten it. Personally I think you're far better off with R8, mylar jacketed flex duct. Pricier than R4.2, but for mor energy efficient as well.

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2 Stage AC!!!!!

I hate Flex, and will not use more than 6' at any one time, properly installed it will not need to be replaced, but we are one of those crazy resi company's that use all metal except for returns and connectors

Are they still selling 4.2, I thought it all went to 6 and 8!

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None of the vendors in my area are stocking R8, even though it's code statewide. Most bldg dept's dont enforce it. I witnessed a remodel of a City bldg where I pointed out the specific codes to the building officials, and yet the R4.2 FSK remained.
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snipped-for-privacy@gonefishin.net wrote:

So, is this another vote for zoning being more trouble than it's worth? That seems to be what everyone is saying, here.

Well, it hasn't been spec'd yet, but that would be nice!

This is, in fact, for a custom home, designed from scratch, which is why I'm soliciting advice here on what to tell the designer to include to make the HVAC work as well as possible. I'll look into the flex you mentioned, but I'm still leaning towards metal, if at all possible, and trying to get the designer to leave adequate room to install it.
I'm sure you're right, though, it's going to be hard to find a residential contractor to install metal. I've looked at a lot of new homes lately (to get design ideas), and I always peek into the attic. I've never seen anything other than miles of flex running every which a way.
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On custom homes we almost always zone the master suite from th erest of the second floor, and the main living area (kitchen, family room, and entry from th erest of the first) Seperate trunkline for each zone!
--
Bob Pietrangelo
snipped-for-privacy@comcast.net (home)
  Click to see the full signature.
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That would be nice! I'd love it if, at least, the master could have it's own thermostat. Ideally, it'd be nice to give each kid one, also, but that might get a little pricey.
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I tried to send this direct... it bounced. I'm not re-writing so let the flame begin.
I posted at the long end of the replies... after reading the lot If you want real zoning real comfort & few or no air handlers at all... Go to mehvac.com Mitsubishi Electric of America. Look at the PUMY series of HVAC equipment. The PUMY is an air source heat pump that can have up to 8 indoor units on a single 4 ton outdoor. The inverter drive operates from 30% to 130% (5tons) of capacity & is dirt cheap to operate in comparison to anything else on the market. The larger units PURY & PUHY's can handle up to 24 indoor units on a single outdoor. The PURY is a simultaneous heat & cool unit that's very efficient for commercial purposes. Neither the PURY of the PUHY are realistic for residential installs, but a couple PUMY units will suit your purposes perfectly. I have been working with these for a number of years & have had great performance results.
I hesitate to post this response in the newsgroup, as there are a number of folk that would scream of blasphemy. Most are air heads (force hot & cold air) & a few are wetheads (hot water chilled water or DX) A few might have heard of "mini-split" systems, but these are multiple minisplits for lack of a better word & I doubt many have used them. You might try posting a question in that regard.. I'd also "ping" Abbey Normal in the group. He's probably heard of / installed these as he's a tech in the islands... these systems are going in al over FLA. & points south. I've seen his posts around, but I haven't lurked this group for a while, haven't posted for years. Too many control freaks as far as I'm concerned. That said, find a good refrigeration contractor that's installed this system before & I'll guarantee you'll love it. Houston(?) is a perfect application as your heating design temps never reach the subzero's as they do here in MN. & the units can provide heating easily down to 15dF, a region I doubt Houston will rarely see.
This system will also win the praises of your designer as you'll need NO mechanical space, or any you do use, for ducted units, will easily fit in the soffit spaces you've already agreed upon. Depending on the layout of the home, you could have a separate zone for every room. I'll recommend an ERV for ventilation as well, but that's an easy fix. If your interested, I can contact Mitsubishi in Atlanta & ask them for a list of the best contractors in your area. I won't make a penny on it, but I hate to see a bad system put into a decent house. I can also guarantee you'll save some serious cash on cost of operation & it will pay for itself in less than 10 years, maybe less.. If I had a set of plans I could run a room by room load & cost analyze the whole thing. I can lay it out on cad if you like. That's what I do, as I stated in my post (the end of the longest thread) I've been doing it for years & I do it well... The only other thing I do well is snow ski, & I've done that since I was 2.
good luck geothermaljones st.paul,mn.
wrote:

the
from
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Abby is still around... he pops in from time to time.
wrote:

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Well, I've heard of them, but have never seen one in any of the houses we've toured. So, I'm pretty ignorant. Forced air is far and away the only thing you see down here. In Houston, AC dominates of course, and heating is usually an afterthought at best. Dehumidification is also a key consideration, and especially so for me, as I'll be 3/8 mile from a major river.

I'll definitely check it out.

15?! Yeah, we might see that once or twice...a decade. :-)

Yeah, I'm sure he'd like that!

Definitely looking at an ERV, anyway. And, from what I've read, in a high humidity climate, it might make more sense to run completely separate ductwork for it. If so, then the ERV could work with anything.

Well, hold that thought! I'm still at the beginning design stage, so it'll be a few weeks until the layout is finalized. But, I'm trying to push the HVAC design considerations now so I can get these things addressed before it's too late. Also pushing for extra insulation, radiant barriers, low e windows, shading, attention to solar angles, etc. in hopes of taking as much heat load off the building as I can.
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8-12
inches
Your serviceman will like you for it too. :-)

You sure can... cause if it's done right, it won't matter where it's at... as you won't hear it anyway.

They can be in the closet. Or you can still run the ducting in the attic and put them up there. Dampers don't require a lot of maintenance, so it's not that big of an issue.

I would REQUEST metal... PERIOD!

That's tuff shit... that's why he is a designer... it's his job.

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Well, I'd rather not run the ducting all the way up to the attic, and back down. In the closet would be good, if there's a convenient place to branch off there. Otherwise, I guess I'm looking at access panels in closets or something like that. Is that doable?
I hope they don't need much maintenance, but since they're electrical AND mechanical ... well, sooner or later!
Thanks!
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wrote in message

and
not
Was talking about the upstairs unit.

Yep, only your imagination limits the possibilities. :-)

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