Morning All,
I had meant to ask this question a couple of years ago and never got around to it. When I bought my home five years ago I wondered about why the AC/Furnace in both the attic (for the 2nd floor) and basement (for the 1st floor) were located along midpoint of the centerline (greater axis). I asked the superattendant that was around during the pre/post closing walkthroughs and he said it was a requirement by county code.
My home is about 55′ wide and about 25-35 deep depending on the location along the width. Both zones place the mechanicals dead-center along the home’s width. This presents problems in the attic (its 100% useless space even though the rathers peak at 18′.
I was wondering if anyone else has a county requirement like this, or if it was just easier for the HVAC installer with the superattendant just telling me an easy answer.
Replies
don't know code in your area but any time someone says "done to code" - ask to see the code site and point of reference - lot of people use "code" as an answer rather than giving specific answer to question - if the guy answering can't point to the "code" on the page in the book, mavbe it's "just the way they do things"
I only ask, becuase if its not a code requirement (maybe just makes an easier install) then that would be nice.
that's why I'd ask to see the code requirement - if you can move them, you get some place and maybe make for a "cleaner" installation
First, our code is state wide. I think most are. We use the national mechanical code though and it may be modified for NC. I don't know much about it, but would bet you that they located it like that not as a code requirement, but more just to make the system work better and for the convenience of the installer. Let's say he put it way over in one corner of the attic - so, now you have some duct runs that are 6' and some that are 45'. You see the problem. Plus it would be a pain to install service. There are likely dampers in each duct that can be used to compensate for duct length and other variables, like room size, but my experience is that HVAC guys rarely mess with the dampers. More often than not, "code" is going to be "per manufacturer's instructions". So, that is a good place to start. The paperwork for the units is often in a plastic envelope stuck to the side of the unit. Also, there are manufacturer's requirements re access to the unit, but it is normally just something like "30 inches clearance on the service side of the unit and 24" on other sides."
To get an answer to your question you will have to call your local building inspector's office and ask to talk to someone who does mechanical inspections.
BTW - I'm a superintendent - and make a point of telling the truth to my customers. Generally my HVAC guys put the unit where I tell them to - or we at least have a discussion about what is a reasonable location. If I happen not to be there when they arrive, they might put it anywhere they please... If a unit goes in the attic, they are gonna have to put it where ever the plywood platform has been built, but hopefully to one side of the platform.
Unless it is a walk up attic, it's likely not really built for much storage anyway (from a structural standpoint).
Well, I do live in a very, speccy home. lol and the only platform built was at the top of the attic opening, which is accessed via a very flimy trifold wooden ladder. I had thought about replaceing the attic ladder with a one-piece rigid unit, but because the attic access and 2nd floor zone AC/furnace are a) on the centerline, and b within 3' of each other I have to live with what I have.
Also, because the suspended the flex-ducts by cable and runs away from the AC/Furnace like an octopus one cannot venture very far into that attic, not even for simple low-voltage wiring (CAT5/Coax). In fact, the attic only serves as one purpose, to house the HVAC. It cannot be used for anything else. Not even storage, access to ceilings/walls, etc.
It would have been great had the HVAC been installed along the same location along the centerline, but just off the centerline 5-6'. I wouldn't imagine duct-runs have to change that much. And as a result, it would have allowed for better, or at least a more reasonable amount of attic accessability.
Your attic looks something like pics 3655 and 3656
and you want it more like 3657?
Ralph, thank you for making me feel like I am not alone! Yes, my attic looks exactly like the first two picture and much desires to look like that third picture. Did you do the work yourself, or did you get a mechanic company to straighten out that mess?
All, I find it difficult to believe that not be able to bring in a couple of 2'x8' strips of plywood and finding their own (talking HVAC person) desired location is deemed to costly or bothersome to afford a better install.
I am more inclined to believe that if it isn't in the code then its just laziness of the installer. There are other locations in the attic that would not have been above a closet, bedroom, or bathroom. Locating the unit at the foot of the ladder's top step seemed more passively designed to send the message: do not enter the attic.
Between the location of the AC/furnace and the overalll unwelcoming sense the attic portrays, its no wonder some homeowners don't even bother to clean or replace the unit's filters, which leads to other problems. Then again, I would not doun't this is a design, of sense, to produce work opportunity down the line.
I think I will call my favorite mechanical company that I've used in the past and ask them. I know they do service, repair, and installations on both existing properties and also in track housing first installs. If the code is open, hopefully they can explain just how 'open'. From there, I would see how much it would cost to make a change. I can live a winter without heating on that zone and this would afford an effort for a better change.
I should take some pics, too. I thought I had some, but can't find them at the moment.
If your attic framing can withstand the additional loading generated by installing usable floor space, such as shown in my pics, go ahead and move your unit.
There are no restrictions that I know of that would limit the placement of HVAC unless there are safety issues with a gas or oil fired furnace. If the code allowed a gas fired unit, such as the one I moved, to be placed in the attic in the first place, then there should be no particular location requirements other than clearance issues for maintanance and combustibles. Keep in mind that the HVAC in my area is, maybe 99.99%, heat pump, so I would definitely research the real code to resolve your questions.
Long runs of heated or cooled air can cause some loss of effectiveness but the benefits gained outweigh that consideration. Proper duct sizing for the volume of air moved is still required.
The filter replacement quandary can be solved by extending the air return ducting to convenient accessible locations and using the grills designed to hold replacable filters. Current code now requires return air from each room so the days of a centrally located return and filter are gone. In my area there are many, many retrofits in older homes that are going to be made more difficult and costly due to this new requirement.
FWIW, the attic in the pics gained over 1000sf of usable space. The plywood was screwed to 2x2 sleepers applied perpendicular to the existing joists and all the wiring, etc., easily routed or pushed around with no extra holes needed except for those needed in a few places to keep the junction boxes accessible.
The pull down stairs were already in the floor but, because this was an older home (1913) and a previous owner had oversized the hole for whatever reason, I was able to disassemble the standard width stairs, remove the treads and replace them with new, longer boards. I gained, IIRC, 4-6" in width which made access so much more comfortable. Now (then) I could unbolt the stair side and spring supports to allow the stair to hang straight down so I could pass the full 4'x8' sheets of plywood up.
I lived in an older home with the furnace in the attic. The home had a basement.One advantage of having the furnace in the attic was that it freed up space and made the basement much easier to finish.A disadvantage I experienced was that the furnace did not put out enough heat to heat the basement properly. I'm not sure if this is common (for the basement to be cold with the furnace in the attic)
With the houses I build if there are a few sheets of floor sheathing left over I'll have the framers put them in the attic - and there usually are and maybe a few half sheets too. Actually, I need a minimum of about 2 sheets if there is going to be an HVAC unit up there, one for the unit to sit on, and the other to supply the required access. This plywood would go next to the attic access which generally is in the center of the house to allow head head height and clear area on a trussed roof system attic. If there are more than a few whole sheets left over, they go back to the lumber yard for credit or is moved on to the next house to be framed; at ~$26 a sheet, it aint cheap. If a customer wants additional attic storage space, and trusses rated for lite stoarge (which are required) the upcharge is about $3.50 a sq ft. It's pretty much the same for stick framed as the attic floor joists (ceiling joists) need to be up-sized to 2x8s. In addition, this will normally require extra framing too as I like to raise the platforms at least 13" off the ceiling below to allow for plenty of insulation. Still, with a trussed roof system, the available attic storage is often limited by the truss webs (diagional braces).
Edited 10/10/2005 5:06 pm ET by Matt
I have read and worked to a dozen or so Mechanical Codes over the years and I have never seen such a requirement. Though I only have the most recent version of the IMC that applies locally, I can't say that I ever looked or had reason to look for such a requirement in any code. The "location requirements" include prohibited locations (hazardous, bedrooms, bathrooms, toilet rooms, storage closets, surgical rooms), protection from damage and volumetric / combustion air requirements. This covers the present versions of the International Mechancial Code (2003) anf the International Fuel Gas Code also 2003. I believe your 'super' may have interpreted the "code" without the text actually being present.