However you decide to accomplish it, I strongly recommend installing the HVAC components inside your conditioned space. There are pros & cons to each of these options:

10' Walls, Dropped Ceiling: This system gives you the versatility to place duct and tray ceilings wherever you want. The downfall is that you are building an entire framed ceiling system and will not have access to anything installed above the ceiling.

9' Walls, Tray in Truss: This is essentially the same as the previous option but limits your options for both duct and tray ceiling placement. If cost is the strongest driving force this option will be best.

Insulation at the roofline: Insulating the roofline gives you all sorts of space in the attic to place duct. Also, the ceiling height is determined by wither the truss tray or wall height giving you the most flexibility. The downfall is that you will be heating the entire attic, and this method doesn't allow you to use cheaper insulation options like blown fiberglass or cellulose. This is typically done with spray foam, however rigid insulation on the roof is also an option.

Best of Luck

I love 10" ceilings but hate dropped soffits running around them. The first thing people will say is "can I get rid of those soffit things on the ceiling if you ever go to sell. Your plan has merit, it does make sense and I've seen it done but in a different way with a little design change in roof trusses.

The designed trusses, called plenum trusses have a reverse bulkhead for HVAC runs built into the truss system. the tops of the bulkheads are sealed and insulated to bring the space into the thermal envelope of the house. You can have trusses built to accommodate almost any design you want, It just means the prices will be substantially higher. Lower ceiling here, higher ceilings there whatever. you're not off your rocker and it just takes good designing and engineering.

About 10' ceilings. People will rag on you how inefficient they are but ignore them. They're nice, the only thing I'd be aware of is the window and door sizes. 10' ceilings need taller windows or transoms to look good. 72" high windows really standout in 10' ceilings and anything less then 60" windows make the room look strange. Just keep that in mind.

Locating ductwork in conditioned spaces is desirable, but uncommon, in my experience.

You might consider ductless mini-split heat pumps in lieu of ducted options for air conditioning. A ductless system eliminates the costs and drawbacks of ductwork and you'll have multi-zone temperature control.

From a cost standpoint, I think you'll find it more economical to construct your home with 9 ft ceilings and bump up the ceiling height to 10 ft only where you need it.

You'll be well served to consult residential design and construction professionals early in the design process.

Thanks for the responses! I am pretty early in the design phase, so I still have a lot to think about. Just trying to get some initial ideas to design around. I will try to map out where I was thinking about running the ducting and what rooms would have the drop ceilings.

We had something similar in a basement. One room had a tray that was partly filled with ductwork. A closet had 8.5 ft ceilings that had some ductwork. And there was a part of the theater room with a dropped ceiling. It can be done but may not be the best way.

If you really get into the weeds, you will probably build a tight house. Then, you will find the need for in floor heat becomes lessened. At some point, the floor doesn't feel all that warm in a tight house. And boy, it adds some cost.

The taller the ceilings the more heat and cooling you need. Sure you can build tight, but that can introduce more problems... air quality, humidity, odors.

Pull the duct work into the envelope all well and good if it's sheet metal duct. But then you need a well thought out place to put the HVAC system components not only to repair but also replace at some point. That's going to take valuable floor space in a RE market that is over priced already most areas.

Mini splits solve one problem but leave you equipment poor when it comes to maintenance and eventual repairs and replacements. More equipment = more money, more problems.

You can argue 9 ways to Sunday which is the better way to do this or that but they all have consequences.

A solution is a solution because it doesn't create new problems. Otherwise: It's not a solution.

A house... no matter how well thought out, how well built, designed etc. They all require maintenance, upkeep, repairs etc.

After about 10 years (maybe less) all new homes start breaking. KISS is often the best method. That is 26 years of experience talking. Fixing the homes I own, and the ones I don't own.

Build tight, ventilate right. Takes care of IAQ issues. And don't forget, it often smells more outside and it certainly has higher humidity outside sometimes.

Hi, Walleyemn,

Design is an optimization exercise that seeks to balance a number of constraints. I think you'll open up more design possibilities if you shift your focus from how to keep ductwork inside a conditioned space to how to eliminate the problems associated with ducts in unconditioned spaces (e.g., energy losses, potential for condensation, mold/mildew, etc.)

I suggest avoid installing flexible duct work in the attic. With some good planning all the duct work should be installed inside conditioned space. You also should have to install drop ceiling if the duct are running parallel to joists. In may area new 9 foot ceilings on the first floor has become common.

Have you determined where the HVAC equipment will be located? The center of the house would be the best. If it is going in a utility closed make sure it is large enough for access for servicing.

Lots of good info here.

Originally we were planning on a barndominium design. That idea has since changed, but the thought of one solid roofline has kind of stuck. Primarily for cost reasons. It is however becoming challenging to lay everything out the way I want it in a rectangle box so to speak.

While I don't mind the looks of hip roofs and multiple rooflines, I would like to stay away from that due to cost, more valleys = more chances to leak, etc.

As stated before, we are still pretty early in the design phase. My wife and I have finally come up with a few floor layouts that we can agree on, so getting closer. One of them we both really like, but it puts the mechanical room off to one end of the home. At what distance should one consider changing the layout and trying to centralize the mechanical room? is an 80' run of duct out of the question?

At what distance should one consider changing the layout and trying to centralize the mechanical room? is an 80' run of duct out of the question?

How is the control going to know what the temperature is 80 foot away in another room / area of the house?

You can zone areas... but that isn't as simple as it sounds. Remember a *real* solution doesn't create new problems. There are more ways to zone a house... with equipment, with controls. Each have their troubles.

So you move the control to this area 80 feet away. Now it's too cold or hot in the area that you moved the control from. (new problems)

Humidity doesn't get into tight structures: You have people in those structures that talk, eat, shower, clean clothes etc. All of which produce humidity. That spells trouble for a tight structure because it's tight. Again a solution that doesn't create new problems? Otherwise not a solution.

Certainly ventilation can help... but that can also cause more problems. We're talking solutions aren't we?

A builder doesn't care. They build. They build. They build. You are going to live here for what 30 years? How long will it be until you have grown tired of dealing with GC's and builders.

I'll tell you... about a year. Now due to choices your builder made and you made with them you more times than not are strapped to a 'rectangular box'. What seemed wise at the time of building turns out to not be so wise.

Remember, I have been in thousands of homes. Thousands. I don't build. I fix. (not people or their perceptions)

I definitely plan to zone the house. Our current home is a split level and the original owner only installed one thermostat on the upper floor. So no matter the season, it's 68-70 upstairs and about 60-62 downstairs. Great for sleeping, but would be nice if it was more balanced.

Also plan on an air exchanger of sorts since the house will be built fairly tight.

trying to get as many ideas as I can now, so when we do sit down to finalize things, changes are minimal.

Moving air 80 ft is an issue of ductwork design and equipment selection. You can be perfectly comfortably with a system controlled by a single thermostat provided that all of the spaces have similar heat gains/losses and the airflows to the rooms are properly balanced. Neither are typical. For multi-level homes, zoning is a way to deal with the differences and ensure occupant comfort on each level.

You will find builders who care about every aspect of the homes they build and even some who have designed HVAC systems. Seek and you will find....

You can be perfectly comfortably with a system controlled by a single thermostat.

I'm living proof that you can't. In fact it's a quite common problem where I live.

So you mean to tell me that people have been making this problem up in there heads for the past 26 years?

Who you gonna call if you have a problem like that? a builder? ha ha.

Builders build then build some more, then some more, then some more. They never look backwards. Ask me how I know.

They will build houses with 20 and 30 foot tall ceilings. Walls of glass windows. These things aren't to make you comfortable --- they're there to sell you on it. In a years time, the warranty runs out. The builder isn't coming back. They build. That's it.

Haven't seen a builder yet that doesn't cut corners some where. Been in million dollar homes, which are rare here (mega mansions) it's no different. Troubles, troubles, troubles.

When those happen... a builder does not get called. C'mon man.

@Austin Air Companie,

You've taken a phrase of my post out of context. That changes everything. Just like with instructions, you'll be well served to read it completely. I stated:

You can be perfectly comfortably with a system controlled by a single thermostat provided that all of the spaces have similar heat gains/losses and the airflows to the rooms are properly balanced. Neither are typical.

There is no period after the word "thermostat" that would make it a simple declarative statement. The modifier "provided that all of the spaces have similar heat gains/losses and the airflows to the rooms are properly balanced"and the following sentenceprovide important context.

I believe you are a service-only HVAC contractor. It makes sense that your experience base would include mostly, if not exclusively, problem systems. In my engineering career I designed a wide variety of HVAC systems for commercial and industrial applications. For more than two decades I've collaborated with my HVAC contractor on the design of the HVAC systems in each home we've built or remodeled. And I've consulted with others on problem systems. And yes, I get the calls from my clients if they don't work as designed.

It may be fun to beat up on builders, engineers, architects, lawyers, etc. but like any profession, they include a variety of individuals with varied competencies in their field. I've remodeled homes where the original HVAC system was designed and installed correctly, some where it was designed incorrectly, installed incorrectly or both. I'm set to begin remodeling of a home where the HVAC system appears to have been installed correctly at original construction and subsequently butchered by one or more HVAC service/replacement contractors.

To many drinks at hooters across the street Ray? Yes you cherry picked the statement from Charles, something you'd see on MSNBC. I understood it, but my question is to the OP, will you use a segway to travel from one end to the other of that 80' house? I have a 70' deep garage and get winded going back and forth for a tool.

LOL.

Sure I cherry picked. People call me with problems. The world turns. Thermostats control temps around them maybe 5 - 10 feet. I state facts... builders build, build, build. I guess you could say I am beating you? LOL.

The discussion here was 80 feet. Balancing is a "good excuse"... the weather changes balancing is out of balance. (heat rises / cooling falls type problems) Mild climates don't give you problems like I got. People have different ideas what comfort means.

Now mix in what I also said above... walls of glass, high expansive areas --- 10- 12- 15- 30ft high.

So what I said... whether you like it or not... when you read my context what does it tell you?

My phone will continue to ring with problems. Builders will continue to build. I do what I do, you do what you do. If that sounds like a whipping... well? It's a good laugh for me.

Take it how you want it.... (the truth often stings, when you try to ignore it)

PS: I haven't been to Hooter's since I've lived here even though I could walk there. I don't drink. I run two businesses HVAC and home rental business. When would I have time to drink?

@Austin Air Companie

You've made it clear that you're not a designer or installer of HVAC systems; you're a service contractor. Your post certainly provides corroborating evidence. If there's a question about HVAC design, you'll be doing houzzers a great service to reserve the posting space for folks with relevant expertise.

There's plenty of bad information here on houzz.com It's embarrassing when it comes from "professionals."

I probably should have mentioned that the plan for this house is to be Handicap Accessible. Not 100% to start, but with every intension of converting it when the time comes. My wife has a form of MS and with this being our "forever home", we want to set the stage for a wheelchair if/when that happens.

I am installing wider doors from the get go. not just for HC accessibility, but for moving furniture. Boiler plates in the wall for grab handles down the road. etc.

With that being said, the house is being oversized by design. The layout seems to get tweaked daily. Original plan was going to start out as 36x72 with an angled attached breezeway and 3 stall garage. this is where the 80' run of ductwork came in as the mechanical room was going to be in the breezeway.

For many years I built homes with contractor designed HVAC systems. These systems were mostly successful, and my customers seemed happy. Then about 2 years ago I ran into an HVAC design firm that blew up my understanding HVAC. I wish I had known what I know now! PROPERLY designed HVAC systems are super beneficial to the life and comfort of a home.

I also found that even if the design is done properly, the install may not be. Especially concerning balancing. I have the design firm I use come and test things after install to ensure proper seal and balance. Even on low-budget projects I firmly believe in this process. I'm currently bidding a $250k project and will happily pay a $2,000 design and test fee.

@D B

Choosing builders based on competitive bids is how many homeowners end up with HVAC systems designed, installed, and serviced by "Chuck in a Truck." You're doing the right thing, delivering a better home and your likely to lose a lot of jobs because you'll be deemed "more expensive."

I once asked a contractor why he charged so much and he smiled and said; "when I charge twice as much I get half the jobs but make the same money." Odd but true, and I always wonder about the "Best job at the cheapest price in town!" advertisements. Are they the best and cheapest, not usually. "Two men and a Truck" did well, why not chuck?

I'm currently bidding a $250k project and will happily pay a $2,000 design and test fee.

The elephant in the room.... $2000 before anything else happens = very small market UNLESS you are building a new home. Otherwise it's not likely for someone that plans to move in 5 or 10 years --- which is pretty much the average here in my market. (Katy, Texas area)

What I do most people will not do. Most = 99.9% It's not a glamourous job. It kicks my hiney to the curb (when I do more than just a minor repair) Every muscle in my body aches. Spasms after the fact. I know my days are numbered to do what I do. I was just reminded of this last night.

The biggest thing why people use me: Is #1 I am honest. If someone wants a repair, that's what I attempt to do.

Where I live: People come here to work. It's not common to find a lifer here that doesn't plan to move. The weather, the bouts of calamity like hurricanes and power outages or some other tragic event. It's not like any other place I have lived.

---------- so back to the 80 FT Run -------------------

If you live in a 'moderate to mild' climate --- probably very little concern with a longer than *typical* duct run.

I don't live in a mild climate -- like Mr Fudd who can afford to wait for 6 weeks to get something done. I live in a hot climate the exact opposite of a cold climate like Chicago area where I lived before. Different climate different concerns.

BUT an 80 foot run will have issues with a single thermostat in an *extreme* climate. A thermostat placed 80 feet away in a different area can not know how hot or cold it is in an area 80 ft away.

A mild climate changes that.... You can argue that keeping areas balanced with the same or similar loads to balance a system. BUT people are people... they often do and use properties in ways in which you can't imagine from a piece of 'design paper' --- that is where I come into the picture. (Or so I think, that and not wanting to replace everything anytime the system breaks.)

We'll have a run that's over 110' - but....

• it's entirely within conditioned space
• it's entirely done in rigid spiral ductwork
• it's going to be zoned with appropriate dampers
• there's a lot of volume in open area with 2 low velocity / high volume fans going

With the right HVAC designer and installer (or full service company - preferable) there's no reason you can't be comfortable in your home.

I'll also contend that even climates that are not "extreme" (and I consider my NC climate 'moderate') there are always load challenges from the setting sun, or other orientation issues, My master bedroom is on the west end of the house - it will require much more AC going to it in the evening, and, likely solar screens for the large windows in the summer. All things that can be managed.

One last note on the continued recommendation for mini splits - I think that sometimes people forget that there are fans / condenser units that have to be put outside that go with each of the head units that stick on the wall. They all require wiring, etc and get pretty unattractive outside if you need several - not to mention that they are not all that attractive inside and don't distribute air outside the "room" they are in because of the ductless aspect. I'll use one for my garage for example -but don't want them in 4-5 rooms in my house....

I'll also contend that even climates that are not "extreme" (and I consider my NC climate 'moderate') there are always load challenges from the setting sun, or other orientation issues, My master bedroom is on the west end of the house - it will require much more AC going to it in the evening....

Yeah I would agree. Really for the reason that no two people think of comfort the same way. It's not uncommon here (Katy, Texas) for people to fight over what temperature the thermostat is set at.

It's a very common question... what temperature should we set the thermostat at? Design temps here are 75 inside / 95 out. People move here from northern areas and 75 is too warm. So you're trying to cool an area to 70 degrees in which it was designed for 75. When it's mild outside usually no problem. But I'm called to homes occasionally that can't even do that. My climate, my area, my problems.

That's what this business is built upon. Problems. You're gonna have them at some point. More mild it is in your climate maybe it takes 20 years?

You can design a home for a lower design set point here... but now it's oversized when considering normal design methods. Due to humidity here.....

Throw in 80% or higher humidity and you've got more problems you can shake a stick at.

Location, Location, Location. Then what does comfort mean to you.

@Austin Air Companie,

A thermostat placed 80 feet away in a different area can not know how hot or cold it is in an area 80 ft away.

Duh. It is not the job of a thermostat to sense the temperature 80 ft away. A thermostat should accurately sense the temperature in the area in which it is located. It is the job of the HVAC designer to specify the location of each thermostat so the measured temperature is representative of the environment it controls. Where the heat gains/losses of the spaces are similar and air flows are balanced to design values, a single thermostat will suffice. Where heat gains/losses are different, a zoning approach with multiple thermostats is indicated.

You can design a home for a lower design set point here... but now it's oversized when considering normal design methods. Due to humidity here.....

What set point? Temperature? Humidity? Air velocity? What design methods? Temperature control and humidity control are separate, but related, design criteria. Achieving a lower dry bulb temperature doesn't necessitate a higher relative humidity in the living space; it depends on the design of the system--which may contain multiple components-- and that's what HVAC designers and engineers are for.

That said, I'm sure the folks around Katy, TX appreciate freon-breathing service contractors like you. They just shouldn't seek HVAC design advice from them.

Duh. It is not the job of a thermostat to sense the temperature 80 ft away. A thermostat should accurately sense the temperature in the area in which it is located. It is the job of the HVAC designer to specify the location of each thermostat so the measured temperature is representative of the environment it controls.

So in other words when the area that is 80 ft away and too hot, you can then say duh to the customer / prospective homeowner?

You'd be surprised how many times people have requested me to physically move a thermostat not realizing that simply moving it will create "NEW" problems. (colder in other areas relative to the new area it was place in.) IE: a solution is one that doesn't create new problems. Otherwise not a solution.

Oh let's add sensors to various rooms... same difference. It's going to keep pumping air and try to magically create comfort. There's every kind of garbage contraption you can imagine. I've had to stop people more than once, maybe more than a thousand times from making a dumb mistake. Some listen, some think they know everything even when what I do isn't what they do.

I often tell prospective customers that if they think they know more than me... they don't need me. I am not a third wheel that is going to get dictated to. Been doing this for over 26 years. Had more than my fair share of disagreements with engineers, while some actually listen to what I say.

Your climate in Virginia entirely different... different climate different concerns. Your cooling season is short. Mine is nearly always 10 months long, sometimes longer.

I've heard every excuse in the book when it comes to builders. I can't say they've ever used DUH as an excuse.

The design sheet doesn't know what that room or rooms 80 ft away is going to be used for. Does the thermostat know? (I'm in the home when people are actually living in it.)

PS: humidity control... real humidity control is another separate system that is best tied to a humidistat. That system is in addition to your air conditioner, requires maintenance and up keep, repairs and eventual replacement. More money. More electrical cost on the light bill. It's a separate system tied to the HVAC system.

An air conditioner does not "control" humidity. Remember I said HVAC market was built on problems. In my market it's not just what humidity is created in the house, it's also humidity that makes it into the house in a humid climate. A very humid climate (Katy, Texas)

Technology has made better inroads into helping with humidity via Inverter AC's and the ability to modulate up and down. But these systems run off temperature, not humidity.

I'm sure you're well aware that you can have high humidity at lower temps. But these comments that I make aren't for you wise guy... They are for the people who read these threads months, sometimes years later that are searching for someone like me.

I know my lane, now you know yours. Stay in it.

George Carlin famously said "Never argue with an idiot. They will only bring you down to their level and beat you with experience." I think this pearl of wisdom just might have been inspired by a service call for his HVAC system.

There's truth in that if we can agree on anything... Another way of saying it is don't cast your pearls before swine.

But, this is a forum board casting light on various things that others will read. It's not just a conversation between you and me. (Otherwise there would be no point to it.)

You're not my customer. A builder is merely an indirect way for me to obtain a customer.

Builders build. You're not suited to do what I do, I am not suited to do what you do. The market is plenty big for both.

So why would I post in a new build type thread? Highlighting potential pitfalls is all. It's not my customer base until after a couple of years anywhere from 2 to 3 years usually after the builder is long gone.

I don't do new construction jobs. Not my lane. Just pointing pitfalls is all.

Charles Ross Homes, another old chestnut that may apply is "If all you have is a hammer, everything looks like a nail".

And I'll add to that - and all you can talk about is nails.