Help with all new HVAC / ducting design process in a unique rehab

bryantroll

Hello HeatingHelp forum friends, my favorite place to research and ask questions about my HVAC planning. I'm still a novice, but trying to learn as much as I can along the way. Thank you for entertaining my questions...

I am rehabbing a concrete dome house that has early 80's hydronic in floor heating which has numerous issues and is being retired. With that said, I am starting from scratch on a new heating and cooling design for the home. I have considered all options out there but at this point am pursuing a ducted, forced air system.

I have someone who can install the system for me, but I would like to make sure the design is correct with regards to Manual J, S, D first. I just wanted to check to make sure my process is correct:
1) Am I correct to start by figuring out the Manual J, S, and D?
2) If I do the legwork, can I just calculate these things myself or does it go beyond the abilities of a dedicated DIYer? Or possible DIY this along with the help of someone on this forum?
3) I have found a couple local companies that do Manual J, S, D -- is about $1000-$1200 correct for all of these in a 3500-4000 square foot home?
4) Do they come on site to understand the quirks of the design, or is all of the work done remotely? With that, should I be hiring a local specifically or not worry about that?

*Bonus Question*:
1b: I am trying to maintain as much headroom the basement which is where the main ducting trunk will run -- is it reasonable to keep the ducting height to 4"-5" and just allow it to be 30"-35" wide? I am planning for two zoned supply trunks and one return trunk which would run across the ceiling of the two basement bedrooms. Current ceiling height is about 90" and I'm trying to avoid bringing that down to an entirely uncomfortable height if I can avoid it.
2b: As there are no current provisions for ducting and I am trying to minimize the space impact from running ducting, I have researched various options: ductless mini splits, high velocity, Rheia, and more. I keep coming back to a traditional ducted system as the safest play... any opinions or ideas on the best system that balances function and reliability along with minimizing design impact on the home?

edit: sidenote: Avg ambient temp has been 80-85 degrees as a high and 60 at night the past couple of weeks. With 0 conditioning inside and all windows closed, inside temps have consistently stayed at 61-62 degrees in the basement, 68-69 degrees on the main floor, and 71-72 degrees in the loft.

Link to floorpans, if it helps. Mechanical room located in basement, and main trunk would run just inside basement bedroom walls. Glue Lams run left to right, floor joists up and down. https://drive.google.com/file/d/1oENdko8pVpFBd3yQ8E3fgoH9CH-JWxdH/view?usp=share_link

Hot_water_fan

2b: As there are no current provisions for ducting and I am trying to minimize the space impact from running ducting, I have researched various options: ductless mini splits, high velocity, Rheia, and more. I keep coming back to a traditional ducted system as the safest play... any opinions or ideas on the best system that balances function and reliability along with minimizing design impact on the home? 

Cool house! 

Ducted is a great balance in my opinion. You may find a ductless unit or two will be necessary, but stick with ducted for as much as is feasible. 

For the basement, if the heat and cooling loads are low enough, some electric baseboards might be the best option - cheap and could save you some head room. 

bryantroll

Thank you!
I figure that the main trunks will run along the basement ceiling and I can just go vertical from there into the main floor and loft. The vents would be in the ceiling of the basement and in the floor of the main floor, and then there are 2 or 3 small chases I could utilize to get 2 supplies and 1 or 2 returns up to the loft. If thats how I do it then removing ducting from the basement only has limited gain since it would require the main supply/return running across the basement regardless.
Also I always figured that electric baseboard would be much more expensive to operate than natural gas (or a heat pump). Is that not correct?

also, edited the first post to add:
edit: sidenote: Avg ambient temp has been 80-85 degrees as a high and 60 at night the past couple of weeks. With 0 conditioning inside and all windows closed, inside temps have consistently stayed at 61-62 degrees in the basement, 68-69 degrees on the main floor, and 71-72 degrees in the loft.

Hot_water_fan

If thats how I do it then removing ducting from the basement only has limited gain since it would require the main supply/return running across the basement regardless. 

The goal wouldn’t be to eliminate the ducting in the basement, rather you’d need small diameter ductwork since the ductwork needs to move les
fewer btus. 

Also I always figured that electric baseboard would be much more expensive to operate than natural gas (or a heat pump). Is that not correct?

That part is correct- but that’s not always relevant. Install cost also matters - if some limited areas don’t need much heat, paying more to heat them can be better than the cost of getting a more efficient heat source to them. It’s a balance. 

bryantroll

Well -- IF its possible to go with 5" or 6" tall main trunk ducting at the most, then I will likely just drop the entire bedroom ceiling down so its even and have the ducting run across there. That would still give me roughly 7' of headroom and no real drawback to having the ducting for the basement there as well. Just trying to avoid bring it down too much more than that.
Does anyone know if this is possible? I know getting too oblong in duct sizing isn't ideal but is it reasonable to go to something like 5"x35" for each main supply and main return?

I think at this point I'm really just looking to figure out some of the questions I posted above with regards to the correct process to plan and execute this -- who to reach out to about manual J/S/D and if a local's price of $1100 is reasonable vs the non-local companies offering to do it for about $600.

Hot_water_fan

We don’t discuss pricing, so you’re on your own for that part. I’d go with the local based on proximity. Manual Js aren’t usually very accurate, so if you have a winters worth of fuel usage, I’d go with that to at least check the manual J. 

clammy

Don’t except great air flow out of a 5 x 30 duct there’s some basic rules to follow when it comes to air flow and duct work . Never go more than 2.5 times your height so say a 6 x12 and u ain’t moving a lot of air through that . If you’re worried about duct height and size what are you planning to do with a return duct pull air right from the basement.
I ve seen plenty of jobs where people attempt to do the same thing squeeze duct to extremes and wonder why it works like garbage . It s usually difficult to maintain a high ceiling in a lower ceiling height basement and have proper sized duct work and a system which is quiet and operates properly .
You need to have a decent main trunk line sized to move the needed cfm of air equipped w dampers to adjust air flow ,trunk line should be reduced as the duct progresses . Your return duct should be pulling air from the conditioned space not from the basement . After all your load Calc are in your going to need some one w experience to lay it all ,there’s gonna have to be little give on the height issue verses proper duct design .
Are you using the existing chimney assuming you’re going to do a gas furnace and a coil w a new outdoor unit . Possibly looking into a 2 stage gas furnace tied up w a Bosch inverter heat pump and indoor coil . Especially if you have to run electric any way for the condenser.
In closing chose your contractor wisely .
Peace and good luck clammy

bryantroll

Hot_water_fan said:

We don’t discuss pricing, so you’re on your own for that part. I’d go with the local based on proximity. Manual Js aren’t usually very accurate, so if you have a winters worth of fuel usage, I’d go with that to at least check the manual J. 

Unfortunately I don't have any heating history other than I used two 1500w electric space heaters to keep the house at 50 degrees this past winter. Think I'm starting from scratch.
Do you believe that paying for a manual J / S / D is a good idea, or something I can do just about as well on myself?

clammy said:

Don’t except great air flow out of a 5 x 30 duct there’s some basic rules to follow when it comes to air flow and duct work . Never go more than 2.5 times your height so say a 6 x12 and u ain’t moving a lot of air through that . If you’re worried about duct height and size what are you planning to do with a return duct pull air right from the basement.

I had planned to have 2 supply trunks and 1 return trunk run along the basement ceiling, which would serve the entire house. The vents would be in the ceiling of the basement and the floor of the main level, and then I would use a few vertical stacks to get supplies and returns to the loft area. This would allow multiple returns on each level as well, including the finished conditioned basement as well the main floor and the loft.
The basement ceiling height after flooring and drywall will be about 90", so if I go with an 8" duct height it will being me down to 82" -- or 6'10". Code requires finished basement height of 7', or 6'6" under ducting/soffits. I'd just really like to conserve as much ceiling height as possible to keep things feeling comfortable.
Calculating it out, an 8"x22" (176 sq in) duct would have roughly the same flow as:
7"x26" (182 sq in)
6"x32" (192 sq in)
5"x42" (210 sq in)
4"x59" (236 sq in)
I should have the width to spare, just trying to find the best option for height. Hoping that 6" of height is acceptable then? I'd really like to keep ceiling height at 7' if at all possible. If the right choice is to go with 8" tall ducting then so be it -- just trying to investigate all options so I can make an educated decision.

clammy said:

I ve seen plenty of jobs where people attempt to do the same thing squeeze duct to extremes and wonder why it works like garbage . It s usually difficult to maintain a high ceiling in a lower ceiling height basement and have proper sized duct work and a system which is quiet and operates properly .
You need to have a decent main trunk line sized to move the needed cfm of air equipped w dampers to adjust air flow ,trunk line should be reduced as the duct progresses . Your return duct should be pulling air from the conditioned space not from the basement .

The point I'm at now is to determine the best ducting size for my project -- do you think that hiring someone to calculate a manual j / s / d is recommended for this? I hear mixed opinions on whether its something you can just calculate yourself or not, especially since I have the layout mostly worked out myself now.
Trying to line out the next few steps to determine duct size, equipment, and where to go to have ducting made.

clammy said:

After all your load Calc are in your going to need some one w experience to lay it all ,there’s gonna have to be little give on the height issue verses proper duct design .

Would this be an HVAC installer or a mechanical guy who just does Manual J/S/D? I was surprised that basically all of the installers who came out said they could bring their Manual J guy on board to do the planning -- I thought I was talking to the people doing the planning! I can just go to a "Manual J guy" myself if thats the case.

clammy said:

Are you using the existing chimney assuming you’re going to do a gas furnace and a coil w a new outdoor unit . Possibly looking into a 2 stage gas furnace tied up w a Bosch inverter heat pump and indoor coil . Especially if you have to run electric any way for the condenser.

I will have a gas fireplace on the main level using a chimney. There is also a chimney from the basement from an old wood burning stove that may not be reused. I was hoping to use a high efficiency gas furnace and run the PVC piping outside from the mechanical room to handle intake and exhaust.
Another thing I have to watch is how much available space I have in my mechanical room to make sure its sufficient for both a furnace and heat pump / AC unit.

clammy said:

In closing chose your contractor wisely .

This feels like the impossible task -- I have had a handful of contractors out for a site visit and 0 calls back or follow up. I don't understand why they waste their time coming out at all and certainly not someone I'm interested in hiring if they have 0 followup.
I am not against hiring someone who will come in and do a great job, but all I see so far is below average guys and at that point I'd rather do it myself. I'm still looking though, hoping to find some great people to work with.

clammy said:

Peace and good luck clammy

Thanks! Really appreciate your input on it all.

clammy

I know I would not even think of doing a job where the there’s not enough room to fit any duct work ,why do a job that not only is going to be tight but at a 8 x 22 duct I hope they use bar slip to prevent the duct from expanding and making noise aside from cross breaks when ever the fan comes on . Most ac guys are not going to widen out ducts for ceiling jobs in basements at least not me ,I know what’s possible and what works and I know what does not work and I stay away from those jobs at my age I’m done trying to re educate and I give them what they want and in no clear terms it what they wants being most have decades of experience behind them aside from a ductalator .
That basic rule for duct 8 inch would 16 inch so 8 x 16 as you go wider your air flow is less round being perfect and the further from square you go the more static and more restriction and less flow . 8 x 22 is a stretch again all that straight duct will have to have a cross break to stiffen and personally I would use bar slip to stiffen it up . I hope your no getting it lined this will further decrease the internal diameter and by wrapping if done w real duct wrap not bubble your gonna lose some more height . Personally I would also walk away 1 I’m to old to waste my time w some one who wants every square inch of a home useable ,I feel if you want all the space then get window units and possible a hot water boiler or just go all electric .
In closing do a crap job on your duct work and let your ceiling height determine everything usually from my experience and what I seen over 35 to 40 years you will end up w crap and have issue no one will ever make it operate completely properly and you will have even a harder time finding anyone willing to do anything except rip it out .
I some times say to myself thank god I m closing in on the end cause i would need a couple of lifetimes alone to straighten out all the garbage I see and that others call properly installed . The amazing drag race to the bottom and end of the line . All this stuff is nothing any one can figure it out and do it until the lack of experience slap ya in the face yeah it ain’t so easy . Real mech don’t waste there time w nonsense and illogical non mechanical thinking they move on to real work that money can be made at not splitting a inch for a inch
in ceiling height they have far better things to do . Most real contractors don’t waste time figuring out some thing that they are not going to get and that is going to a total hassle and future issue that there left holding the bang it’s not smart business practice plan and simple .
For a start be realistic and realize your not fitting 10 lbs of Pooh in a 1/4 lbs bang ,there’s no duct
Not all contractors or business operate the same so don’t thing it’s all the same quality and workmanship like a snow flake no two contractor are the same and neither is there work
possibly the same lip service though .
Peace and good luck clammy

EdTheHeaterMan

Have you considered a High Velocity air handler? A 8" or 10" round duct around the perimeter with 2" takeoffs throughout the building might work out with great success.

I also believe they are more forgiving with return air.
you could locate the air handler in the utility room to the plenum/trunk on the basement floor. A single, central return could come from a central location on the main floor.

The heating could then be from a heat-pump of a gas boiler. There are options.

EdTheHeaterMan

Here is the beginnings of a High Velocity system design. Some additional details. Depending on the size you may be able to use an 8" round metal pipe for the plenum. With a sheetrock soffit you should be able to stay less than 12" in the corners of the rooms and still be above the doorway transom within less than 18” horizontal overhead.
This is the brand that installed
https://www.unicosystem.com/products/
There are others that may be available locally. I believe SpacePak is available thru Granger if there is one of those near you.

bryantroll

Clammy, thank you again for taking the time to reply.
I am trying to do my research and learn -- one HVAC contractor suggested an 8x22 duct as a rough estimate for a supply trunk which is what I was working off of. I do not know the duct size required, but I can tell you that online calculators spit out the sizes I posted above, which are each oversized more and more as the height gets shorter. They may have more loss, but they are oversized to offset that which should, in theory, allow for the same airflow.
I can certainly understand if you would choose not to take a certain job, thats totally fair, however I would challenge that a "real mech" as you say wouldn't just say "no" to a job that has challenges, if they are truly good then they would work to find the best solution. If you have any suggestions on what the best solution would be to add functional ducting to the basement of a home where the basement is a finished apartment and needs to be reasonable living space so head room is an important component, I would love to hear your thoughts. I have considered mini splits, high velocity, Rheia systems as well, and maybe there are even more. None are perfect, including traditional ducting. I was just hoping that traditional ducting was the most well rounded solution if I could manage the ceiling height impact in the basement.

EdTheHeaterMan,
Thank you for taking the time to reply. I did look into high velocity a bit -- I talked to one contractor who seemed to have some experience with it, but he never followed up with me (no one has!). I don't know enough about it to make a decision but maybe I should circle back on that option. I know its louder which is a bit of a drawback for me but I understand that some compromises will have to be made one way or another here. I was also recently clued into the Rheia system but have heard more criticism on it than praise, but likely from people who haven't worked with it and are just judging it from the internet.
As far as returns go, regardless of the system I should have a very easy, short path to place a return in the basement right through a wall of the mechanical room, and I can also do a short return run up through the basement ceiling to the main floor as well. This simple setup would allow me to avoid a main trunk line running across the entire house completely, but I had been directed that I needed more returns than this, and that I should also have a return in the loft to help circulate some of that warmer air up there. I will have a ceiling fan which should help, regardless.

Seems like I have some more research work to do here, unfortunately... I am so trying to get to a point where I can commit to a decision and move forward! Hopefully soon...

EdTheHeaterMan

Installed correctly they are very quiet. I remember getting a client with a poorly installed Unico System. The original installer did not install the Sound attenuating duct runs for the last 4 feet of the supply runs. As a test I replaced two of the supply ducts going to a bathroom with the proper material and let the customer hear the difference. He approved replacing 2 more rooms (bedrooms). Once the wife heard the difference, I got the job to replace all the duct runs on a 4 unit system in the entire home. That was an 8 day project and they were loyal customers with maintenance agreements on all the Equipment including 4 condensing units, 4 air handlers with hydronic coils and a boiler. Don’t worry about noise. What I would do with the long return duct and the proper supply ducts you will hardly hear a thing. No more than a standard air handler or furnace.


Try the “find a contractor” on the manufacturers site. If you don't get a response from their recommended local contractor then call the manufacturer and ask why they don't want to sell you their system? Sometimes that will spark the local business owner to get back to you.

This equipment is more expensive so you may be looking at 50% to 80% more for the job but it will work better and will leave you all the headroom you need. I find the High Velocity air movement in the home will reduce stratification of the different temperatures on each floor. (the first floor and the basement will be closer to the same temperature)

bryantroll

Thank you for your input on that. Someone had stated that high velocity is better for AC than for heat because the speed the air flows loses heat more quickly, but I have no idea if there's any truth to that. I will do a deeper dive on high velocity systems (but am a bit worried about total system cost).

Any opinions on mini splits throughout the house? 1 per bedroom plus 1 in the common area on each floor? Possibly supplement with electric baseboard heat if/when the temp really takes a dive? This would be a 4 zone system for the main floor/loft and a 3 zone in the basement.
I'm just trying to keep all options open since there doesn't seem to be one stand-out solution.

Hot_water_fan

Any opinions on mini splits throughout the house? 1 per bedroom plus 1 in the common area on each floor? Possibly supplement with electric baseboard heat if/when the temp really takes a dive? This would be a 4 zone system for the main floor/loft and a 3 zone in the basement. 

This is the worst option and should be the last resort. The ductless manufacturers themselves advise against this! The bedrooms will be too small for each to get its own head. 

The gold standard is ductwork. 

Larry Weingarten

Hi @bryantroll , I know what I'm about to say will seem off topic, but if the heating/cooling load were less, you could install a smaller, easier to fit system. So, have you done everything possible to reduce loads? Have you done blower door testing, and air sealing? Have you insulated more than most people think is needed? Energy prices keep going up faster than inflation: https://www.in2013dollars.com/Energy/price-inflation , so consider Insulating for future prices, not just the current price.

Yours, Larry

bryantroll

Hot_water_fan said:

Any opinions on mini splits throughout the house? 1 per bedroom plus 1 in the common area on each floor? Possibly supplement with electric baseboard heat if/when the temp really takes a dive? This would be a 4 zone system for the main floor/loft and a 3 zone in the basement. 

This is the worst option and should be the last resort. The ductless manufacturers themselves advise against this! The bedrooms will be too small for each to get its own head. 

The gold standard is ductwork. 

Sigh, it feels like every direction I turn has a fatal flaw. I honestly don’t know which way to go here.

If these were my asks, what would you suggest?
1) heat needed, AC needs are minimal but it would be ideal to have both upstairs. 
2) not entirely compromise ceiling height in basement bedrooms where traditional ducting would need to run (ceiling being currently at 90”)
3) budget is a consideration but not the only consideration 

I’m really trying to find a path forward but feels like I’m not making progress toward a decision 

Hot_water_fan

If these were my asks, what would you suggest?
1) heat needed, AC needs are minimal but it would be ideal to have both upstairs.
2) not entirely compromise ceiling height in basement bedrooms where traditional ducting would need to run (ceiling being currently at 90”)
3) budget is a consideration but not the only consideration

1. Not much of a concern - adding cooling is cheap. No need to stress about this one. Ductwork/ductless can heat and cool.
2. The duct size is driven by heat loss calculation - nail that down. If heat loss is too high, reduce to get the ductwork smaller or target some rooms for non-ducted heat.
3. Sympathy there, your options aren't exactly cheap.

bryantroll

Larry Weingarten said:

Hi @bryantroll , I know what I'm about to say will seem off topic, but if the heating/cooling load were less, you could install a smaller, easier to fit system. So, have you done everything possible to reduce loads? Have you done blower door testing, and air sealing? Have you insulated more than most people think is needed? Energy prices keep going up faster than inflation: https://www.in2013dollars.com/Energy/price-inflation , so consider Insulating for future prices, not just the current price. Yours, Larry

Hi Larry, I appreciate the creative approach here, I need that.
I have not done a blower door test but I would be interested too. The home seems very well insulated and sealed by all indication.
current temps are about 60 at night and 85 during the day and without any conditioning the basement is about 62, main floor 68, and loft 71. I’ve never seen them go higher than that.
Of course heating is the real need in my area but I don’t have any unconditioned data points on that, only that I had one small space heater in the basement and one on the main floor and they kept the house at 50 through a very cold winter here. 

Do you think I should try to find someone to establish manual j and blower door test as my next step, regardless of what direction I go from there? 

tim smith

you ever thought about topping slab over existing with radiant heating & cooling with air to water heat pump. Depending on your locations temp and dew point it might be a good solution. If in northeast or south east not so much although.

tim smith

High velocities can work I guess, would definitely save head room and over all lowered framed in spaces. Not my favorite but sometimes you have to go out of the box to get most elegant solution that will work.

tim smith

what are your design temps in your location? That also will rule out some systems.

clammy

Even though you may think the duct work is too large at the proper static of .75 and .50 you will end up w large ducts . This is done to keep the proper velocity which in turn will give you a quite system . Small duct exceed both static and velocity and usually will deliver less then desired air flow . As stated before head room in basements is difficult at best when dealing w limited head room and duct work especially when the basement is planned to become living space.
Unico systems would enable you to use smaller supply duct usually when I install I use a perimeter loop and never have issues . As other have stated combined w either a heat pump and possible a small direct vent boiler would be a option but they do come w a decent price tag usually not for the feint of wallet or anyone on a budget .
Having ac is not a building required but having heat is personally I would never put all my eggs into mini splits being they are listed as a appliances and when using for heat as the temp goes down so does the cop so heat lose Calc are important and please remember if the grid goes down your done unless you have a decent generator while w a simple hot water system not much power is required for operation as in comparison to any air based system .
I looked into the reisca system that you posted about and I personally can’t believe anyone would install w zero insulation and using cheap canvas flex looks like a big money saver at some one else expense especially using duct board plenums . Looks like it takes just about any required skill out of installing meaning just about anyone can install and get some one w a brain to charge the system .
Try to really remember that when it’s done your stuck w it so spend your dollars wisely and try not to accept a half baked system .
Peace and good luck clammy

bryantroll

tim smith said:

you ever thought about topping slab over existing with radiant heating & cooling with air to water heat pump. Depending on your locations temp and dew point it might be a good solution. If in northeast or south east not so much although.

I had considered doing underfloor staple up radiant heating under the main floor but this would be a heating solution only, and I would have to do radiators in the basement. I didn't believe that pouring another layer of concrete to put radiant into was a good way to go, but I don't know. Can you also cool a house with radiant in the same way?

I am located in Evergreen, CO, at an elevation of 7700 ft above sea level. The average winter temps are about 30-35 F during the day and 15-20 F at night. We do get some cold snaps where temps dip to a low of 0 F, and we did have a couple times last winter where the lows hit -15 F but just for a couple days at a time.

The house seems to hold temp well -- with an average outside temp of about 85 F during the day and about 60 F at night lately the house temps have been: 62 in the basement, 68 on the main floor, and 71-72 in the loft. This is with all windows closed and no conditioning.

What are considerations / drawbacks to high velocity? I feel like I keep hitting dead ends with which way to go, really hoping to find a path forward with one system or another soon.

bryantroll

@clammy thanks again for your input.
My number one priority right now is to identify a HVAC solution and starting moving forward with it -- all of my other rehab plans depend on this -- design and permitting, framing, electrical, and plumbing.

I'm even considering going full circle and considering a boiler system with radiant -- staple up under the floors of the main level and radiators in the basement (or in the ceiling). Perhaps this combined with a single mini split in the main area of the main floor (and optionally in the upstairs bedroom). Cooling requirements are fairly low overall so wondering if a couple strategically placed cooling units would be enough to drop inside temps 3-5 degrees when needed during the day.

I really wish I could make a ducted system work as it just seems to cover more bases more completely -- still wishing I could come up with a solution there. Even aside from my personal wishes to maintain basement headroom, code requires at least 7' of ceiling height and 6'6" under ducting -- and I don't know if I can maintain that without sticking with a low profile ducting solution.

Do you have experience / thoughts on high velocity or any other system that could take advantage of smaller duct sizing?

Trying to stay creative and think outside of the box if I need to in order to come up with a solution.

edit: with that -- I am feeling a bit backed into going with whole house multizone ductless mini splits but am not sure how well they'd handle 0 F degree overnight temps when we get them (and even a handful of -10 or -15F days that seem to pop up every few years), and also if I could achieve decent comfort through the house with them. I do have a single natural gas fireplace in the house and could do some electric baseboards as backup if needed. There's obviously no easy obvious perfect solution though so I have to consider them among all other options.

Hot_water_fan

I think you should do a heat loss. You will not know how big or small these ducts will be until you find out how many btus you need. Then, you can try to optimize their size by determining which spaces can fit into the central system vs. smaller systems. 

bryantroll

I didn’t think to add this until now but this is from the original building plans in 1982. Note the “insulation” details at the bottom of the Specifications section. Also see the Energy Conservation Criteria.
Is this helpful info? Can someone decipher the math provided? 15,000 BTU/h seems low but then again domes are energy efficient. Thinks it’s plausible? 

bryantroll

Hey all, appreciate the time you've taken to respond -- I wanted to ask what you thought of this 'hybrid model' which might best solve my situation.

For a non-ducted solution that provides plenty of heat and at least a little AC, what if I put individual mini splits in the main area of the basement, the main area of the main floor, and one in the loft bedroom which runs warmer than the rest of the house. I will have a ceiling fan in the main area of the main floor/loft, and I could utilize transfer fans/vents to help circulate air into the bedrooms (are these an effective solution?).
Then I could also either have electric or radiator heat in the bedrooms as well to supplement the heating needs and make sure they can stay at a comfortable temp. I am hoping the loads on these would be minimal.

Then I would also be able to push some AC into the house as well via the mini splits just to take the edge off in the summer. Not much is needed but a little would be nice.

Love this idea or hate it?
If its viable, would you expect the supplemental bedroom heating loads to stay pretty minimal and that the main area mini splits would do most of the heavy lifting?
With regards to the question above, thoughts on cheaper to install but more expensive to run electric heating in the bedrooms vs a boiler based system? I could buy a used boiler and will be doing electrical and plumbing myself. Not sure what bedroom radiator solution would be best for either electric or boiler though.

I hope to own the home for 20+ years so I am trying to consider my initial costs vs my long term costs.

Thanks!
Bryan