Looking to determine best approach to multi zone HVAC and automating it (Texas)

Before anyone recommends it, I have already reviewed the thingsthatarsmart.wiki pages as well as searched here, and I am not finding what I am looking for.

I am wanting to start a discussion to throw around some ideas.

I am remodelling a 2K sq/ft ranch style home in coastal Texas that is all electric so somewhat of an oddity here in the land of petrochemicals…

In this remodelling I am at a point where I MUST replace my aging and now failing HVAC system. We are replacing a 3 ton system with a 3.5 ton system based on cost, avaiability, and reliability.

I am however wanting to do a multi zone arrangement, where I can keep different rooms at different temps. It is just the wife and I as well as our pets, and God willing a kid or two down the road shortly depening on foster / adoption proceedings but I digress. The living room / kitchen / dining room should be kept a few degrees warmer during the cooling months than the bedrooms. And I am looking at how to control, or manage this.

The bedrooms are sized as follows.
Bedroom #1. 12x16 184sq/ft
Bedroom #2. 10x10 100sq/ft
Bedroom #3. 10x12 and 120sq/ft
Master Bedroom 12x20.

The master bedroom is directly attached to the master vanity / dressing room which adds a funny shape, but effectively 10x12 space, and a 6x6 commode / shower room. That gives the master suite a grand total of 396 sq/ft.

The remaining interiior space is kitchen, living, dining, laundry, and hallways. The living room is not a formal living room per se but more like a great room / family room.

I guess the question is how best to approach division of the HVAC, and automate it. So for example, if noone will be in the middle bedroom A.K.A. home office studio, I still want temps under 78 degrees, and RH between 45 and 60% to keep my guitars from getting messed up.

The options I see are…

#1. Add additional small systems for the bedrooms and close off the ducts from the main system.
#2. Add mini split systems for each space we want handled independent of the main system, and again, close off the ducts for the main system.
#3. Add a shutter system to the main system to allow it to send more / less air to each room depending on temp and RH readings.
#4. Add smart vents to each room to control air flow.

I know for the main thermostat, and the master suite thermostat I want to use / keep using my Honeywell 9000 series WiFi smart Thermostats. I currently have the RTH9580WF in the main hall / living room area, I am pretty sure I want to stay with Honeywell as the app works fine and integrates with ST and Alexa great, but I think I want smaller thermostats for the individual bedrooms, OR accurate temp sensors that I can open / close shutters with…

So what are your thoughts. Not just the solutions you might have come up with, but why did you go the way you did? I am looking for advantages / disadvantages of whatever methods are out there.

My end goal is to increase the functional comfort of our home while reducing operational costs.

It should be noted as part of the remodel we are packing lots of insulation throughout the house, and adding a radiant barrier into the attic…

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I’m not deeply knowledgeable on this but here’s my experience, FWIW.

We built in the Texas Hill Country, moved in last summer. So I’ve now got one full year with the new house and its HVAC.

We have a single heat pump system with shutters dividing the house into three zones: master bed/bath, living/kitchen great room, and guest bedrooms. Total of just under 3000 sq ft. Carrier system with three Honeywell 8000 series Wi-Fi thermostats.

We’ve had the HVAC installer out three different times to tweak the air balance.

It all works well (after a replaced main control board) and it has been economical to run.

But I don’t ever get more than a degree or two difference between the zones. With the master set to 71 at night and the other zones at 76 (and master doors closed), I still find the other zones at 72 or 73 in the morning.

Given that the operational cost has been good, I’m trying to learn not to stress over the temps. :hushed:

Assuming that you have basically air leakage throughout the house / between zones which is somewhat expected, I would think that’s okay…

I know the temp differential between rooms that have effectively been shuttered off via decently sealing registers, there is typically a 4 degree temp differential between that room and the rest of the house…

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