clockwork you will always get more comfort and control from multiple systems over a single system with zoning controls. however, a zoned system like you have listed is certainly a viable second choice and not overkill. dealer must do his load calcs for equipment and Man D for ductwork sizing/design. Ductwork should be insulated probably R8. I would want metal trunk lines for both supply and return. what did dealer propose? I think your biggest challenge is verifying your dealer's experience/expertise with a sgl system using zoning controls. I recommend going to visit a newly constructed home similar to yours where zoning controls were used and discuss with homeowner. Zoning is not for the inexperienced. how much is this system? IMO Good Luck!

2ea 5 ton 16 SEER Systems in the Goodman Brand with duct systems in Tulsa from www.morrisheatandair.com would have cost no more than $30,000 for equivalent products. Check out these brochures and find a Goodman Installer today on Angieslist. New 98% AFUE Furnace with true variable speed motor. http://www.goodmanmfg.com/DesktopModules/GoodmanProducts/ProductFiles/32CB-GMVM97.pdf New Evaporator with TXV http://www.goodmanmfg.com/Portals/0/pdf/CBs/CB-GEVC.pdf New 18 SEER AC http://www.goodmanmfg.com/Portals/0/pdf/CBs/CB-DSXC18.pdf New Comfortnet Communicating Thermostat http://www.goodmanmfg.com/Portals/0/pdf/CBs/CB-CTK03.pdf Goodman Brand Air Cleaner http://www.goodmanmfg.com/Portals/0/pdf/CBs/CB-GIAQ.pdf Even if you are not in a Goodman Area, Daikin should be available in the same specs for that much, I would consider a Ductless Multi Split System with 12 indoor heads and up to 12 tons of cooling capacity, however they are not gas driven furnaces they are heatpumps. 3ea Daikin 4head systems would cost no more than $45,000. They operate at 19 SEER and usually qualify for a bunch of rebates. Here is the brochure: http://www.daikinac.com/content/assets/DOC/Product%20Brochures/CB-MXS.pdf Daikin and Goodman are the largest Manufacturers in the United States. Good Luck John Morris (918) 734-0040 www.morrisheatandair.com

ABOUT DAIKIN https://www.ductless-mini-split-air-conditioner.org/ Daikin stays at the forefront of ultra-efficient inverter technology as well as creating safer refrigerants to keep up with the global demand to reduce CO2 emissions. They are the inventor of the variable refrigerant volume system (VRV) and an innovator in the split system air conditioning market.Daikin has also co-developed R-410A refrigerant with Carrier. They are the only manufacturer to produce their own refrigerant and compressors. Daikin is committed to meeting the challenges of global warming and a need for sustainable resource use by bringing you more efficient technology with minimal environmental impact. For more than 80 years Daikin has been producing innovative and energy efficient climate control products tailored to fit your needs. They have become a total solutions provider though unique product lines to fit your requirements and budget. Daikin is known for it’s world class innovation and reliability. They have received the iF Product Design Award and the Google Design Award in 2010, the Plus X Award for innovation and the Red Dot Award in 2013, and the Universal Design Award in 2014. Their heat pumps are designed to extract energy from ambient air as to reduce electricity consumption. They combine this with inverter control, VRV and heat recovery. Daikin aims to create the most efficient climate control solutions for residential, commercial, and industrial use.

I'm disappointed that what had at first seemed a very balanced comment was followed by what seems to be misinformation and misdirection. People buy ground source heat pump equipment because they want to and can afford it. Or decide they need to in their locations. They're hugely more expensive than alternatives, which is why they're still not very common. "When’s the payback on a Tesla? People still choose to buy them for reasons other than the ‘bottom line’." Not a comparable. A false analogy. "I would not choose natural gas or propane for reasons relating to the environment, safety, IAQ & paying for yet another utility hookup for an energy source that might not even be used for months on end during the year." What effect having a gas furnace has on indoor air quality. Another hookup? Most people prefer gas cooking appliances and besides, the OP is talking about an existing home, he either has gas service or he doesn't. "Rather than spending perhaps tens of thousands of dollars on a Solar Array, I would sooner invest that same money, hopefully less, in a ground loop for a Geothermal system." Sure you would, that's the business you're in. The ground source heat pump market is not growing as expected by those in the industry, which suggests that your opinion isn't widely held or easily sellable. In many parts of the country, solar panels can have a quick payback. Not so ground source heat pumps. "I often hear about Solar Panels when geothermal is mentioned, as an alternative way to save money by creating energy." In a place like Texas, where electricity is cheap (other than during cold weather crises as they just experienced) there's likely no payback from a solar panel installation. People do it as a personal statement, call it for environmental or other personal reasons. Like buying the Tesla, not a financial decision. An HVAC system blows warm air when it's cold, cool air when it's hot. It's one of those things people don't care about - either it works or it doesn't work. Spending extra money for an exotic system doesn't equate to extra payback when the home is sold. Neither owners, nor visitors, nor people passing by, nor anyone else, concern themselves with what's doing the work. It's equipment that doesn't produce an experience for someone in the house if it's working. In the US, there are vast areas where electricity is cheap. It will remain so for some time. People don't spend money today to potentially save money 10 years out when market conditions may or may be different. I suspect you could build a house with mahogany or teak framing. Or you could paint the framing bright colors. Why bother, you can spend less money and effort and get something else that will do the same job. "We almost never use setbacks at our home - even when going on vacation for weeks on end with no one home, our geothermal just runs." You're combining two different things to produce confusion. Thermostats that have a setback feature ALL are set up to provide lower overnight temperatures to have more comfortable sleeping conditions and then a recovery in the morning before wakeup time. As sleep specialists recommend. That in demand comfort features isn't possible with ground source heat pumps because the warm up period from a setback is too slow to be convenient to use, absent triggering a secondary heating source (like a furnace) to help. THAT'S why you don't "believe" in setbacks with a heat pump - they don't work. Turning down a thermostat during heating season when the home will be unoccupied is not a "setback" as that word is most commonly used. It's done to save money, why heat a vacant house? No setback thermostat is needed, even a dumb 50 year old analog thermostat can be turned down.