A well designed house does not necessarily NEED to have all rooms maintained at similar temperature. To get a high SEER on a central system, the duct work must be well sealed and insulated.A properly ducted central system with high SEER and high AFUE is efficient and maintains the entire "envelope", keeping everything at a constant reasonable temp...
A well designed house does not necessarily NEED to have all rooms maintained at similar temperature. To get a high SEER on a central system, the duct work must be well sealed and insulated.
Zoning a central system is difficult/expensive.
This to my mind and experience is the issue. My basic contention is that the unitary manuf can put all the technology they want in the equipment, BUT, between that equipment and the homeowners comfort is a completely inadequate duct system. The equipment manuf are strapped over this issue. Since ‘15, the National Codes require a max duct leakage of 6%. I am not aware of exactly how many states are actually enforcing this code. Even if they are, you have to look at ALL the duct work that has been installed prior to that time. The DOE has said the average residential duct system looses between 18 & 42% of its energy in duct losses. I represented duct sealant manuf for over 15 yrs and that business was almost 100% commercial. Inverter equipment on ducted systems, especially on a retro-fit application will be problematic due, not to the equipment, but to the deficient ducting.
A well designed house does not necessarily NEED to have all rooms maintained at similar temperature. To get a high SEER on a central system, the duct work must be well sealed and insulated.
Zoning a central system is difficult/expensive.
Duct systems that are not duct sealed must be when a new install is done, in fact in my zone there is HERS rater testing required before and after install.
A well designed house...in nirvana I guess you can overcome physics. Not heating a space when you heat others creates a cold sinc, same thing with cooling, just the opposite.
Insulation and proper fenestration slows down heat loss and heat gain from outside, not conditioning a space inside causes infiltration.
Unless you envelope every room and weather seal every door and never open them.
I rarely recommend zoning central systems, because of the room required around the equipment to do so and the initial cost(although that is getting better now). I do argue that the miniscule difference in energy used to condition the entire protected area inside the home verses zoning (except for different levels - where heat gain and loss is dramatically different per level) is well worth it because of infiltration.
The inherent problem with mini splits is that the they are essentially throw away systems, repairs after 7 plus years are expensive and in many cases parts are simply not available.
There's an old saying that applies to high tech..."trick parts have trick prices and trick problems".
Even high SEER central systems are now prone to this, recently replaced a blower and circuit board in a Rheem 95 plus 16 SEER unit just out of warranty, that $400.00 blower replacement (old cost)cost the homeowner over $1,500.00.
YD, After several years I do think you will be surprised at the performance increase if you pull the entire cover off the unit and clean the coil. All the build-up seems to happen on the back 40% of the coil that you cannot see. Also, a good cleaning of the fan blades will yield noticeable results.