I was in Riverside today to meet with a homeowner that wanted to have his ductwork replaced. He told me that he had his system replaced 10 years ago but did not have the money at the time to change out the ductwork. They bought the best Carrier equipment that was available at the time, but left the existing ductwork in place.
His wife complained that the remodeled kitchen was always hot and the adjoining dining room was unbearable during the summer.
I jumped up into the attic to take a look at what we would be doing and found a couple of glaring problems.

Problem immediately identified. This duct fed the kitchen and dining room.

Here was another, not-so-obvious, problem. This is a high end air filter device. If you look closely, you will see that someone had sealed it with mastic, making it impossible to open and thus impossible to change the filter.
There were some other glaring problems but the pictures that I took on my phone did not come out very well.
Here’s my two-cents on this.
You have four parts to your air conditioner. You have the furnace/ blower, the indoor air coil, the outdoor condenser, and the air distribution portion ( ductwork). The most important component of your system is the air distribution portion. It is the piece that most affects your comfort and the efficiency of your system. You can install the best equipment, as this couple did, and attach it to sub-par ducting and you will waste a lot of your hard earned money. This homeowner has efficiently cooled his attic for who knows how long. He would have been better served to purchase lower end equipment and attach it to a high end duct system. After all, delivered air flow is what you feel in your house. Poor duct design, installation and performance, delivers air poorly to your home. It also kills the efficiency of your new system and destroys the longevity of your equipment. We, frequently, see new equipment installed in new tract homes that fails within the first few years of service because of poor duct design and installation. Do not skimp here. It is a much better idea to install a 14 SEER system on a great duct system than a 19 SEER system on poor ductwork ( and most of the inventory of ductwork in Southern California falls into that category).
I will write a blog post in the future about how we engineer our duct system for maximum delivery. But please, if you must skimp, don’t skimp on ductwork.