How many days each year do you use Air Conditioning? Also, specifically where do you live in LA area? (Town/Zip?)

House is in Culver City, 90230. I haven't moved in yet so not sure how often we will use the AC. I would estimate for a few hours per day? We are from the East Coast so probably won't use the heat that much.

If you can split living/sleeping spaces do it. Especially with new thermostats. It allows you to read the temps in your bedroom vs a vaulted ceiling living room. Of course there is a savings and it also just down on noise and uneven cooling.

Ecobee is a great thermostat that allows you to run multiple temp sensors. It also allows you to run sensors onto your sliding doors or windows so you can have AC only come on when closed.

There is a lot more to HVAC then there used to be. Non central return to cut down on that excessive noise is just one. There are also ways to split a single system by using switched ducting.

When we moved from the East Coast the thing that shocked me the most was the temp swing in a single day. Temps can easily be in the 90's during the day and the 70's and night. Using a system that can use a fan to draw cool air in at night is a plus.

I have had two split systems and NEVER AGAIN!! Especially if you split between two floors. One had 3 compressors and one has two compressors and we have redone this system twice! I am in Texas and we USE our AC a lot, like most of the year so could be different, but do be careful.

what do you mean by split zone? You mean 2 zones, one zone for upper and another for lower? (when i google split zone, i get multi split system... probably not what you mean). I would recommend separate zones so that you can cool the rooms when you sleep without cooling the rooms you don't need. That'll be a waste of money and resources. I have 3 floors in my house and have 3 zones, and I have nest thermostats.

Are compressors more quiet? curious....

What fuel will you use for heating?...your post is confusing....if you want best control and comfort, then you have multiple choices. Either a separate system for each zone up and down or one system with zoning controls. If one system, I would go with either a two stage condenser or a var speed condenser which would be best.

IMO

PDK830,

Zoning is a good option for your floor plan. Realize the idea behind zoning is more or less : better control of system = better comfort.

2 story with 1 HVAC system and 1 thermostat means less control and temp swings from various areas can be upwards of 15 degrees difference from that of where your current thermostat reads. ( depending on heat loads and other factors)

If you merely put in a 2 zone system it will be better than single zone, but there is still likely to be areas that are warmer than others. If each bedroom has it's own zone, better control for temp in those areas... same thing with other areas of the home.

a 2 zone should not be referred to as split zone. I am only guessing this is what the contractor may have said but 'split' system is often referred to as a normal HVAC ducted split system and not one with zoning attached to it. So adding 'split' to this specification kind of clouds things.

If what I've stated above is incorrect, repost and list how many zones your HVAC contractor specified.

As already stated if you choose the zoning option it is best to pair this type of system with multi stage AC equipment. The more stages the AC has the better it will perform with a zoned HVAC system.

Thank you for the comments and apologies for the confusion. I am probably not using the terminology "split zone" and "2 zone" correctly. I will be moving the furnace and coil from a first floor HVAC closet to the attic and the condenser from the ground to the roof. I was also told I need all new ducting (current ducting and HVAC are from mid-1980s). I have received two very different quotes for equipment. Please see below.

Quote 1: 4 ton 18 Seer Horizontal Split System, Furnace Model: 58CVX090116 – 80% (2 Stage Heating – Variable Speed), Horizontal Coil Model: C48H175P156, Condenser Model: 25VNA949A003 – (5 Stage Cooling – Variable Speed). Carrier 2 Zone Infinity System- Zone 1 for first floor, Zone 2 for second floor. Infinity user interface and smart sensors

Quote 2: Bryant 4 ton 14 SEER Horizontal Split system. Install Bryant 4 ton 80% Single Stage furnace model# 310JAV048090. Install Bryant 4 ton 14 SEER R410A coil model#PL48H210P75635. Install Bryant 4 ton 14 SEER R410A condenser model# 105ANA048000.

Quote 1 is significantly more expensive but has far better equipment than Quote 2 and has 2 zones. I have asked Contractor 2 to quote me a more efficient condenser (because it will be on the roof and I want it to be quiet) and a 2 zone system. He is in the process of doing so but said for the size of my home, it will take many years of electricity cost savings to break even on the additional cost of installing a 2 zone system. One other thing to note is that there are 2 bedrooms on the first floor and one of my children will be sleeping on the first floor so we will likely need to cool both floors at night anyway.

Hope this helps clear up any confusion!

Have you explored ductless mini split aircon? (or heat pump if you need heat in winter as well)? This way you can control each individual rooms. where are you located and what are your heating and cooling needs during the day and night?

rawegg- I have not looked into ductless mini split systems but perhaps I should. House is in Culver City, CA (Los Angeles), approximately 4 miles from the ocean so there is a nice ocean breeze. I frankly don't know what our heating and cooling needs will be because we haven't moved in yet.

"for the size of my home, it will take many years of electricity cost savings to break even on the additional cost of installing a 2 zone system."

Like multi-stage, multi-zone is not about savings, its about comfort.

My multi-stage cooling is indeed all about savings.

I actually have to wonder if the OP even needs A/C in Culver City - and he says he hasn't moved in yet but never answered my question about whether the existing home even has A/C.

SaltiDawg- the home has a 30+ year old furnace, duct work and AC condenser. The AC has not worked "for a couple of years" according to the seller. They got by using ceiling fans and leaving the windows open. We are originally from the East Coast so we like it nice and cool!