2200 square foot designer with a 300 square foot enclosed lanai. (Total 2500 square feet. We do have a mini split on the lanai but rarely run it anymore. We leave sliders to the house open.) Cost after tax credit in the 14K range.

Be aware there are different tiers of HVAC companies. There is Premier, Mid-tier and builder grade. Premier is the best quality and the most expensive and Mid-tier in-between and builder grade the cheapest and worst quality. All will work well but the Premier systems statistically will last the longest with the least amount of problems. So, there will be differences in cost depending on the brand you choose and you usually get what you pay for.

2Stage air conditioner
 

We put one in in March. Love it! Temperature is so consistent, had it set on 75 in April perfect night and day. Quieter both my husband and I noticed how much nicer the temperature was in the house. Not sure about cost savings as we installed a heat pump for our pool the month before. We left for the North in May. Nice to have the thermostat on my phone to check the house temp. It is worth the upgrade.

I made an error in quoting the cost after subtracting the tax credit. The price was 12K.

We changed out our central ac a few years ago to an Airtemp unit that has a scroll compressor. They are very efficient. The old unit was a Trane with a rotary compressor. Our electric bill is half of what it was and the unit cools better. This is without the complications of a multi stage or variable system. The ac expert told me that the super high efficiency systems rarely achieve the rated seer and they are much more susceptible to break downs

Installed a Bosch 4ton variable unit last year. Installed a variable speed pool pump at the same time. Savings have averaged about $100 per month on Duke bill.

It kind of is a gimmick.
1000 watts of power is 3412 btu’s of heat transfer. I pay 11.2 cents per 1000 watts with Seco. Here is no way you will ever get your money back unless the unit lasts 25 years.
Electricity is SO cheap with Seco!

Yes we have a Bosch also ! BEST PURCHASE EVER

Comfort is the reason to go variable speed.

Poster #21 says otherwise.

I really don't understand the hot and cold room situation. My thermostat never deviates more than one degree from the setting. It sounds like a thermostat issue, or maybe an insulation issue. A variable speed compressor still uses a thermostat to control when it comes on or off.

As you are aware, single stage units are like a light switch, either full On or full Off. A variable speed inverter system can be full On and full Off and 80 steps in between. I don't understand this 100% but what they are claiming is since the variable speed runs longer and slower once the house is at the set temperature, this gives all the rooms in the home enough time for the temperature to equalize better. That's the principal and I know from people who have these systems that this is indeed the case and a more comfortable house. You also get the benefit of better air filtration because of the longer slower run times.

As far as zoning, in my home in NY where we had a basement and two levels it made a lot of sense to have multiple zones but here in the Villages since all the homes are single level and not that big except for the premier homes, I don't think you save much only cooling the bedroom and not the rest of the home for example, since at night the AC load is minimal And in the winter you want the whole house to be at a certain temperature when it gets close to freezing since the extremeties of your home will be colder than the core. Just my opinion on that topic.

Once I get my variable speed system I'll report back on the pro's and con's that I see.

People should understand that only about 5 percent of new units being sold today are variable speed, they are very expensive, more difficult to repair, and you will never recover the cost. If a variable speed unit would make my house more comfortable, I might buy one, but I don't think it would. Personally, I think that many people who buy these expensive units do so because a salesperson exaggerates the benefits. Do your own research.

Can you explain why a heat pump needs 80 different steps of cooling to keep a house at the proper temperature? Why would it use step 20 at one time and then change to step 60 for another time? Whatever of those 80 steps is being used, it will be the same for all rooms in the house, if you only have one zone. As I have said, my house temperature never deviates more than one degree from the thermostat setting in any room at any time.

As I am sure you know, a heat pump runs most efficiently when it is running continuously. So a system would use step 20 on a cooler day and 60 on a warmer one. In both cases running the unit continuously.

It is amazing that your whole home never deviates more than 1 degree (F) from the thermostat set temperature. That is such a tiny number. You have only one thermostat so you must keep a thermometer in every room in order to know that. and you must really fine tune the dampers as the heat load differs from room to room. But I am just speculating. Regardless, congrats on having an incredible home. In my house the temperature in the corners of the house differs by more then 1 deg F from the temperature at the thermostat.