Thermidistat - A/C decisions

[patanj]

Hi here is a question(s) that I need answered. I am purchasing a new home in sarasota, fl. approx sq. ft of 2200. If I want to add a thermidistat, the builder is requiring me to also upgrade my A/C unit from a 12.0 to a 12.5 seer, with variable speed. Both units are 5 ton. The cost all together is close to $2000, $ 600 + for the Thermidistat and about $1,200 - 1,300 for the A/C.
Questions: 1- is the thermidistat necessary in Florida? I have had different opinions.
2- is it worth it to upgrade the a/c or can I go and buy a thermidistat and use it on the original single speed unit? can it run on a single speed unit and can it be added later?
3- is the cost actually $600 + (unit and installation)
4- they have a humidistat available, but I have been told that it is of no use in florida. Is that true? It is my understanding that a thermidistat is a "glorified " thermostat and will make the a/c go on and off because of either the air temp or the relative humidity.

Thanks in advance,
Pat

[imeduc]

Boy Id have to see this home ,2200sqft and 5 ton??????? First Id say it will cool the home to fast and shut off and not get the humidity out of the home.A smaller unit that will run a long time will do a better job. Dry it up inside the home and you will feel cooler. SO rework the ac load. Now a 12 seer down here forget it go for a 16 seer for sure.Also ask about a hot water recovery unit to go on the AC . This will help kick up the Seer on the unit and give you free hot water for 6 to 8 months down here. I can turn off my water heater for about 8 months here . With 3 in the home and the water run about 140o have all we need. Now on that tstat deal here if you go away for a time we run the AC of a humidity control set there on the wall next to the tstat and wired in to it. When your home run it just off the tstat. Over there dont know why. They try to sell you a heatpump dont do it .Just the AC and strip heaters is all put the $$ in the bank you wont have the heat on that long. For a pool heater go solar,but not for the home hot water. Why do I say all of this Cause IM over in west palm beach and I have been here a long time and also own a hvac shop. Also have a sisterinlaw over in Venice

Hope it all helps

ED

My mistakes dont define me they inform me.