What is the 'sweet spot' now for SEER rating?

[Dargo]

I briefly mentioned in another thread that I need to replace a 3 ton unit with a 4 ton unit. I can't blame the builder. When I built my home, only about 1000 sq. ft. of my 2nd floor was finished. He couldn't put in the size unit I would eventually need. The 2nd floor of my home now is about 2100 sq. ft. and the poor little 3 ton unit generally runs from about 6am until about 4am in the summer months and loses ground if temps get over about 88 degrees outside. I can't possibly insulate more.

That leaves me with the need to put in a proper sized unit. It seems that a 4 ton unit would do the upstairs portion of my main home. Now I need to decide what SEER and what refrigerant I want to use. I'm looking at an American Standard 4 ton 16 SEER using R410. That seems to be the 'sweet spot' between going high efficiency vs cost, but I am not sure of that. Since I plan to live here as long as I'm alive, would I be better off going with perhaps a 18 SEER unit?

I would really like to lower my utility bill. Granted my home and guest house are pretty good sized, but seeing 4 digit utility bills just kill me! Heck, I saw a few companies advertising over 20 SEER systems. I'm just trying to go with what would be most cost effective between the initial cost of the unit vs the savings in energy. Part of me says "go high" since at this time I can get most equipment for about 5% over cost and almost nothing for labor. In 5 years I won't have that luxury. Thoughts? Suggestions? I'm hot.

 

[muleman]

I think proper duct sizing and cfm play as big a role as SEER when you get into a situation like yours. As you go up in tonnage you need to have an airhandler capable of moving enough volume across the coil to be cost effective and avoid freezing up. You might need additional drops in larger rooms and for sure you need a balance of supply and return with a big enough filtering capability. Are your plenum and trunks fiberboard or metal? I run all metal and never use flex unless it is impossible to make steel work. Then it is only for a very short piece.

 

[Dargo]

All insulated metal. Since I knew I'd be finishing additional rooms upstairs, the duct work was all in place to begin with. I just have too small of a system...unless it was on a lower level that had a lot of shade.

 

[muleman]

Do you have an attic ventilator fan? They help a lot in weather like you have been having.

 

[XeVfTEUtaAqJHTqq]

If you dig around there is an old thread when I went through the same issue. There is a web based calculator that tells you what to expect from each unit. I think I went with a 14 seer unit as it was the best option from an ROI perspective.

 

[thcri]

If you dig around there is an old thread when I went through the same issue. There is a web based calculator that tells you what to expect from each unit. I think I went with a 14 seer unit as it was the best option from an ROI perspective.

Sometimes going really high is not always the best. Get your dealer to do a load calculation which includes the different units versus operating cost. Also make sure you qualify for the Federal Rebates unless you have already taken the money. We are selling mostly 16 SEER here but to get the rebate they must also buy a furnace.