Your indoor humidity problems could be a result of an oversized system. 5 tons is a lot for 2400 sq. ft., but your climate might just warrant that.
I'm thinking the same thing Ryan. Temperatures in May-Aug/Sep run in the 90's and avg humidity is 87% at night and 61% in the daytime. The unit didn't seem to cycle on all that much really, but my power bill is still pretty high in the summer months. kwh is only $7.262, but my power bill has seen > $400 for jun-july
One reason I think he is saying 5-ton is it is an older home built in '75. It has good insulation in the attic and below the floors, but the windows are single pane aluminum channel windows, I know I have to be losing a lot of cool air from them... but a couple of grand cheaper a/c would buy a lot of windows... Argh!... decisions, decisions...
I'm gonna go back to renting... it was much simpler when I was younger and renting an apartment and didn't have to worry with this stuff
I'm going to get some more estimates tomorrow , maybe that will help my decision.
The old unit when I moved into here was rated at 4.7 tons but it was in the crawlspace with a duct running into the attic for distribution. That unit was replaced with a 5-ton unit in a closet.
If I were you I would think about upgrading windows, sealing doors and other holes like ceiling boxes in your upstairs ceiling, adding insulation in the attic, and any other areas before having a heat load calc done to see what your sizing requirements are for new equipment will be. paying for new windows and insulation will be alot cheaper and greater payback than a new system without is going to be alot more beneifical to you in the long run and will yeild you a better ROI on the new equipment once you go ahead with the purchase. There's alot you as a HO can do to to increase your over all bottom line on the items I suggested, and even more so if your a alittle bit of a DIY'er where you could do most of that work yourself, as liek insulation and maybe the windows, and definately doing the sealing of door's and other penertration thru out the home.
I am a homeowner in a hot-humid climate too. I have a 2-stage AC but it is strictly a luxury, when money is a sizable concern you will get better use of your dollars by buying a 1-stage unit. They are available up to 15-16 SEER, although the 5-ton size usually drops a point or two in efficiency.
However... infiltration of outside air is a big enemy in climates like yours and mine. It will add serious humidity load to your AC and generally just run up your bills. Back in 1975 almost nobody built tight houses so I would assume there are many opportunities for improvement. The good news is sealing up air gaps is cheap to do. The bad news is it is labor intensive and very difficult to find people to do it for you. There exist some sophisticated methods for measuring your house tightness but they may not be widely available in your area. When you get tight enough, there is a need to pay attention to explicit ventilation systems, but that is probably academic when you start with a 1975 house.
For the subject of windows (also mucho expensive), let me observe that so much of the time the temperature difference between indoors and outdoors is 10-15F or so. That is the basis for some saying double pane is not so important. The real reason for double pane windows in the South these days is the anti-heat-ray coating is fragile and needs to reside on the *inner* surface of a double pane where it cannot be scratched off. I suggest you look into solar screens as a cost effective thing to do first.
Sales people always say "more insulation". Well insulation is usually good but if it is applied over a leaky ceiling with many cannister lights, I think it is the wrong answer to the problem. If you don't have radiant barrier in a ventilated attic, you should get some unless your house is nearly always shaded. Radiant barrier can reliably save 8-12% of your AC usage in our climate, it will make your attic cooler in a way you can really feel.
A high efficiency AC will save *some* money, but the way to make sure your house is not an energy hog is to get better sealing. I would not feel ashamed of 13 SEER but the money saved should go into making your house tighter, if you can.
Or heck use HVAC Calc and do the figuring yourself....then you can instantly see what upgrading insulation or windows may do for you. With that info you might be able to choose the best option where you get a more efficient system and were also able to choose the best envelope upgrades to compliment that for your money.
Thanks so much guys... I have learned a ton in the last two days by pouring over the archives. I never knew how important some things were that my house is lacking.
I know there are some areas in the ceiling lights that are not sealed properly. I didn't know how important this was before. I've replaced 7-8 recessed fixtures already and will replace them all now. I know that anytime in the past when I've had a fixture removed, I could feel a lot of hot air coming out of the hole into the living space. So.. I'm going to get to work on fixing those items. I also need a vapor barrier in the crawl space.. that can't be helping Also think I want to install a radiant barrier on the joists to try and keep the attic a little cooler. The Duct-work is in the attic, so that might help. I think I could stand to save a good bit of money with some diy grunt work to make my house tighter.
I think I've pretty much decided on the Bryant System, just not sure on which one yet.
It's either a 13 seer Bryant heat-pump unit
or the 16-seer Bryant Evolution (W/ 2stage compressor & Var Spd Fan) heat pump system for 2grand more (after rebate).