You need to have a heat calc done; either by your contractor, or yourself (HVAC-Calc). Depending on what your loads (sensible and latent)are, a 2.5 ton unit might be the right one for you. Your lack-luster performance by your current system may be due to the fact that it's mis-matched.

Bear in mind, that 2 stage units are available in whole ton sizes, only, and even running in first stage, many do not remove humidity as well as a single stage unit. So, you don't want to oversize.

As far as the stat, you want one that has dehumidify on demand and not simply one that 'over cools' to dehumidify. A PRO will be along to comment.

V

They are going up 50% in capacity. Are they enlarging the duct system by 50% to handle the extra air?

Thanks, I decided on the 3 Ton. Even if the 3 Ton is slightly too big I will have the Honeywell IAQ hooked up to control humidity and Cycles Per Hour. Therefore, I can not foresee any problems.

ac rookie

listen to Baldie

going up in size by 50% is a mistake without ductwork modifications.

why not have dealer perform the load calc so you will know for certain?

has dealer even bothered to check ductwork? a good dealer would have already made an evaluation and reported back to you.

two ton system needs ductwork to move about 900 CFMs both supply and return. three ton needs about 1300 CFMs both supply and return.

IMO

I'm in Howard County, but used a contractor from AA. (Installation will be finished tomorrow) I would get more estimates and make sure they do the load calcs. It's not always about lowest price. Tell them about any comfort issues you had in the past when the system did work. Have them look at your ducting (if they won't do that than move on to the next since there are plenty of contractors in the area). I believe you get what you pay for and you want to pay for a good installation, otherwise you will be paying again sooner than you would expect.

The tech did look at the duct system or rather the main trunk, he said it was big enough. Do you know what size is adequate? I would like to check it myself if possible.

Thanks

ac rookie...I just went thru the same thing. My home is the same age and smaller than yours and I went with a 3 ton Bryant Evolution 289B. Even on these marginal days it does a great job of removing the humidity. I have been able to get the humidity down in the low 50's by setting the Evolution controller at 50%. If I set it lower it would bring it under 50%. The system has only run in low stage which is fine with me. The issue that remains to be seen is how it will perform in the 2nd stage. I really do not have alot of concerns because I don't think there will be many days that will require 2nd stage cooling. I am happy to keep it running below 5 amps. without seeing your ducts it would be impossible to say whether they are adequate or not but I would bet thery are not. I had my ducting replaced and am I glad I did. The 26 year old supply trunk insulation was deteriating and was very dirty from leaks in the system. Now is the time to get it right. If you are going to get the ducting done do it soon before it gets unbearably hot and your installer charges more. Good luck.

Your home is very similar to mine (although I have a larger finished basement area. I had a 2.5T system, but the ducting was so poor to the upstairs (return and supply) that I ended up having to get 2 systems installed (alternatives were to be uncomfortable with a replacement system or to rip apart the house to redo ducting). My load calc came in right in between 3 and 3.5 tons (thanks to a lot of high ceilings and the addition of skylights) but I have 2 - 2 ton 2-stage Infinity systems. My installer determined that in low stage I would be just fine for sizing. He did point out that the old setup would have been at the limits of a 3 Ton system. The only downside is in order to get all the new ducting and add gas (per the wife's demand) I had to spend a good bit more. Of course, we plan on being here for many years so the investment in comfort is well worth it IMHO.

You should really get multiple quotes from a few contractors. Some are better than others and discuss any issues you may have with the current set up. Let them give you different solutions and then armed with expanded knowledge and options make the decision that best fits you.