It's hard to say whether 3 ton is adequate simply by looking at the floor plan, but I like the fact that the contractor is not quick to oversize as many are. Oversized systems do not provide the comfort or efficiency you are looking for. If they did the calculations to determine that 3 tons is adequate, then I would certainly not hesitate to downsize. Many homes have undersized ductwork to begin with, so if you had a 4 ton system to begin with, going with a 3 ton would help allow for more even air distribution. Longer run cycles are better for the equipment and your comfort.

Looks like (3) is also quoting the 2-stage XR16 model, which is essentially equivalent to the newer labeled XR17. Option (2) from your first contractor is for the single stage XR16 model, which replaced the XR15 and again, is essentially equivalent mechanically speaking. The new naming simply better reflects some of the SEER rating capabilities some matchups are able to achieve, but does create some confusion.

I do recommend the 2-stage condenser (previous XR16 model -- confirm with dealer you are getting the 2-stage "A" model and not the newer single stage "B" model -or- XR17), as well as the XV80 furnace for the variable speed blower (which when set up properly assists with airflow on restrictive duct systems and has dehumidification features). You wouldn't be disappointed with this system properly sized and installed. The XR16 (single stage) is also a very nice unit, but 2-stage does give better comfort. You'll have to decide if it's worth it to you. Proper installation of either system you select is the most important thing to consider.

What is the first dealer doing about the existing linesets? Both dealers checked to ensure proper size of existing?

If either has done a true Manual J load calculation, I would not be surprised if the 60k btu XV95 furnace with 3 ton blower was all your home required.

Ryanhughes,

Thank for your reply. Just to clarify, the AC being replaced is a 2 ton system. The contractor is recommending 3 ton. This is for my upstairs floor. The total AC tonnage for the house is 6 tons and it is currently distributed as 4 tons for first floor and 2 tons for the second floor. The contractor is recommending to go 3 tons on the first as well as on the second floor for a total of 6 tons.

For linesets both dealers are going to flush and use the old linesets. They said $200 for new ones,but it is not necessary.

Sorry for my earlier confusion. OK. While I am not there to see your home and spec the system... I do not see your first floor needing 3 tons. With 1100 sqft and an open floor plan as you describe, the 80k furnace sounds even more oversized, for downstairs as well. I suspect your downstairs system is likely oversized as well. An accurate Manual J would determine this. Are all dealers saying 3 tons for upstairs? If so, I'd definitely want the 2-stage model. Also, just to clarify, are you replacing the downstairs system as well?

$200 for a new lineset is a reasonable price and I would go for it, but that is up to you. The new one should be the proper size per the manufacturer specs (or the old one must be). With new copper, you don't have to worry about any contamination from the previous system due to poor installation practices and system condition affecting your new system. But, replacing isn't always feasible, so yes, flushing is often acceptable and enough when done correctly.

This post was edited by ryanhughes on Sat, Jul 13, 13 at 9:31

Ryanhughes,

Thanks again for your response. Both these dealers are saying 3 tons. I have had other dealers who said 3 tons is an overkill and recommended 2.5 tons but they did not do load calculations. I am not planning on changing the downstairs system at the moment, it is working fine.
I am definitely leaning towards 2 stage systems

I would tend to think 2.5 tons myself, if not 2 tons, without doing an accurate load calculation. 2-stage systems do come only in full ton sizes. So a 3 ton 2-stage scroll system will provide about 2.5 tons on low stage. Trane does have the XL20i system that provides 50% capacity on low stage (2 compressors).

Problem with oversized 2-stage systems is you will not see the long runtimes in low, which is the main comfort advantage.

This post was edited by ryanhughes on Sat, Jul 13, 13 at 20:29

What have the dealers said about your ductwork? If system capacity is increased, supply/return ducts must also be enlarged to handle the air volume. Many homes already have undersized duct systems, and installing larger equipment without fixing the ductwork only creates further problems while compounding others.

This post was edited by ryanhughes on Sun, Jul 14, 13 at 13:46