You are certain 2 ton is correct size? I prefer AmStd over Carrier. I am going to suggest another configuration over the systems you listed.

9033591 Active Systems AMERICAN STANDARD SILVER 15 AMERICAN STANDARD 4A6H5030H1 *AM7A0A24H21 805 27200 12.50 15.25 26400 9.00 17300 1 HRCU-A-CB 216 538 Yes

Probably a 7.5 KW heat strip. Trane 824 thermostat or HW WiFi equivalent.

IMO

Thank you very much! Many units with my floorpan use 1.5 tons, but my unit, and a few others, are "end units" with several more window than similar interior units, assuming you are thinking too large. I will discuss your recommendations with contractors. I follow your comments on other threads and especially wanted to know your thoughts regarding American Standard vs Carrier. (A few contractors mentioned that Carrier is not as good as once was since no longer made in US, but that may have been more about selling Am. Standard.)

Yes, sometimes the best way is to really find a professional that is mostly reliable and clean. So many so called professionals in Florida at least are not. You end up paying more in the long run. I did hire however hvac services from a company called Coral Springs HVAC Services. They at least provide many other services like AC repair in the hot weather here.

another system recommendation...no, I was thinking 2 ton may be too small for 3 story TH in DC area...

5021089 Active Systems AMERICAN STANDARD SILVER 15/GOLD XI AMERICAN STANDARD 4A6H5024G1 *AM7A0B30H21 835 24000 12.50 15.00 22600 9.00 13400 1 HRCU-A-CB Yes 202 507 Yes

IMO

There is a about a 6% difference in operating costs between a 14 and 15 SEER system. The minimum SEER in the southern states which includes Virginia is 14 SEER. All builder's grade equipment must be at least 14 SEER. When you move up to 15+ SEER you are getting better equipment with more features in addition to better efficiency.

Is each floor 500 sq. feet? If the air handler is in the attic, does the duct work come down to the second and first floors through the walls? In what direction does the end wall face? How many windows face the south and west?

It would seem a 2 ton unit would be marginal, but if that size worked well in the past then you should be good. Make sure you really have a 2 ton condenser.

It should be noted that the first system I gave you was a small 2 1/2 ton system, extra BTUs on both cooling and heating. Second system was a 2 ton with full cooling BTUs. If you have an existing 2 ton and it is satisfying you on comfort, then the second system I provided should be just fine. You have an option though. Any idea of your lineset size you have now?

IMO

Hello tigerdunes. I do not know the lineset size. FYI, the first floor is a basement and the temperature is consistent throughout the year.

Hello Mike. Thank you for your input. Each floor is approximately 500 sq. ft. The first floor is a basement which has consistent comfortable temperature all year round. The air handler is in the attic; currently installed upright. The new handler will be installed horizontally. The existing duct work comes down through the walls to all floors. The exceptions are overhead vents in the master bedroom and the bathroom, both of which are below the attic. The vent in the second bedroom below attic is through the wall. The duct work in the attic will be reconfigured to accommodate the horizontal air handler.

It is an end unit townhouse. The front of the house (one window, one door on ground level and one window on upper level) faces NW. The back of the house (one window, full view glass door with inset blinds and small kitchen window on ground level and window and small bathroom window on upper floor) faces SE. The one long "outside" wall has two windows each on ground and upper floors and faces NNE. The other long wall is a common wall with adjoining townhouse. As an FYI, the complex was built in 1940s to house officers during the war. Refurbished in 1974. The exterior walls are concrete block and brick. There is no insulation on exterior walls. There is insulation on attic floor and soon to be on attic ceiling and in basement.

I currently have a Trane XE 1000 2 ton that was installed in 1992 after the then Trane was struck by lightening. Probably a 10 SEER, at best. I have had zero problems with it.

I agree a 2 ton size should be OK. Basements at or partially below grade carry very small heating loads and usually next to nothing on cooling loads. However a dedicated dehumidifier might be necessary.

IMO

The 2 ton size makes more sense now that we understand 500 sq. feet is a below ground basement.

Are planning to finish the attic? If so are you planning to heat and cool it?

First off, you don't need a 15 KW heat strip. What size do you have now? 10 KW more than adequate.

did you get a quote on the system I recommended? See below.

5021089 Active Systems AMERICAN STANDARD SILVER 15/GOLD XI AMERICAN STANDARD 4A6H5024G1 *AM7A0B30H21 835 24000 12.50 15.00 22600 9.00 13400 1 HRCU-A-CB Yes 202 507 Yes

As to the two systems you listed, quote #1 is the best value and it has the superior performance/eff numbers. See below.

7560059 Active Systems AMERICAN STANDARD SILVER 16 AMERICAN STANDARD 4A6H6024H1 TEM6A0B24H21+TDR 800 24200 13.00 16.00 22000 9.00 14100 1 HRCU-A-CB Yes 191 493 Yes

You want Thermostat AS 824 or similar HW model. New lineset included?

IMO

Thank you tigerdunes. No quote back on your recommendations yet, but contractor of quote #1 indicated that Silver 15, 4A6H5024 would be $169.00 less than the $6,949 for Silver 16. (I am assuming same air handler since he did not indicate a different one.)

I assume this is a 2 ton system although you fail to provide model numbers. Pricing on the Trane XL16i system is over the top ridiculous. I suggest you go back to AmStd Silver 15 and 16 model systems, same as Trane's XR15-16 systems.

IMO

attic ducts are not insulated now?...this is not clear...

TD

what did AmStd dealer have to say about this?

TD