We have had a problem with the compressor on our HVAC unit for the past two years. The compressor died in July of 2012, April of 2013 and then again this May. Since it is no longer under warranty, we replaced it.

The company that came out and did the assessment talked with us at length and we were quoted the following system:

Air handler TAM8A0C36V31
Heat pump 4TWX5030B1
Heat strips BAYEAAC10LG1AA
Air Cleaner TFP260A0AH1
XL Comfort Controls TZONE950AC52ZA

The reasoning was to maximize the SEER and EER, allow me to go longer between times going under the house, and be able to control the humidity on days when it was high.

Unfortunately, the company that specified the system was not able to do the actual work, and another company did the installation, purportedly matching the quoted price.

What they installed was a different system:

Air handler TAM7A0B30H21SDC
Heat pump 4TWX5030B1
Heat strips BAYEAAC10LG1AA
Air Cleaner -----
XL Comfort Controls 9374A-XR624

I understand that this is a more standard configuration.

I got a call saying that they did not understand why the first company put the TAM8 unit with the XL15i, because it combines a communicating air handler with a non-communicating heat pump. So when they installed the system, it was the one listed above.

They changed the air handler.
They did not install the air cleaner, because it was specified as a 1" filter and wasn't worth installing according to them (though they did not bother to offer a 5" filter option).
And, of course, the thermostat is not the same, because of the changed air handler.

They are being a bit closed-mouthed about the value of the two systems, and we are going to sit down and discuss things in the near future. My problem is that I have no hard information on my side.

While the more expensive of the two is apparently the more controversial, that is the unit originally 'sold' to us on the basis of benefits and features, and was an upgrade in cost and features from the other, which had originally been discussed.

So:

1 How can I get costs for the different systems?

2 Is it really a problem using the communicating air handler with the non-communicating heat pump?

3 Is a 1" air cleaner less expensive than a 5" air cleaner, and if so by how much?

4 How much difference is there in the cost of the two thermostats?

5 Does both companies being NATE certified mean anything?

6 I know that installation costs are built in to the quote, but why is it so hard to find information on unit costs?

7 Is there any way to communicate with Trane corporate, or is everything required to go through dealers?

The system as installed cools the air, but I could have had a system that does that for under $6000. We paid $7600, after some price adjustments, but the quoted price was $8400, and we will end up paying more than that in the end.