Proposal:
One three ton and one 4 ton XL16i:
Condenser: 4TTX6048E, four ton
Evap Coil: TXH54
Furnace: XV80
Thermostat: 803
Parts and Labor: $11,399
Condenser: 4TTX6036E, three ton
Evap Coil: TXH033
Furnace: XV80
Thermostat: 803
Parts and Labor: $10,239
Less $1,500 if I do them at the same time.

Questions:
1. Price reasonable?
2. Many negative comments regarding XL16i on this and other sites. My contractor addressed by saying if system is not installed correctly there will be issues. [They have been in business since 1945, we have been happy with them]. XL15i system would be approximately $1,500 less per system, less efficient. He has 16i in his home. Some of the negative comments are some time ago, are there still issues with this system? Should I be concerned enough to go to the Xl15i?
3. He said our lineset does not need to be changed, just flushed, it is bigger than needs to be and that is OK. Is it?
4. Some on this site recommend Honeywell thermostat. He said they look and operate the same. I understand the Honeywell is a bit cheaper, should I make an issue of this?
5. We think we need to purchase the extended warranty, installer did not push at all, just pointed out pros and cons when we asked about it. Recommended?

My neighbor has issues with this sytem, but they did not change out their 16 year old thermostat nor do I believe they have a variable speed furnace. So I think they are a good example of a poorly installed XL16i. How do I get comfortable with this big ticket expenditure? My installer is A+ BBB, and been in business for 60+ years.....
Thanks in advance for any input you may have. If you need more info please let me know.

have you asked about American Standard?
Am St & Trane are same mfg, more bells
and whistles with trane.

I see no mention of duct sealing.
if you seal the ductwork, supply boxes and return
airs then you get more of the air you are paying to
heat and cool into your house.

on an average we find 30% duct leakage.
but you have to test to know what your amount of
leakage is. otherwise its just a wag.

no mention of loac calculation either..
7 tons is a LOT for 2700sq ft.
even with bad rule of
thumb sizing of 500 sq ft per ton its big.

when units are oversized they short cycle.
meaning they don't run long enough to remove
humidity. as it costs more for unit to start up
as compared to what it costs for it to run.
you want less start up and long run time.
short cycling adds to your operating costs.
equipment life is shortened.

smaller units, sized with load calcs save you on
equipment costs, but more importantly utility costs
and more dehumidification. dehumidification is
very important in our climate.

one way to deal with oversizing is variable speed units. these units have the capacity
to heat/cool on the 10 days a year you have lots of
company, but also run in low speed for the rest of
the time.

low speed removes more humidity, and increases the
efficiency.

I find 15 to 17 SEER to be our sweet spot. less
and operating costs are high, dehumidification is
less. higher SEER has diminishing return on roi.

have a conversation with the company about variable
speed. dehumidification needs, smaller equipment
and mastic sealing of ductwork.
if they want a satisfied customer they will be
willing to spend a bit more time on your install.

you might also explore the option of heat pumps.
the upcharge will be less than gas furnace.
but will depend on electrical capacity & configuration.

the ducts and heating system are in the attic?

best of luck.

1. The prices seem high when you consider you are getting 80% AFUE furnaces, no replacement of linesets, and no extended labor warranty. Is Trane offering a rebate? Is the contractor offering a price break for installing two systems at the same time?

2. I have also read the negative comments on the XL16i. The argument is most problems can be traced to incorrect installation. If your contractor is a factory authorized dealer then you should be OK.

3. Linesets which are accessible should be changed in my opinion. If they are flushed, then you have to trust the contractor this he is following the manufacturer's procedures.

4. Trane is not known for their thermostats. There may be a better Trane model available. Discuss the options with the contractor.

5. If you plan to live in your house for several years, then an extended labor warranty would be a good investment.

I know it gets hot in Houston, but 7 tons seems oversized. What sizes are the furnaces?