You have a quote for 7 tons of cooling and furnace size 200,000 BTU input (160,000 BTU output).

Has this contractor done a heating and cooling load calculation? How big is your house and does it have any insulation? What are the sizes of the current furnaces and condensers.

The Carrier Infinity is good equipment. There is no comparison to Payne, and in my opinion worth the extra money for a comparable Goodman unit.

If you are going to buy an Infinity AC and/or furnace you should be the Infinity controller. You are wasting your money by trying to control it with a cheap thermostat.

Thanks for replying. My AC guys said that since I order a single stage single speed there is no need for a fancy thermostat. Only thing I get is reminder of when to replace filter and network connection for remote control. Is this true or is he totally wrong?

Forgot to add:

The system is a replacement same tonnage of the old one. I have yet to have a total inspection from the contractor. House is 3200 sqf. Insulation is adequate, double pane window etc.

Overdoze - there aren't many (if any) places in the country where that would be a reasonable size based on "adequate insulation".

Where are you located and have they done a manual J. When you run the a/c or furnace before, do you have any idea what the average cycle length was. While 16 years isn't bad, you might have lasted 50% longer if you weren't so (presumably) grossly oversized.

David, Thanks for replying

It is R19 wall, R30 in the attic.

I have yet to ask contractor to do a manual J. The A/C is still working great. I could just replace the coil and continue using it. I just want to replace to save electric since the old system is not as efficient as it used to be.

It runs for about 15 mins then it stop.
The air comes out the vent is 15F below intake air.
Been running the A/C 24/7 for 6-7 months out of a year.

Any time you have an installer that wants to install Infinity equipment without the Infinity T-Stat - RUN!

SR

"Condenser 24ANB636A-3 24ANB648A-3"

These are 2-stage condensers. If you don't use a 2-stage thermostat, then the stages will be controlled by a timer on the control board of the furnace. The AC will operate in the low stage for a few minutes and then always run in the high stage.

These prices are pretty low. Do you have confidence in this contractor? So far he has given you some bad information.

Greatful for all your input.

Never have experience with them. Run accross when I am doing bidding for new AC. They are A+ on BBB, on Angies list, Nate, and a factory authorize dealer on Carrier website.

I have him come out Saturday to inspect the house. Will ask them about the infinity Thermostat instead.

Will let you know how it goes.

I'd recommend a Carrier Infinity system including thermostat and media air filter.
Go thru a factory authorized Carrier dealer and Carrier has a fall rebate deal on Infinity system installs starting Sept 1, up to $1350 rebate.
I found I got a lower priced quote from a good A+ rated Carrier dealer with the rebate compared to Amana/Goodwin dealer quotes for an Infinity 2-stage 18Seer AC + Gas Furnace system.

The inspection is done. Basically, The 2 systems are ok for the home. There will be 2 new return air installed one for each system. The older one is too small. The older Airtron systems are actually a 4 tons and a 2.5 tons

They open the book and show me the part number for the condensers. Both condensers are single stage according to the book. Can someone provide me the specs to those condensers or double check?

After rebate the total cost with 2 new media filters system, 2 new infinity thermostats, 2 new return air vents is $11,700

My mistake, and you are correct the 24anb6 condenser is a single stage. The 24anb7 is 2-stage.

Sorry for the confusion.

I have the downstair 4 tons replaced today. The contractor will come back for the second unit (upstair) tomorrow.

I notice a few differences. The good one is the condenser is very quiet. The air temperature difference between return and vent is 20F. What I'm concerned about is the humidity from the vent is 80%. When I go upstair and check the old unit the humidity is 50%. Normally my house have humidity level at around 43% with the old unit.

Feedback on what I should do or check please

How long are the cycle times on your downstairs unit? What is the indoor temperature setting? What is the cycles per hour setting on your thermostat?

My suspicion is your downstairs unit is oversized and short cycling even though your old unit was also 4 tons. The new unit with the new return is providing more cooling than your old unit. You are now going to replace to old 2.5 ton upstairs unit with a 3 ton condenser. You will probably have a humditiy problem upstaris as well.

You need to speak to the contractor before he does any more work.

Thanks Mike.
I talked to the contractor about it. It turns out there is a heatwave in Texas. One system was down for too long, when finally on it runs continuously for 6hrs just to cool the house down and the contractor did not place any filter in to speed up the cooling.

Today, both system are completely done. It is wonderfully quiet and cool properly as well. It took 4hrs running to bring the house to desired temperature. 2 more hrs pass. It is now 102 outside and 78F inside as I set it.

The system cycle time is set to 4 times per hour as default by factory.

One more good news is they are giving me a cash bonus as well. So I end up paying only $11k for both system before $500 factory rebate.

In turn it cost only $10,500

If I were to get the 2 stage systems 19 seers, it would cost me 2K more.