[retiredguy123]

Originally Posted by Malsua

I just want to chime in a little. I am a licensed, certified, insured and bonded home inspector and I have inspected north of 500 homes here in TV.

In the past, I did a lot of industrial work, including, but not limited to installing boilers and HVAC equipment both commercially and residentially.

There is a method to calculate your home's HVAC requirement, emphasis on the AC, and it's called a Manual J. It is a long, sorta complicated method but it'll come out accurate.

You don't have to do this though as it's already been done for the home you live in. Unless you have altered your structure, the size of the heat pump or AC you have(if you have a furnace as well), is what you should stick with.

I have inspected two homes this year where the home owner was from up north, and wanted the house to be 71 during the day and 66 at night. While not such a problem in January, when they come down in July, it's not going to happen with the original condenser.

In both cases, they got larger units.(i.e. 1 ton larger and 1.5 in the other) In both cases, the units short cycle most of the year(both inspections were in the spring) and the humidity in the home was never controlled properly. The system wouldn't run long enough to get the humidity out before set temp was hit.

The other issue about running 71 degrees while it's 93 with an 80% relative humidity is that every leaky spot in your house will be found after a while as the paint flecks off and the wood trim around the windows and doors starts to rot from all the condensate. Yes, when you sell, your home inspector will find it.

You can typically upsize half a ton without too much drama, but if your current size does not struggle in July, that's the size you should keep.

One final thought. Of all the homes that are 15+ years old and still have the same system? The brand is pretty much always Trane. I have seen one 21 year old Carrier system and probably 25 Tranes that are 20+. My neighbor has a 26YO Trane.

If your last paragraph is trying to conclude that Trane is a better unit than Carrier, I would disagree. In the past (I think 15 to 20 years ago?) the developer installed only Trane, and then they switched to Carrier. This would account for there being more old Trane units than Carrier units. Also, the units being produced today have very little to do with the quality of today's products.