Many years ago we bought a duplex on a lake, and converted it into a single family home by taking out walls and a staircase. It's now a 2 story home, all bedrooms upstairs, all living areas down. It is located near Memphis, Tn.

Since it was built as a duplex, it has a separate unit for each side, but is not zoned for up and down.

The hvac units are all old now, and we're doing some other renovation, so it is my intention to pretty much start over with the hvac.

Our issues with the current setup are:

1. I think it's inadequate. It recently took 20 hours of running to cool the inside temp from 80 down to 72.

2. We can't get the temp comfortable for both upstairs and downstairs.

3. Since it's a vacation home, we like to go over on a Friday after work sometimes. I leave the units off when we're not there, but they can't cool the place down, as in note 1. I do have a land-line, but no internet hookup there.

It occurred to me that we could install motel units downstairs, to provide the extra kick it takes to cool the place down initially, and / or maybe zone for upstairs and down.

We're at an age now where we're going to indulge ourselves and do the job properly, so I'm looking for advice. My HVAC man at the lake says "start over with a single system zoned for up and down that you can call ahead and get cool before you show up". I don't know if that's the best route or not, so seek advice.