new to forum, 2 systems of one?

[taatjben]

Hello -

My boss may fire me. I've been on your site for an hour already today.

I'm a homeowner, with a 2850 sq ft house in Minnesota (yes it does get hot here) Looking for general advice on a air conditioning system. Currently I have a central air handler unit in the basement with duct work in the floors which cools all but the three bedrooms upstairs which relay on an ancient split unit in the wall in the hallway. No heating with ductwork, I have hot water baseboard heat.

My questions is this: My basement unit that cools the majority of the house was put in in 1991, still works fine. However, I recently got a qoute to add a air handler in the attic over the bedrooms and a outdoor condensing unit. THis would be set up on a seperate thermostat, and just cool the bedrooms. WOuld I be better off putting a larger unit in the Upstairs and adding flex duct to the rest of the house and replacing the old basement unit? Is it more efficient to just have one central air sysem thats larger or two seperate ones?

Thanks for your help.

[old yeller]

Originally posted by taatjben
Hello -

My boss may fire me. I've been on your site for an hour already today.

I'm a homeowner, with a 2850 sq ft house in Minnesota (yes it does get hot here) Looking for general advice on a air conditioning system. Currently I have a central air handler unit in the basement with duct work in the floors which cools all but the three bedrooms upstairs which relay on an ancient split unit in the wall in the hallway. No heating with ductwork, I have hot water baseboard heat.

My questions is this: My basement unit that cools the majority of the house was put in in 1991, still works fine. However, I recently got a qoute to add a air handler in the attic over the bedrooms and a outdoor condensing unit. THis would be set up on a seperate thermostat, and just cool the bedrooms. WOuld I be better off putting a larger unit in the Upstairs and adding flex duct to the rest of the house and replacing the old basement unit? Is it more efficient to just have one central air sysem thats larger or two seperate ones?

Thanks for your help.

No- go with two units if you are cooling multiple levels. you will never get the balance right with 1 system unless you zone properly.

[taatjben]

IT SEEMS TO ME THAT RUNNING TWO SYSTEMS, EVEN IF THEY ARE NOT BOTH RUNNING AS HARD OR LONG, WOULD BE MORE EXPENSIVE THAN HAVING ONE SYSTEM? aT LEASE FROM AN EFFICIENCY STANDPOINT. ANY THOUGHTS?

[BaldLoonie]

For comfort, you are better off with 2. For efficiency, probably better off with 2 also. PROPERLY SIZED!

[johnsp]

A single zoned system can be more efficent, but that's gonna involve all new ductwork to do it right. You're probably better off just staying with 2 systems.

[beenthere]

2 systems.

A little redundencey is a good thing.

[markco]

Check out the possibility of a mini-split system. You could have each bedroom have it's own zone, so to speak. All hooked up to one condenser. Lots easier to install than an air handler in the attic. Also consider a mini-split heat pump. In moderate winter temps, it would heat each zone (bedrooms) to each persons comfort. And it would be temporary back-up heat it your boiler goes belly-up.

[Edited by markco on 06-25-2005 at 12:16 AM]