central air ducts at the floor

[plarian]

I'm looking into air conditioning for my house, it has 660 sq ft on the upper floor and about 330 sq ft downstairs. Only the upper floor gets hot, so I don't need much.
I'm thinking of central AC or a mini-split. I have forced air gas heat, so there are heating ducts already. The heat comes out at floor level.
If I got central AC - does it cause a problem if you use the heating ducts and the cold air comes out at the floor??? I would think it would just sit there and make your feet cold, while there's a layer of hot air higher up?
Is central AC available that wouldn't be oversized for me? I would get one with a variable speed fan.
My main objective actually is to lower the humidity to below 50%. But I think I need AC to do that. Right now I open the windows at night to cool down, but if I were keeping the humidity low I wouldn't be doing that and it would be pretty hot if I were keeping windows closed and just dehumidifying.
Thanks for all the advice I've gotten in the forum. I've dehumidified the bottom floor with a couple of portable dehumidifiers.
Laura

[beenthere]

Depends on your duct system on how well the air comes out.

When your furnace runs in heat. Does the air blow out, or is it barely noticable.
They make 1 ton central A/C units.

[plarian]

Depends on your duct system on how well the air comes out.

When your furnace runs in heat. Does the air blow out, or is it barely noticable.
They make 1 ton central A/C units.

It heats up my house quickly in winter. I turn the heat off at night and it heats up quickly in the morning. My heater fan is about 1000 CFM, or it used to be
Laura

[beenthere]

Doesn't quite answer teh question.
But, registers in the floor are common here for heat and A/C.

[plarian]

Doesn't quite answer teh question.
But, registers in the floor are common here for heat and A/C.

I'm not sure what you mean, then. They're baseboard registers actually. Air comes out strongly or not, depending on how the vent dampers are set. But an AC would be using its own fan anyway, not the heater fan, I suppose. 1000 CFM for 660 sq ft seems like a lot of air circulation. I can set the vent dampers so it's not circulating air through the cooler bottom floor.
So, there shouldn't be a problem with cooled air coming out at floor level? I know this is done, but I don't understand how it doesn't just create a layer of cold air at the floor.
Laura

[tunnel_rat]

If the system is sized properly, floor registers shouldn't be any problem. They are very common around here as well.

[beenthere]

An A/C will use the furnace as the blower.

[obxtech]

Make sure any ducts exposed in unconditioned space are insulated, alot of old heating only systems were not insulated.

[firecontrol]

Call the company that services your furnace now and tell them you're interested in AC and that you'd like someone to come to your home and look things over, explain how it will work and what they can do for you. This way you can ask and get answers while you are looking at your system and each of it's components.

A properly sized central AC will dehumidify your home effectively and you will possibly be able to turn off the dehumidifiers in the lower level if there are vents down there from the main system.