Air Conditioning - central A/C or Window units

Hello, can anyone tell me if its better to go with central a/c or window units?
I just bought a 3 bedroom house in pasadena, md. It has a kitchen, living room and lundry room. It's 960sf. on a slab, 12windows, 2doors (one has a window). We replaced old gas furnace with a trainie gas furnase (80% 80K btu) in january and decided to wait till this summer to add the AC. The house currently has a window unit in the kitchen. It keeps the living room and kitchen cool during only during rainy/over cast days. Not the back bedrooms at all except at night. Is it better to add another window unit for one of the back bedrooms and fans in each room or get central a/c?

By the way I don't see any kind of water leakage coming from the window ac unit. The unit fits nuggly inside a 32" window.

What is "better" depends. Central air is more energy efficient and uniform, but a lot more expensive. How much insulation does the house have, especially in the attic? Do you have ceiling fans? How well is the attic ventilated? Not an idle question - I just bought a house not terribly far from you (Easton) that has a ridge vent but no (none, zero) soffit or gable vents. The attic gets HOT.

The point is, there are a number of things that can be done to make the house cooler short of installing central air.

Thank you, any help is great. I'm a 1st time buyer.

My attic has one layer of the roll out insulation and no fan. Are you saying that hot air trapped in the attic can make the house hotter? Also you mentioned energy efficient, my house was built 1960 and the duct work is in the slab. Do you think my bill will differ $75-100 more with another window unit vs central A/C?

Oh yes: the hotter the attic, the hotter the whole house. If it were my house the first thing I'd do is put more insulation up there. I don't recall exactly, but I think the recommended amount for our area is R-39 or so. If you have a single layer put in when the house was built, you're lucky if you have 1/3 of that. It won't cost a whole lot for such a small house and is simple to install.

There are too many variables for a precise answer, but I don't think your bill would go up anywhere near $100 a month by adding a window unit. Or with central air either. My house is 2-story, 1500 square feet, built the same year as yours. I have two window units, and my TOTAL electric bill is around $60 a month. I have R-46 in my attic.

$60 in the middle of summer and winter too!?

So, it does not hurt if you have more insulation in the attic than recommended so long as it is well ventilated? Also is your house on a slab?

No, it certainly doesn't hurt to have more insulation. The more the better, up to a point when the payback would be a lot of years. If you want to add more layers, just be sure the insulation is unfaced. You only want one vapor barrier.

Don't let my $60 electric bill fool you - Easton Utilities is the cheapest electicity in the State by far. Also, my wife is paranoid about spending money on "frivolous" things like air conditioning and heating (she grew up poor on a farm). I've put ceiling fans in all four bedrooms so we haven't even used air conditioning yet this year. And in winter the thermostat's set on 60 degrees. Also, we have oil heat.

And yes, my house is on a slab.