We can't *see* it from here. Call your local, *competent*, licensed,
insured, professionally trained, HVAC technician to do a complete assesment
of what your home requires so that it can be fitted with a complete comfort
system and what the cost vs payback is for you home.
In this neck of the woods, the payoff is pretty quick (roughly 5 years) for
a complete high efficiency comfort system.

"Nehmo" wrote in message
...
If a house currently has multiple window air-conditioners, are these
significantly less efficient than central air, if the house were
retrofitted with it?

I realize the comparison is complicated, so assume all other factors
equal, and assume: the vents and their position for central air would be
adequate; about half the rooms are normally in use; nobody's concerned
about the window-view obstruction, etc.; Chicago climate; poorly
insulated house.

A companion question is, does the efficiency of air conditioners
increase significantly with size?

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