Summer’s comin. Now that I can afford to get an air conditioner, I think I will, as last summer was rather hellish. Anyway, I calculate the size of the portion of my apartment that I want to cool at about 300 square feet. According to one air conditioner calculator I found, I need about 8400 BTU’s, but that seems pretty high. I don’t want to overdo it. Electricity is expensive in these parts.
Some relevant info:
The rooms have good curtains that can block sunlight. The ceilings are high (about ten feet) so the volume of air in the room is bigger. (Perhaps a more accurate calculator would ask for cubic footage?)
I would use the figure from the site after checking around with various dealers. Assuming the figure you give is correct, get one slightly bigger, like a 10000 Btu/hr. unit. Just because you have the capacity for 10000 doesn’t mean that your electricity bill will be higher. The unit will only run as much as required to actually cool the premises. The added cost for the bigger unit is only in the original price, not in the use of it. That assumes that the big unit and the small unit have the same efficiency. If you buy one that is too small, your room will not be cooled and nearly all of the first cost plus the operational cost is wasted because you aren’t getting what you pay for, i.e. cooling the room.
Well, maybe. I’d like to see the site’s justification for the claim though. It is true that if you run a machine at some output off the efficiency peak, the operating cost goes up. For example, a 2 hp. electric motor putting out only 1/4 hp is probably costing more to run than, say, a 1/3 hp motor doing the same job.
However, air conditioners are bang-bang systems. When they run at all, they run at the designed output, which for well designed units is probably in the vicinity of best efficiency.
And, of course I didn’t recommend one that is grossly oversized.
I’m not qualified to comment on the “cool too quickly and leave excessive moisure in the air.” I’m don’t even I understand it.
Simply put, an air conditioner dehumidifies by drawing room air over its cooling coils, and the moisture condenses out. However, if the unit cools the room off too quickly it doesn’t have time to recirculate all the room air, leaving considerable moisure still in it.
It does circulate some of the room air, of course. The greater the cooling capacity of an air conditioner, the less time it needs to run to cool the room to a given temperature, so less of the room air gets recirculated.
Well, what the OP poster needs to know is how big a unit to get. Follow the recommendations of the various sites. I would average them and get one slightly bigger than that. Don’t go overboard on how much bigger. But I still say that I think you will be a lot more satisfied with one that is slightly too big than you would be with one that is slightly too small. The difference in first cost is small. If there is any difference in operating cost because you are a little too big it will be so small as to not matter. When you cool the room down, the relative humidity will go up, that’s just a fact of life. The A/C will remove a certain amount of moisture but not all of it.
