To debunk the myth that over sized ACs reduce energy consumption, here are two links.
Oversized ACs won't cool your room better. Rather the opposite.
https://www.airconditioningarizona.com/bigger-tonnage-ac-wont-cool-better/
And, undersized ACs dehumidify rooms better than even standard sized ones.
https://michaelsenergy.com/briefs/undersize-ac-for-efficient-dehumidification/
In BD, humidity is the killer.
And let me summarize the points here.
1. The AC going short-cycle mode -- when it has cooled the room enough and is turning on and off periodically to keep it such -- is less power efficient than running long.
2. Dehumidifier works like gradual "reduction by a percentage" basis. Therefore the longer you run it, the better it performs. An oversize AC will cool down the room quickly and stop. And can't run any more to dehumidify, as the room is already too cool and running it longer will make it excessively cool. Yet humidity is high, as the AC ran for shorter duration. And you are thus uncomfortable.
3. Also note air-circulation within the room to cool all corners take time. A high tonnage AC will cool the air in front of it too quickly, while rest of the room hasn't had time to balance.
Therefore high tonnage AC isn't either comfortable, nor power saver, nor economically cheaper.
You are basically paying higher for worse.
BUT,
AC manufactures and salesman will give you the opposite idea, as their profit is proportional to the size of AC they sell you.
While,
Maintenance engineers will give you a different idea as their job is to help you get efficient and get more for your bucks.
- Comments:
- Use half the size proposed by the AC dealer. Therefore if it's a 200sqft room, use 1 ton. 400 sqft? Use 2 ton instead of 4 ton as they will propose.
Now it all depends on need. For a mosque where rapid cool down is required as the AC will run for a short period of time, you might go for high tonnage. For resident home, use the advice I put above.