You need at least 2 HP to feel "cold", or else just chilly and not hot only.

The air-cond compressor will be running non-stop in this circumstances.

If you wanna coolest, try for Daikin inveter 2hp you might not be regret at all, cause I got customer house same with the size, they install Daikin 2hp inverter can be feel that cold until kitchen area.

With your room/space condition that cool air will keep on escaping one, inverter saving won't be too obvious, as you may always need full blast from the air-cond, even for 2HP.

But still it is up to individual choice, both inverter and non-inverter have its own pro and con.

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A morning troll on my monthly TNB bill for 1.5HP non inverter(4 hours max, 20 days) and 2HP also non inverter(1-2 hours, 22 days) which all inverter fanboys won't dare to share out on their monthly bills, rather than keep on boasting out how superior their inverter are.
The air cond in your living hall shall be as near to your sofa(or place that you sit most of the time), don't expect to cool the whole hall like your room with just 2-3 hours. It won't able to as the surface area too big.
Also, if you install it on the red box, the cool air won't able to reach your dining hall. So the best place is install on the front wall, then it can blow till dining. Also it can reduce the piping length which will improve the efficiency.
With your usage, just get the non inverter will do, no need to waste money on inverter unless your usage is > 4 hours.

Hi, Daikin have new model of inverter air conditioner.