Need to install multi split airconditioning. Need help with units config,specs

[Kozanostra]

Hi all.
In a new apartment ,in a new building with newest cost saving isolaion standards the investor has installed only one indior unit and outdoor unit 12000btu , now I need to change it to multi split with three indoor units.
Livingroom is 200sq ft
1st bedroom is 150sq ft
2nd bedroom is 100sq ft

They say the holders for the outdoor units cannot be changed for newer bigger 9nes ,for bigger units cause the building cannot be modified..so the holder needs to be the same.
I don't understand much about hvac, but I understand the indoor unit s BTU total should be the same with the outdoor capacity.
The apartment is on 5th floor, south orientation.
Can I get 27000 btu outdoor+
7000 for the 100sq ft,
9000btu for the 150sq ft
And 9000 or 12000 btu for the living room?

I never plan to use all three indoor units at same time..
Maximum usage would be livingroom+ bedroom at same time..
And that would be afternoon hours..
Winter time, heating 8am-10pm
Summer time 3months cooling approx 11am-5pm.

Can those specs be enough for 2 units, regardless of if I have 3 units that exceed in total of the outdoor unit, or I need to get 27000btu outside unit and somehow modify the holder of the unit?

Thanks!

[HarryStin]

Hi all.
In a new apartment ,in a new building with newest cost saving isolaion standards the investor has installed only one indior unit and outdoor unit 12000btu , now I need to change it to multi split with three indoor units.
Livingroom is 200sq ft
1st bedroom is 150sq ft
2nd bedroom is 100sq ft

They say the holders for the outdoor units cannot be changed for newer bigger 9nes ,for bigger units cause the building cannot be modified..so the holder needs to be the same.
I don't understand much about hvac, but I understand the indoor suika game unit s BTU total should be the same with the outdoor capacity.
The apartment is on 5th floor, south orientation.
Can I get 27000 btu outdoor+
7000 for the 100sq ft,
9000btu for the 150sq ft
And 9000 or 12000 btu for the living room?

I never plan to use all three indoor units at same time..
Maximum usage would be livingroom+ bedroom at same time..
And that would be afternoon hours..
Winter time, heating 8am-10pm
Summer time 3months cooling approx 11am-5pm.

Can those specs be enough for 2 units, regardless of if I have 3 units that exceed in total of the outdoor unit, or I need to get 27000btu outside unit and somehow modify the holder of the unit?

Thanks!

you can get away with a 12,000 BTU outdoor unit, which is the same as your current one. You just need to replace the indoor unit with three smaller ones, such as 7,000 BTU, 3,000 BTU, and 2,000 BTU.