Hello Petetherock,
What you most probably need is either one of the below configuration depending on your usage trends and also room area:
1) System 4
2) System 3 + System 1 (separated system for hall and dining)
This configuration has 2 outdoor condensers
3) System 3 + System 2 (separated system with 1 indoor unit for hall and 1 indoor unit for dining)
This configuration has 2 outdoor condensers
Your appointed installer would be the one that can help you with these questions. Show them your floor plan and they will be able to calculate and advise the BTU required based on the individual square area of each room and make appropriate recommendations.
Sometimes factors such as afternoon/evening sun, design factors also comes into play so work with your installer or your ID on those.
As for the old Toshiba inverter (not too sure what you mean by 3 compressor and 5 head units. Do you mean 3 outdoor units and 5 indoor wall mounted units?) If these are working fine, you can consider to keep them depending on your budget. Noise would most probably be due to aging and maybe also dirt. If you intend to keep the old units then better to have it checked and chemically overhauled after renovation so that the units are cleaned thoroughly. Personally I would still prefer to have it replaced since renovation is to be done.
Good Luck on your sourcing.
Best Regards,
Jason Tham
Thanks for the replies..
I can only do reno at the end of August earlier, so that's good.
If they can remove the old ones, what should I be looking for a three bed-room place that also needs two / one unit for the hall / dining area?
Right now, there's an old Toshiba Invertor unit (three compressors for five head units?) . It worked well, but it was noiser than my non invertor Panasonic single unit.
Total area of my flat is around 1200 sq ft (including kitchen and the balcony.)