Can a higher capacity (BTU 18000) outdoor unit be coupled with a smaller indoor unit

[Geraldw]

can someone tell me whether i Can use a higher capacity (BTU 18000) outdoor unit be coupled with a smaller indoor unit?

will there be any efficiency gains by doing this?

thanks

Gerald

[moideen]

what is the capacity of indoor unit? indoor and outdoor should be matched.if the indoor capacity is low compare to outdoor unit,the evaporator temp.will go down resulting you cannot maintain the evaporator temperature and also would cause ice forming ,compressor flooding...etc.

[Geraldw]

the indoor unit is 12000 BTU

[nevinjohn]

Unless the manufacturer provides the option of having multiple indoor units, it would be hard. Consider the fact that the outdoor unit comes with a single discharge and suction line, which needs to be connected serially to suit your requirement. This means additional valves and refrigerent flow regulators so that each unit (In your case one 12000BTu unit, and the next 6000BTU unit) gets the required flow. It is possible when the manufacturer makes the units, but you cannot customize it. The next option is to have VRF units!