Inquiries about daikin dx ducted concealed units

[Ahmed Kassim]

i have an outdoor unit with cap.5 TR installed with an indoor concealed unit cap.4 TR .
the question is , is it possible to install units (indoor/outdoor) with different capacities ????
and if it can't be possible , i need to know why?

 

[lukaiENG]

That would be a question for your equipment rep. In theory yes it should be possible, often you would want to upsize an outdoor unit as the capacity may be de-rated due to temperature (for example)

 

[dbill74]

The short answer is yes, different sized indoor/outdoor units can be installed together in split Dx system.
This is because the listed capacities are what the units are rated for under specific testing conditions.
Doing so will have a mojar impact on the performance of the system.

BUT they have to be close in size. You can't use a 4 ton indoor unit with a 7.5 ton outdoor unit for example. The min/max flow rates of the two pieces of equipment are not compatible.

 

[Ahmed Kassim]

thank you all for your response , but i have a big problem in some site which has 13 units with specs like what i mentioned before and non of them works properly , the conditioned spaces are very hot , you can not feel any airflow at all , so i was thinking that different capacities may be the problem .

 

[dbill74]

you can not feel any airflow at all

Where are you feeling for air movement? Just because you can't "feel" anything doesn't mean there is no air movement.

As for why the spaces are hot, there could be many reasons for that. You are going to need to do some troubleshooting. Start by checking load calculations.