DX capacity lower than condensing unit

[M.Saleh]

I have DX unit which capacity 30.8 Kw install with condensing unit which capacity 39.3 Kw . DX capacity lower than condensing unit , Is this a problem ?? What's this problem ?? How can repair this problem ?

[flyinkiwi]

Suction pressure & evap temp may be lower than DX coil design conditions, resulting in excessive dehumidification.
One way to resolve this is by fitting an EPR.

What are the rating conditions for the condensing unit?
Is it possible that the condensing unit has been selected to match the evap at a higher amibient (and SCT)?
Does the condensing unit have any capacity control?

[Magoo]

Hi M.Saleh.
Depending on the design selection of evaporator and compressor conditions. Most manufacturers of evaps state performance for say a freezer coil at 4'C diff between air on and evaporating temps. Add to that the suction line losses bends accumulators valves crankcase regulators, the compressor suction will be /could be 6 'C lower, for a balance to evap., capacity.
So if you compare an evap duty at -18 'C room temp and at compressor duty of -18'C the Kw /HP could be hugely different to evaporator. To compound problem design engineer could have selected a bigger evap TD at say 6.0 'C.
So there goes a comparison imbalance.
magoo.