A company has installed a heat pump style pool heater for a client who has complained that it just doesnt reach temerature ( 30.5 degrees C).
I am trying to increase the capacity as much as i can without changing any components. The suppliers of the heat pump have said that i should decrease the water flow rate through the heat exchanger? This they say will increase my head pressure and increase the temperature difference across the heat exchanger. 'This would increase my capacity.' While this initially sounded right i now, after thinking about it, disagree. If we lift our HP the compressors capacity decreases. At the moment we have a 47 degreeC HP with a water in of 27 and out of 30.

Shouldnt we rather increase the water flow rate through the heat exchanger , lowering our HP , which is an increase in capacity?. Even though our HP is lower and our TD will be less due to the increased flow rate and the improved compressor capacity will be an overall system improvement?

In other words if I lower my HP from 47 degreesC to 40 DegreesC I increase my compressor capacity from 20kw to 25kw. This i can acheive by increasing the water flow rate which increases the capacity of my water cooled condenser.

Therefore having a Standard 40 DegreeC head pressure with its corrosponding flow rate is better from a heating capacity point of view than a high head pressue with its slower flow rate???