Heat pump & heat exchanger calculator

Calculate heat output and COP for a system with a counterflow plate heat exchanger between the heat pump and the radiator system. Calculation based on effectiveness NTU method [1].

Room temperature

Outside temperature

Heat output

Heat exchanger heat transfer rate

Heat exchanger Area

	Heat pump side (Primary)	Radiator side (Secondary)
Flow rate	L/min	L/min
Heat capacity	J/kg.K	J/kg.K
Flow temperature	°C	°C
Return temperature	°C	°C
Mean water temperature	°C	°C

Rated radiator output [2]

@ Rated deltaT (MWT - Room)

COP Method

Heat pump COP

Comparison with open-circuit system without a heat exchanger:

Heat pump COP if driving radiators directly without the heat exchanger (Flow: {{ app.Tco | toFixed(1) }}°C, Return: {{ app.Tci | toFixed(1) }}°C):

or direct radiator output at the primary flow temperature: {{ app.Thi | toFixed(1) }}°C, return: {{ app.Tho_direct | toFixed(1) }}°C and COP: {{heatpump_COP | toFixed(2)}}

[1] Effectiveness NTU method, implementation here ported from python CalebBell/ht library.

[2] 15000 W @ 50K = 7x 1200x600mm K2 double panel radiators, each with an output of 2145W @ 50K.

[3] Carnot COP equation based on +4K offset on flow temperature, -6K offset on outside temperature and a practical efficiency factor of 50%.