Cylinder Reheat Calculator
How long will your heat pump take to reheat the hot water cylinder? Adjust the inputs below to see the energy required and the estimated reheat time.
Inputs
7kW
Available output in domestic hot water mode.
2 kW20 kW
250L
100 L500 L
10°C
5 °C20 °C
50°C
45 °C60 °C
Cylinder
Cold inlet Energy added Stored hot water
Results
Estimated reheat time
1 hour 40 minutes
1.66 hours at full output
Energy
11.6kWh
Heat pump
7kW
Temp rise
40°C
How this works
Your cylinder contains a fixed amount of water. The heat pump must add enough energy to raise this water from the incoming cold water temperature to your target hot water temperature.
250 L × 40°C × 0.001163 = 11.63 kWh
11.63 kWh ÷ 7 kW = 1.66 hours
This calculator provides an estimate only. Actual hot water reheat times depend on heat pump operating conditions, cylinder coil performance, system design, flow rates and control settings.