How do I size my pool filtration pump for use with a DualSun solar heating system?


Key point to check: Does the filtration pump deliver sufficient head (HMT) to push the water up to the solar installation while maintaining sufficient filtration flow from the pool?

Calculating the HMT:

The solar installation generates additional pressure losses in addition to those of the filtration circuit of the pool.

In an open circuit at atmospheric pressure, the pump head must be greater than or equal to the sum of the pressure drops of the circuit and the height of the water column to be pushed:

HMTpump [mCE] ≥ Hinstallation + PDpanels + PDfilter + PDline load + PDsingular + PDaux

  • Hinstallation = height in meters between the highest point of the hydraulic circuit and the filtration pump

  • PDpanels = see Spring technical datasheet Appendix - Pressure Drop

  • PDfilter = 10 mWC (Pressure drop of a dirty sand filter, with safety margin)

  • PDline load = 0.02 mWC x total length of piping in meters

If the exact length of the pipes is not known, the total length can be approximated by:

L = 2.5 x Hinstallation

  • PDsingular  = 0.4 x PDline load 

  • PDaux = when using a heat pump or other auxiliary heating system, add its pressure drop

How can I check that the HMT of the pump is sufficient?

Consulting the performance curve in the filtration pump datasheet makes it possible to determine the value of the HMT at the required filtration rate.

Recall from the calculation of the filtration flow rate:

The filtration rate is usually calculated on the basis of a total recirculation of the volume of the pool in 3.5- 4 hours. Due to the additional pressure drops induced by the solar installation, it is necessary to retain the high flow rate value:

Qfiltration [m3/h] ≥ Vpool / 3.5