Guide To Pool Heating

Page 51 of 51

Alternate Method to Calculate
Total Dynamic Head

Useful when a vacuum gauge and/or pressure gauge is not available and
you want to get a general picture of the pool’s dynamic head for checking the
pump sizing when adding a solar panel system or the SolarAttic Pool Heating
(PCS1)

A. Vertical Lift= 20 feet

Estimate the distance in feet from the pool’s pump to the top of
the solar panel system or to the inlet of the PCS1.

B. Suction Lift= 10 feet

Estimate the distance in feet that the water is lifted from the
bottom of the pool to the pump’s intake.

C. Horizontal Pipe= 200 feet

Estimate the total horizontal distance from the pump to the
solar system. This is the distance oneway.

D. Total Horizontal Run= 2 times the
horizontal pipe.

CALCULATION:= 200 x 2 = 400 feet of pipe

Calculate the total horizontal pipe run from the pool’s pump to
the solar system.

E. Pipe Friction Loss per 100 feetof
pipe = 5

Obtain the friction loss in feet of head per 100 feet of 2 inch
Schedule 40 PVC pipe at 55 gpm flow rate. Loss increases if
flow rate increases. You have to measure or estimate the flow
rate. See prior table for the friction loss of pipe (per 100 feet).

F. Horizontal Friction Loss =
Total Horizontal Run ÷ 100 x Friction Loss per
100 ft

CALCULATION:= 400 ÷ 100 = 4 x 5 = 20

This calculation provides the friction loss caused by the
horizontal pipe run within 2” pvc pipe at 55 gpm.

G.Total Dynamic Head=
Vertical Lift + Suction Lift +
Horizontal Friction Loss

CALCULATION:
= 20 + 10 + 20 = 50 feet of head

Total Dynamic head is expressed in feet that the pump must
operate against. This simplified formula ignores the effects of
the pools pipe fittings. See prior method for a more accurate
calculation of dynamic head.

H. Nominal Pressure= 50 ÷ 2.31 = 21.6 PSI

Nominal Pressure in System = (Total head ÷ 2.31)

I. Pipe flow rate estimate= 50 gallons per
minute

Measure or estimate of flow rate. Derated with the above
conditions and ideally obtained from a pump’s performance
characteristic curve. You can obtain such a curve from your
pool dealer or pump manufacturer.

J. Gallonsin pool = 28,000

Measure or estimate of pool gallons.

K. Turnover= Gallons ÷ Flow rate.

CALCULATION:= 28,000 ÷ 50 = 9.3 hours

How long it takes to turn over the water in the pool as a result
of the above projected pipe run/friction and the pump’s curves.