Guide To Pool Heating

Page 50 of 51

TOTAL DYNAMIC HEAD CALCULATION

USING A PRESSURE GAUGE AND VACUUM GAUGE

Make sure the filter is clean when the pressure gauge and vacuum gauges are read.

The pressure

gauge is typically on the top of the filter and measures the pressure on the output of the discharge
side of the pump. Therefore, the pressure gauge is a measure of the head loss on the discharge
side. The vacuum gauge is placed on the pump’s intake suction side to measure the head loss on
the suction side. Both numbers have to be multiplied by conversion factors and then added to get
the total dynamic head. This method is the most accurate because you are measure the results of
your existing system. Why go to all this trouble measuring/calculating? To verify proper sizing of
your pool’s filter and pump. Especially if you have problems with pool cleanliness.

Step 1

Multiply the pressure gauge reading times 2.31. This equals the head loss on the
discharge side of the pump.

Step 2

Multiply the vacuum gauge reading times 1.13. This equals the head loss on the
suction side of the pump.

Step 3

Add the two totals together to obtain the total head loss in the system.

Example:

Pressure gauge reads 20 pounds. Vacuum gauge reads 10 inches of mercury.
Therefore

Pressure gauge

20 x 2.31

=

46 feet of head

Vacuum gauge

10 x 1.10

=

11 feet of head

Total Dynamic Head

=

57 feet of head