DETERMINING WATER FLOW AW3034/7034H
a Flow Meter Method (see fig 3).
Ensure isolation valves ‘A’ and ‘B’ and bypass valve ‘C’ are fully open. Slowly
close down bypass valve ‘C’ until correct flow rate is shown on the flow meter.
(see data sheets pages 28 to 30) Remove handle and lock off valve ‘C’.
b Differential Pressure Method (See fig 3)
.
By simply installing two filter pressure indicating gauges, one each on the
inlet and outlet of the heat pump, and a locking type gate bypass valve
in the bypass line, the flow rate through the heat pump can be accurately
determined by the difference in the readings of the gauges.This pressure drop is
proportional to flow.
Flow rate should be set at the maximum differential.
Setting up the differential.
When the installation is complete, the procedure for setting the flow rate
through the heat pump using two gauges is as follows:
1. With the heat pump switched off, ensure isolation valves ‘A’, ‘B’ and bypass
valve ‘C’ are fully open.
2. Switch on water circulating pump.
3. Note the water System Pressure on both gauges - they should read the
same, but because of manufacturing tolerances they may have different
readings.
For example; with a water system pressure of 5mhd the gauge on the inlet
may read 5 and the outlet gauge 5·5 therefore there is a STATIC ERROR
DIFFERENCE of 0·5mhd.
4. Gradually close the bypass valve ‘C’ until there is a difference in pressure
between the two gauges that is equal to the required pressure drop (see data
sheet) observing any static error on the gauges before beginning this process.
5. Lock the bypass valve, or render it tamper proof, when correct setting is
achieved.
6. See data sheets pages 28 to 30 for correct water pressure drop.
9
SD331851 ISSUE 28
