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4. DETERMINING WATER FLOW
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 (see
data sheet page 26) is shown on the flow meter. 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 sheets on page 29) 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 (page 29) for correct water pressure drop.
SD566251 ISSUE 36
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