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1002594 ISSUE 1 M172 VARIHEAT
VARIHEAT AW SYSTEM OWNER INSTALLATION MANUAL
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 section 5.0 Variheat
DATA SHEET on page 56) 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 with a
clean filter if fitted. This differential pressure will drop as the filter becomes dirty.
Provided the filter is cleaned before the minimum differential is reached (which
would normally be the case with a well managed system) then no problems
should be encountered.
Setting up the differential
When 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. Note the System Pressure on both gauges – they should read the same,
but due to manufacturing tolerances they may be different.
3. Switch on water circulating pump.
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
section 5.0 Variheat DATA SHEET on page 56) 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 section 5.0 Variheat DATA SHEET on page 56 for correct water
pressure drop.
Determining water flow
Summary of Contents for Variheat AW1200
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