Check for leaks:
Before re-connecting all the tri-clamp fittings around the exchanger, it is necessary to
check for leaks by pressurising the product channels (which exist in all three sections
of the heat exchanger). Connect the feed pump to the product inlet of the exchanger
and place the flexible hose from the back pressure valve into the feed tank for closed
circuit flow. Place 2.0 litres of water in the feed tank. Start the pump with back-
pressure off and slowly increase to full speed. Adjust pressure to 6.0 bar and observe
all connections on end and intermediate plates for signs of leakage. If a leak is
occurring then either one or more plates are wrongly assembled or the studs are not
tight enough. It is always prudent to inspect the orientation of the plates before
resorting to tightening of the studs.
The stud nuts must be tightened evenly so it is advisable to tighten both finger tight
first then use a socket wrench or spanner/wrench to tighten one full turn alternately
and reduce this to half turns and quarter turns as the final dimension is approached. A
small quantity of a suitable grease applied to the threads of the stud will assist this
operation.
If the plate heat exchanger assembly is tightened below 88.0mm, the pressure drop
may be too great for the hot water circulation pump. This will cause the magnetic
drive to de-couple. To overcome this the by-pass valve at the rear of the hot water
reservoir will need to be opened slightly.
Replacing Temperature Sensors T1, T2 & T3
Temperature sensors T1 – T3 are sanitary semiconductor sensors.
If a replacement sensor is necessary this can be obtained from Armfield and is defined
by part number TEMPSENS-SAN-1.5PL.
The replacement sensor is simply screwed into the housing in place of the original
sensor and the plug connected to the appropriate socket at the rear of the cabinet
Replacing Temperature Sensor T4 (Hot Water Circuit)
Temperature sensor T4 is a thermocouple sensor.
If a replacement sensor is necessary this can be obtained from Armfield and is defined
by part number TEMPSENS-TYPEK.
The original sensor should be removed from the pipework above the hot water
circulator by unscrewing the compression fitting. The connecting lead and sensor
should then be fed through the cut out, in the corner of the main compartment floor
inside the cabinet, to allow the lead to be disconnected from the PCB.
The individual crimped wires should be removed from the Molex connector (Pins 13,
14, 15 & 16 of plug 10) on the PCB. To remove the crimped pins from the plug push
the wire towards the connector, depress the small tab on the side of the connector
using a miniature screwdriver then pull the wire to extract the crimped pin from the
plug.
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