Glow-worm Flexicom hx - Manual (Page 14)

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INSTALLATION
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5 Water Systems - General
5.1 General
This boiler is designed to provide central heating from a fully
pumped open vented or sealed water system and domestic hot
water using a fully indirect vented or unvented cylinder.
5.2 Draining Points
Draining taps must be provided at all low points of the system,
which will allow the entire system to be drained.
Draining taps shall be to the current issue of BS2879.
5.3 Pump
The pump should be fi tted on the fl ow pipe from the boiler and
have isolating valves each side.
A variable duty pump should be set to give a temperature
difference of no greater than 20
o C between the fl ow and return,
with the thermostat set at “MAX”, which is about 80 o C, to give a
fl ow rate as given in the table.
See chart for pressure loss of the boiler, diagram 5.1.
Diagram 5.1
14506
DRAIN
POINT
High resistance microbore systems may require a higher duty
pump.
5.4 Flow Rate
If it is necessary to alter the fl ow rate, the system can be fi tted
with a lockable balancing valve in the main fl ow or return pipes
shown in diagram 5.4. The fl ow rate through the boiler must not
be allowed to fall below that given in diagram 5.2.
0 5 10 15 20 25 30
Flow Rate (litres/min)
24kW
30kW
Pressure Loss (metres)
15kW
35kW
Diagram 5.2
14401
5.5 Bypass
A system bypass is required and should be fi tted at least 1.5
metres away from the boiler, refer to the current issue of the
central heating system specifi cations (CHeSS).
5.6 Water Treatment
5.6.1 General
The Glow-worm Flexicom range of boilers have an
Aluminium alloy heat exchanger. Water treatment products
used in the system should be suitable for use with
Aluminium.
Existing system - It is ESSENTIAL that prior to installing the
new boiler the system is thoroughly fl ushed.
New system - For optimum performance after installation, the
boiler and its associated central heating system should also be
fl ushed.
For long-term corrosion protection, after fl ushing, an inhibitor
should be used, refer to the current issue of BS 5449 and BS
7593 on the use of inhibitors in central heating systems.
Debris left in the system can damage the boiler,
reduce effi ciency and also lead to system
corrosion and generation of fl ammable gas.
Failure to comply with the guidelines for the
use of water treatment with the appliance will
invalidate the appliance warranty.
The pH value of the system water must be
between 6.5 and 8.5 or the appliance guarantee
will be invalidated.
Before fl ushing the system
• Ensure that the system and pipe work is in good working
order.