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Installation Requirements - Page 9
1.6
Installation to an Existing Central Heating
System
•
The appliance is designed to operate on a sealed
system only, therefore if the existing system is of the
open type it will have to be modified to comply with BS
6798.
•
Before installing a new combination boiler to an existing
system flush out the old system with a recommended
descaling/flushing agent at least twice, see Inhibitors on
Page 12.
•
Also check pipework and renew any corroded pipework
or fittings. Valve glands must be re-packed or replaced
wherever necessary and any defective controls
replaced.
1.7
Hard Water Areas
•
If the area of installation is recognised as a hard water
area, (above 200 p.p.m.) it is essential that a suitable
water treatment device of an electronic, magnetic or
galvanic type be installed in the mains water supply.
Consult with the Local Water Company.
1.8
System Requirements
Before installing the boiler onto the system read the
section on Page 12 about Inhibitors.
Domestic Hot Water
•
The domestic hot water system must be in accordance
with the relevant recommendations of BS 5546. Copper
tubing to BS 2871:1 is recommended for water carrying
pipework and MUST be used for pipework carrying
potable water. All capillary joints in the D.H.W pipework
must be joined with a lead free solder.
Central Heating
•
This appliance has been specifically designed for
sealed systems only. Therefore the central heating
system should be in accordance with the relevant
recommendations given in BS 6798 and also, smallbore
and microbore systems BS 5449 Part 1.
•
For correct operation the boilers require a by-pass.
A valved by-pass should be fitted and the flow reduced
to balance the system correctly. The length of the by-
pass pipework is not important.
Note: If the by-pass flow is reduced too much this will
cause the appliances to overheat and go to lockout.
•
The installation should be designed to work with flow
temperatures of up to 90 °C. All components of the
system must be suitable for a maximum pressure of 3
bar (45 psi) and a temperature of 110 °C.
•
The following components are incorporated within the
appliance.
a. Circulating pump.
b. Diverter valve.
c.
Pressure Relief valve with a non-adjustable pre-set
lift pressure of 3 bar (45 psi).
d. Pressure gauge covering the range 0-4 bar (0-60
psi).
e. 10 litre expansion vessel with initial charge pressure
of 1.0 bar (14 psi).
f.
Domestic Hot Water flow switch.
•
The central heating output from the boiler can easily be
downrated if a lower temperature drop across the
system is prefered.
•
Ancillary pipework, not forming part of the useful heating
surface, should be lagged to prevent heat loss and any
possible freezing, particularly where pipes run through
roof spaces and ventilated under-floor spaces.
•
If the capacity of the central heating system should
exceed 100 litres, an additional vessel should be
installed on the return to the combination boiler from the
heating system. Guidance on vessel sizing is given in
Table 2 - Page 10.
•
To allow the maximum central heating expansion
capacity in the boiler the pre-charge pressure in the
central heating expansion vessel must be marginally
greater than the initial (cold) system pressure at the
appliance (as shown on the appliance pressure gauge).
•
Draining taps should be at least 1/2 in BSP nominal size
and be in accordance with BS 2879.
•
External Controls
To obtain economical use of the appliance it is advisable
to fit external controls. The controls can take the form
of:-
a. Time clock (two internal options are available)
b. Room thermostat
c.
Thermostatic radiator valves (TRV's)
c.
Zone valves
A combination of these controls will produce economical
and effective use of the heat generated by the boiler. It
is advisable to control the temperature of the main living
area with a room thermostat and other areas by TRV's.
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