16
0020008154A
Table 3. Flow Rate
MODEL MINIMUM FLOW RATE
24 cxi 774 litres/hr.
30 cxi 1032 litres/hr.
38 cxi 1289 litres/hr.
This is equal to 20
O
C differential at maximum heat input.
4.1 General
The boiler is for use only with sealed central heating systems.
The safety valve is an integral part of the boiler and it cannot be
adjusted.
The digital readout on the controls fascia indicates the system
pressure when there is no central heating demand.
The circulation pump is integral with the boiler.
4.2 Expansion Vessel
The boiler has an integral expansion vessel with a capacity of
8 litres (1.76 gallons), with a charge pressure of 0.5bar.
NOTE: The expansion vessel volume depends on the total
water system volume and the initial system design pressure.
Guidance on vessel sizing is also given in the current issue of
BS5449 and BS7074 Part 1, for IE refer to the current edition of
I.S.813 "Domestic Gas Installations".
4 Heating System
Diagram 4.1
9168
* Refer to section 11.6
Diagram 4.2
11474
FILLING LOOP
TAP
FILLING LOOP TAP
EXTENSION
REDUCED
PRESSURE
ZONE VALVE
4.3 Flow Rate
If it is necessary to alter the flow rate, the system can be fitted
with a lockable balancing valve in the main flow or return pipes
shown as valve "A" in diagram 4.1. The flow rate through the
boiler must not be allowed to fall below that given in table 3.
4.4 Bypass
The boiler is fitted with an adjustable automatic bypass. Ensure
that under no circumstances does the flow rate drop below the
figure specified, refer to table 3 and section 11.6.
The installation of the boiler must comply with the requirements
of the current issue of BS6798, in Ireland, refer also to the
current edition of I.S.813 "Domestic Gas Installations".
In GB it is necessary to comply with the Water Supply (Water
Fittings) Regulations 1999 (for Scotland, the Water Byelaws
2000, Scotland).
To comply with the Water regulations your attention is drawn to:
The Water Regulations guide published by the Water Regulations
Advisory Service (WRAS) gives full details of the requirements.
In IE the requirements given in the current edition of I.S.813
"Domestic Gas Installations" and the current Building Regulations
must be followed.
4.5 Filling the Sealed System
NOTE: The water pressure at the boiler must be at least 1.2bar
to enable filling the boiler to a minimum pressure. If not
pressurisation must be carried out by an alternative filling loop.
The boiler has a built in filling device, see diagram 4.2. A push-
on extension is supplied in the loose items pack to ease access
to the filling device tap.
This filling device is designed to enable the re-pressurisation of
the system in the event of loss of pressure. It is not intended to
be used to completely fill the system. If so used, it may take a
long time to fill the system.
To fill the system quickly provision should be made to include a
proprietry filling loop external to the boiler.
Suitable external filling systems are shown diagramatically, see
diagram 4.3. The system should be pressurized to 1 bar,
indicated on the digital display with no heating demand.
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