Glow-worm 18-30sxi Range - Manual (Page 15)

15 0020008155A
4 Heating System
Table 3. Flow Rate
MODEL MINIMUM FLOW RATE
18sxi 774 litres/hr.
30sxi 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 read-out on the controls fascia indicates the system
pressure when there is no 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 change pressure of 0.5bar.
NOTE: The expansion vessel volume depends on the total
water system volume and the initial system design pressure. To
check if an additional expansion vessel is required, an accurate
calculation of vessel size is 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".
4.3 Flow Rate
The flow rate through the boiler must not be allowed to fall below
that given in Table 3.
The system can be fitted with a lockable balancing valve if
necessary in the main flow or return pipes shown as valve “A”
in diagram 4.1.
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
Provision for filling the system at low level must be made, see
diagram 4.2. There must be no permanent connection to the
mains water supply, even through a non-return valve.
NOTE: It is important that fittings used for connection to potable
water comply with the water undertakings requirements.
BOILER
DRAIN
POINT
'A'
FLOW CONTROL
VALVE
HEATING
CIRCUIT
RETURN
ADDITIONAL
EXPANSION
VESSEL
(if required)
* BYPASS
(if required)
Diagram 4.1
10157
* Refer to section 11.6