Glow-worm Ultracom2 cxi - Manual (Page 13)

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INSTALLATION
7.2.2 Heating circuit design
6
7
9
10
11 1
2
3 4
5
Key
1 Drain point
2 External bypass (if required)
3 Domestic hot water out
4 Domestic cold water supply in
5 boiler
6 filling loop - to be unlocked and disconnected after use.
7 Double check valve assembly
8 Additional expansion vessel (if required)
9 Heating return circuit
10 Heating flow circuit
General
This boiler is designed for use as part of a sealed water central
heating system with fully pumped circulation. The pump,
expansion vessel and associated safety devices are all fitted
within the boiler.
Safety valve
The safety valve is an integral part of the boiler and it cannot
be adjusted. The pipe from the safety discharge valve must
discharge safely in accordance with standards.
Expansion vessel
The boiler has an integral expansion vessel with a capacity of 8
litres (1.76 gallons), with a charge pressure of 0.75bar.
i
The heating system volume should be calculated to
ensure that the expansion vessel is suitable, it may
be necessary to add an additional vessel.
- In GB, Guidance on vessel sizing is also given in the current
issue of BS5449 and BS7074 Part 1.
- In IE, current edition of I.S.813 “Domestic Gas Installations”.
Bypass
The boiler is fitted with an automatic bypass which can be
adjusted to suit your system requirements.
• Ensure that under no circumstances does the flow rate drop
below the figure specified, refer to chapter "Technical data".
Filling the sealed system
i
The water pressure at the boiler must be at least
1.2bar to operate the filling loop. If the pressure
is less than 1.2bar an external filling loop must be
fitted. If this pressure is not available contact the
local water authority.
Suitable external filling systems are shown diagrammatically,
see diagram below.
1
2
3
3
2
1
7
9
8
5
6
5
4
7
Key
1 Heating flow circuit
2 Heating return circuit
3 boiler
4 Double check valve assembly
5 Domestic cold water supply in
6 Temporary filling loop (remove immediately after filling)
7 Drain point
8 back flow prevention device
9 Tundish
The system should be pressurised to 0.8bar, indicated on the
digital display with no heating demand.
Drain points
Drain taps must be provided at all low points of the system,
which will allow the entire system to be drained.
Drain taps shall be to the current issue of BS2879.