Glow-worm Xtramax - Manual (Page 11)

11
4000116705-2
3.1 Bypass
• The boiler is fitted with an adjustable automatic bypass.
Ensure that under no circumstances does the flow rate drop
below the figure specified, see diagram 3.1.
• A bypass is not required on the central heating circuit unless
the system controls could allow the boiler to operate when there
is no flow.
• Where a bypass has to be fitted, the bypass must be placed
at least 1.5 metres away from the appliance, see diagram 9.2.
3.2 Filling the system
• Provision for filling the system must be made, the methods are
shown in diagram 3.2. 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.
TEMPORARY
CONNECTION
HOSE
UNION
HOSE
UNION
SUPPLY
PIPE
CONTROL
VALVE
CONTROL
VALVE
DOUBLE
CHECK
VALVE
BOILER
RETURN FLOW
HEATING
CIRCUIT
DRAIN
POINT
Method 1
SUPPLY
PIPE
AIR GAP
TUNDISH
CONTROL
VALVE
CONTROL
VALVE
TYPE CA BACKFLOW
PREVENTION DEVICE
BOILER
RETURN FLOW
HEATING
CIRCUIT
DRAIN
POINT
Method 2 Diagram 3.2
11594
3 Heating System Design
• The piping system shall be routed so as to avoid any air
pockets and facilitate permanent venting of the installation.
Bleed fittings must be provided at every high point of the system
and on all radiators.
• The total volume of water permitted for the heating system
depends, amongst other things, on the static head in the cold
condition. The expansion vessel on the boiler is pressurised at
0,5 bar (corresponding to a static head of 5 m w.g.) and allows
a maximum system volume of 160 litres for an average
temperature of 75°C and a maximum service pressure of 3 bar.
This pressure setting can be modified at commissioning stage
if the static head differs. An additional expansion vessel can be
fitted to the system if required, see diagram 9.2.
• Provision shall be made for a drain valve at the lowest point of
the system.
• Where thermostatic radiator valves are fitted, not all radiators
must be fitted with this type of valve, and in particular, where a
room thermostat is installed.
• In the case of an existing installation, it is ESSENTIAL that the
system is thoroughly flushed prior to installing the new boiler,
using a proprietary product such as Fernox or Sentinel. Contact
the product manufacturers for specific details.