Glow-worm 23c - Manual (Page 10)

10 2000225000B
3 Heating System Design
• The 23c is compatible with any type of installation.
• Heating surfaces may consist of radiators, convectors or fan
assisted convectors.
• Pipe sectional areas shall be determined in accordance with
normal practices, using the output/pressure curve
(diagram 1.1). The distribution system shall be calculated in
accordance with the output requirements of the actual system,
not the maximum output of the boiler. However, provision shall
be made to ensure sufficient flow so that the temperature
difference between the flow and return pipes be less than or
equal to 20°C. The minimum flow is 500 l/h.
• 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 and allows a maximum system volume of 110 litres for
4 Domestic Hot Water System Design
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 8.2.
• 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 the
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 Fenox or Sentinel. Contact
the product manufacturers for specific details.
3.1 Filling the system
A filling device is fitted to the boiler to initially fill the system and
replace water lost during servicing, see the relevant parts of
diagram 2 controls and lighting and diagram 8.2.
• Copper tubing or plastic Hep
2
0 may be used for the domestic
hot water system. Unnecessary pressure losses should be
avoided.
• The flow restrictor must be fitted limiting the flow through the
boiler to a maximum of 10 l/min.
• The boiler will operate with a minimum supply pressure of 0,6
bar, but under reduced flow rate.
Best operating comfort will be obtained from a supply pressure
of 1 bar.
4.1 Hard Water Areas
In areas where the water is 'hard', more than 200mg/litre, it is
recommended that a proprietary scale reducer is fitted in the
cold water supply to the boiler.