18
Concord CXS -
Installation & Servicing
19 COMMISSIONING AND TESTING
GENERAL
Check that all drain cocks are closed, that any stop valves
fitted to the flow and return pipes are open and that the
system has been filled and properly vented.
PURGING
Check that the electricity supply is switched OFF.
Remove the casing lower front panel.
Extinguish all naked lights and open all doors and windows.
DO NOT SMOKE. Check that the gas supply is turned ON at
the meter and open the main gas inlet cock. Loosen the
union and allow air to be purged from the gas line until gas is
smelled. Refer to BS 6891 or IGE-UP-1 for further details.
Retighten the union .
TESTING FOR GAS SOUNDNESS
Close the gas supply cock at the meter.
Remove the screw in the inlet pressure test point, Frames
20/21, and connect a gas pressure gauge to the test point.
Take particular care to ensure a gas-tight connection. Open
the gas supply cock at the meter and the appliance gas
cock; record the static pressure. Next, close the gas supply
cock at the meter. Wait for 1 minute for temperature
stabilisation then observe the pressure gauge over a period
of 2 minutes.
Any leaks must be cured.
Replace all pressure test point screws.
18 ZONES WITH SPRING-RETURN MOTORISED VALVES
IMPORTANT
Terminal L2 may control the appropriate
pump(s) directly, provided that the total
running or starting current does not exceed
6A (resistive or inductive): if this rating would
be exceeded then appropriate switchgear
must be used to control the pumps indirectly.
Three zones are illustrated but the principles
may be extended as required, provided the
above conditions are met. Only one relay is
required, irrespective of the number of zones.
Overrun
During overrun and dormant periods, Zone
Valve 1 is held open. This zone, therefore,
MUST satisfy the conditions in the foregoing
paragraphs and Graph 1.
Normal operation
During a call for heat on Zone 1 only, the
boiler energises via Zone 1 thermostat and
the normally closed contacts of the relay.
During a call for heat on other zone(s), the
relay will be energised by the auxiliary switch
on the zone valves. This provides power to
energise the boiler. If, in addition, Zone 1 now
calls for heat, its thermostat will open Zone 1
valve via the normally open contacts of the
relay.
When the clock period ends, Zone valve 1 will (stay) open via
normally closed relay contacts to achieve pump overrun.
Water circulation system - refer to page 5
INSTALLATION
INST
ALLA
TION
X2
