Page 5 of 8
© Ventam Systems Ltd
Turn fan back on
– “Fans On” light should be lit on panel.
Repeat section 13.0 - Gas Proving part one
– “Gas On” panel light will come on.
Repeat step 14.1 for each interlocked fan
14.2 Gas Proving
“Gas On” light should still be lit.
Turn off all gas appliances.
Depress emergency stop button on the front of panel
– panel will indicate “Emergency Stop”
AND “Gas Off”.
Re-set the emergency stop button on the front of the panel, repeat step 13.0
– “Gas On”
panel light will come on.
Repeat step 14.2 for each additional emergency stop button fitted.
14.3 Fan pressure switch Adjustments
Fan pressure switches can be adjusted to trip the gas valve at the required air flow rate. As
a guide, the fans should trip the valve if the fans are reduced to below 50% of full speed, but
the ventilation system specifications for minimum flow rates must be followed.
Typically, if the speed controller minimum is to be set at 50% of max fan speed, then the Fan
pressure switch should be set to turn off the gas at 45%.
Allow a tolerance for the ventilation system to settle down and for the filters to become
partially blocked etc. If the speed controller is fitted with a minimum speed adjustment pot
(on the rear of the speed controller board), ALWAYS set this to set the minimum speed that
the fan will run and this will prevent user problems and premature fan failure.
A typical installation requires that the fresh air supply flow is at 85% of the extraction air flow,
and this can be allowed for in fan pressure switch adjustments to control minimum.
14.4 Using a current monitor to monitor the fan(s)
A current monitor may be used instead of a fan pressure switch to check that the fan is
operating. The current monitor must be set up to ensure that the gas turns off if the fan is
turned down too low or turned off. Adjust the current monitor so that this happens and test it.
As a guide, the fans should trip the valve if the fans are reduced to below 50% of full speed,
but the ventilation system specifications for minimum flow rates must be followed.
A typical installation requires that the fresh air supply flow is at 85% of the extraction air flow,
and this can be allowed for in current monitor adjustments to control minimum.
The current monitor should be installed so that the volt free current monitor contact is
CLOSED when the fan is running. This contact must be connected into panel terminals 1+2
OR 3+4.
14.3 Instruct site staff in correct system operation and instruct staff to clean filters
regularly .
Advise site staff NOT to decrease fan(s) speed or gas valve will NOTOPERATE!!!!
Ask the user to start the fans, increase the fan speed etc to ensure the user is
familiar with and understands system operation and that the system is installed for
their safety.