Operation of Nor-Ray-Vac Ø5” System with NRVCP Control Panel
The Nor-Ray-Vac control panel contains a digital time switch, black bulb controller, fan starter & overload together with fan over-run timer all housed in an IP54 rated metal enclosure.
On the fascia, there is a panel live lamp (red), a system run lamp (amber) and a fan trip lamp (amber).
A three position mode switch operated with a key allows operation of OFF (frost protection only), ON (operates through the day temperature setting on the black bulb controller and over-rides the time switch) and AUTO (this operates through both the time switch and black bulb thermostat).
The controller will supply a voltage signal to both the fan and burner(s) when the following conditions are met:
a) power to the control panel is live / isolator in ON position
b) thermostat set point value are higher than room temperature
c) black bulb stat is operating and wired correctly back to the controller
d) mode switch is in either On or Auto position
e) clock is within time settings (if in AUTO position)
When all the above conditions are ok, a delay of some 30 seconds will occur prior to supply voltages out to both main fan and burners. The vacuum induced by the fan will cause the internal pressure switch within the end burner to make circuit allowing power to an onboard timer and after a preset delay, onto the electronic sequence controller to light the burner. A signal will simultaneously be sent to any inline burner(s) on that radiant branch where again allowing an onboard timer to delay a signal onto the electronic sequence controller to light the burner. The burner closest to the exhaust fan in each radiant branch will light first. Each subsequent burner will light at 25 second intervals until finally the end vent will light.
Once the time clock has switched/mode switch moved to off or the black bulb sensor is satisfied, power is lost to the burners and they will switch off. However the fan will continue to run for some 3 minutes to allow a cooling down period and exhaust of combustion products. If the system recalls for heat, the same sequence will start over again.
In split zone systems (where a singular fan is operating two or more zones), the operation for starting the Nor-Ray-Vac system is identical to above. However, where one zone is satisfied and another zone calls for heat, the pressure switch has to sense a positive pressure therefore the fan has to stop to allow the vacuum to dissipate. An electronic circuit within the control panel removes the supply voltage to all the burners in all zones as well as the fan for 30 seconds. The power is then reapplied and the starting sequence starts over again.
Please refer to separate documentation for the setting of the digital time switch (doc ref GB/AR/051/0601) and black bulb controllers (doc ref GB/CON/014/0312)