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Novar Controls (Sequence of Operation)
Economizer Set-up
The economizer function on a Novar-controlled unit is controlled more directly than in normal
operation. The economizer is wired with additional inputs from the Novar controller to provide this
control:
Manual Enthalpy Override
The economizer control actuator (ECA) is configured for Novar operation by placing a 100K
resistor across the normally unused outdoor air temp input on the ECA. This signals the
economizer to enter Manual Enthalpy Override which enables economizer cooling operation at all
times regardless of outdoor or indoor conditions.
Damper Relay
A relay output on the Novar controller is that signals a relay placed in-line with the mixed air
temperature sensor. It is used to interrupt the mixed air sensor signal to the ECA indicating when
to modulate for economizing or to go to minimum position. If an open is detected on the mixed
air temperature input the ECA will hold the damper at minimum position.
Nightmode Damper Relay
A relay on the Novar controller is connected across the remote minimum position potentiometer
inputs (P and P1) on the ECA. When the relay contacts are closed for Nightmode operation the ECA
uses a default damper minimum position of 0%. When they are not closed it uses the standard
minimum position adjustment on the ECA as default.
[Gas/electric] Heating
The Novar controller uses its zone temperature input and setpoint input to determine when to
initiate requests for compressors or heat. Calls for heating are interpreted by the Reliatel controller
as thermostat requests. When the zone temperature is sufficiently lower than the setpoint the
Novar will energize its Heat 1 (W1) output to turn the first stage of heat on. It will also close the
contacts on its Fan (G) output to call for the Supply Fan to turn on.
The first stage of [Gas/Electric] heat will energize. If additional heating capacity is required above
that provided by the first stage the second stage of [Gas/Electric] will be activated by energizing
the Heat 2 (W2) output.
Once the zone temperature rises above the setpoint sufficiently the heat and fan outputs on the
Novar controller will be deactivated and the RTRM will respond appropriately and deactivate its
respective outputs.
On Gas Heat units the Supply Fan will remain on for a period of 90 seconds after heat is deactivated
for free heating and heat exchanger cool down.
Novar Controls Checkout/Troubleshooting Procedure
General
The Novar Electronic Thermostat Module (ETM) includes an installation manual that describes the
basic connections and checkout of the Novar controller. This manual should be consulted during
installation, checkout, or troubleshooting.
If problems are encountered with unit operation after consulting the Novar ETM installation
manual, the following checkout procedures may help to determine and isolate the cause of the
problem.
Checkout Procedure
1. If the Novar controller is connected to the BAS network, check for any failure messages related
to the controller in question. Take appropriate actions if messages exist.
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