page no. 26 of 36
NVS Range Users, Installation & Servicing Instructions Doc Ref M102 issue 2.4 May 2018.
P2%
P3%
Drop Out
Volts
5
10
20
30
40
50
60
70
80
90
100
Hold-in Voltage
0
0.3
0.5
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
10
1.0
1.5
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
20
2.0
2.5
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
30
3.0
3.5
4.0
5.0
6.0
7.0
8.0
9.0
10.0
40
4.0
4.5
5.0
6.0
7.0
8.0
9.0
10.0
The MIB interfaces between a 0-10VDC control signal and
the modulating regulator. The following are applicable to
this application.
1. The setting of the slide switches 1 & 2 should both be to
OFF.
2. Potentiometer P1 (Default setting 100%)
The control current of the V7335A is controlled by P1,
varying between 50% and 100% of the input signal.
E.g.
-When P1 is set at 100% (fully clockwise) maximum power
(165mA @ 22VDC) is provided to the modulation coil with a
10VDC input control signal.
-When P1 is set at 50% (fully anticlockwise) maximum
power (165mA @ 22VDC) is provided to the modulation coil
with a 5VDC input control signal.
3. Potentiometer P2
Controls the minimum drop-out voltage between 0% and
40% E.g.
- When P2 is set at 0% the drop-out voltage with an input
control signal of 0-10V-DC is 0.3V-DC.
- When P2 is set at 40% the drop-out voltage with an input
control signal of 0-10V-DC is 4.0V-DC.
4. Potentiometer P3 (Default setting 100%)
Controls the maximum hold-in voltage. Its proportional
value is added to the P2 setting E.g.
- When P2 is set at 0% and P3 is set at 5%, the hold-in
voltage of the burner relay is adjustable between 5% and
100% of the input control signal. If the input control signal
is set at 0-10V-DC the hold-in voltage of the relay is 0.5V-
DC.
- When P2 is set at 40% and P3 is set at 5%, the hold-in
voltage of the burner relay is adjustable between 45% and
100% of the input control signal. If the input control signal
is set at 0-10V-DC the hold-in voltage of the relay is 4.5V-
DC.
The following table shows the relationship between P2 and
P3 settings.
2.6.6.2. Flame Current
1. To measure the flame current connect a multimeter
capable of measuring micro amps as shown in the
following diagram.
Flame Current Measurement
2. Minimum current reading is 0.5µA and normal value
should be 1.5µA or higher.
2.6.6.3. Air Heater Controls
1. Close the gas service tap and ensure that the gas valve
is heard to close within 1 second and that the lockout light
is illuminated. Note that the heater may attempt five re-
ignitions before going to lockout. Open the gas service tap
and reset the unit from lockout.
2. Check that the room thermostat and all automatic
controls are operating satisfactorily.
