VS8420C,M MILLIVOLT GAS VALVE
5
69-1304
Fig. 6. Installing ECO in window.
Fig. 7. Millivolt system wiring diagram with quick
drop-out thermocouple (VS8420D).
Pilot Gas Lighting Procedure
Lighting Standard Pilot (Without Piezo)
1.
Turn the knob counterclockwise
to the
PILOT position, push the knob down, and hold in
position. The pilot valve opens and allows gas to
flow to the pilot burner.
2.
Light the pilot burner while holding down the knob
until a strong flame is present (approximately 60
seconds).
3.
Release the knob. The shaft will move upward
and engage the safety valve lever that opens the
safety valve.
4.
Turn the knob counterclockwise
to the ON
position. On a call-for-heat, the main valve opens
and the main burner ignites.
Lighting Pilot with Piezo
1.
Turn the knob counterclockwise
to the
PILOT position, push the knob down, and hold in
position. The pilot valve opens and allows gas to
flow to the pilot burner.
2.
Push the plunger on the piezo until the pilot
burner is lit. Hold down the knob until a strong
flame is present (approximately 60 seconds).
3.
Release the knob. The shaft will move upward
and engage the safety valve lever that opens the
safety valve.
4.
Turn the knob counterclockwise
to the ON
position. On a call-for-heat, the main valve opens
and the main burner ignites.
Shut off Procedure
1.
To shut off the system, turn the knob clockwise to
the OFF position. This action closes the main gas
and safety valves; however, the power unit must
drop out before the lighting sequence can begin
again. The VS8420 drops out within 30 seconds.
2.
To relight the pilot light, follow the steps in the
Pilot Gas and Lighting Procedure section.
HI/LO Regulator
As you turn the HI/LO knob, the gas pressure changes.
1.
Turn the knob clockwise
toward the HI set-
ting to increase gas pressure.
2.
Turn the knob counterclockwise
toward
the LO setting to decrease gas pressure.
Minimum and maximum regulator settings vary for each
individual gas valve. Table 3 lists possible minimums
and maximums for gas valves. See gas valve label for
actual minimum and maximum ranges.
Table 3. HI/LO and Standard Regulator Pressures in mbar (in. wc).
ECO
CONNECTOR
M13322
M12678
HI/LO
REGULATOR
OFF
PILOT
O
N
PIEZO SPARKER
PILOT
ADJUSTMENT
SCREW
GAS
CONTROL
KNOB
Q313
THERMOPILE
HIGH LIMIT
CONTROL
MILLIVOLT
THERMOSTAT
ELECTRODE
TARGET
QUICK DROP-OUT
THERMOCOUPLE
VS8420 HI/LO MILLIVOLT GAS VALVE
Type of Gas
Hi/Lo Regulator Setting Ranges
Standard Regulator Setting
Ranges
Hi
Lo
Natural
7.5 to 9 (3.0 to 3.5)
3 to 6 (1.2 to 2.5)
(3.0 to 5.0)
LP
22.5 to 27.5 (9.0 to 11.0)
9 to 16 (3.7 to 6.5)
(8.0 to 12.0)