Camus Hydronics Valiant-FT II Series, Installation And Service Manual

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10% to 100%. These utilize a 1:1 ratio dual seat negative
pressure gas valve. The gas valve adjusts fuel supply
according to negative pressure generated by the
combustion fan. The valve is dual seat and serves as a
safety shut-off. The inlet gas supply pressure must be
maintained within the specified minimum and maximum
pressures (a reduction of up to 30% is permitted in the inlet
gas pressure between light-off and full fire conditions).
Figure 20: Zero Governor Gas Valve (VA0400)
Figure 21: Zero Governor Gas Valve (VA0500)
Figure 22: Zero Governor Gas Valve (VA0600-VA0850)
3.2 GAS PRESSURE SWITCHES (Optional)
Gas pressure switches prevent the burner from being
activated if pressure is outside certain ranges. Each switch
is a physical manual reset device, requiring physical
depression of the reset button if it is not closed prior to
burner start or during burner operation.
3.2.1 Low Gas Pressure
A low gas pressure switch is standard equipment and
monitors the minimum incoming gas supply pressure
supplied to the gas train. If gas pressure upstream of the
valve(s) falls below the minimum setting of the pressure
switch, the switch will open and the appliance will shut
down. An open gas pressure switch alarm will be shown on
the display.
3.2.2 High Gas Pressure
High gas pressure switches may be ordered to comply with
CSD-1 code. These will either be integrated into the gas
train. If gas pressure downstream of the gas valve(s)
exceeds the maximum setting of the pressure switch, the
switch will open, and the appliance will shut down.
3.3 AIR PRESSURE SWITCHES
3.3.1 Blocked Flue Switch
All models use a normally closed blocked flue switch to shut
down the appliance under conditions of blockage of the air
intake or the flue outlet.
3.3.2 Low Air Switch
The low air switch is closed by operation of the combustion
air blower, to confirm that there is air flow present. This
switch is adjustable but typically does not need to be altered
from factory settings. Once this switch is closed the unit
initiates the pre-purge counter. If this switch opens during
operation the unit will lock-out.
3.4 COMBUSTION AIR BLOWER
Figure 23: Valiant FT Series II Combustion Air Fan
The Valiant FT Series II uses a modulating air fan to provide
combustible air/gas mix to the burner and push the products
of combustion through the heat exchanger and venting
system. The fan assembly consists of a sealed housing and
fan wheel constructed from spark resistant cast aluminum.
The fan is operated by a fully enclosed 120 VAC, Single-
Phase EC/DC electric motor. The fan housing and motor
assembly is fully sealed and SHOULD NOT be field
serviced.