Camus Hydronics DRW1000, Инструкция по установке и обслуживанию

Страница: 18 / 82

18
Low fire adjustment screw
Located under cap
(Turning clockwise increases gas flow)
3.4 AIR/GAS RATIO VALVE
The main gas valves supplying gas to the burner for models
2000 to 5000 on this appliance utilize a servo pressure regulator
providing a slow opening, fast closing safety shut off and an
air/gas ratio control valve for the gas combustion process. This
gas valve controls the pressure difference across the flow orifice
in the manifold supply line as a function of the pressure
difference across the combustion air supply to the burner. The
actuator maintains a constant air to gas ratio as the volume of
air changes based on the operation of the combustion air fan.
The valve is a 1:1 differential pressure air/gas ratio controller.
The valve generates the same pressure difference on the gas
side as it senses on the air side. Models 300 to 1800 utilize a
1:1 ratio dual seat negative pressure gas valve. Models 2000 –
3000 utilize a 1:1 air/gas ratio control valve and a safety solenoid
valve. Models 3500 – 5000 utilize a 1:1 air/gas ratio control and
regulating gas valve. The regulating gas valve performs the
functions of a pressure regulator, safety shutoff. Full closing of
the valve seat occurs in less than 0.8 seconds when the valve is
de-energized. Operation of the gas valve in combination with the
combustion air fan allows the burner input rate to vary from 20%
to 100% based on temperature demand. The inlet gas supply
pressure must be maintained within the specified minimum and
maximum pressures.
The air/gas ratio is preset at the factory and adjustment is not
usually required if gas supply pressure is maintained within the
specified range.
There are no serviceable parts on the dual seat negative
pressure air/gas ratio valve control.
A reduction of up to 30% is permitted in the inlet gas pressure
between light off and full fire conditions.
If the manifold differential pressure is to be measured, refer to
section 3.8 Checking Differential Air and Gas Pressures for
proper measurement.
Figure 8: DR300 – 400 1:1 Negative Pressure Air/Gas Ratio
Control Valve
Figure 9: DR500 – 1800 1:1 Negative Pressure Air Gas
Ratio Control Valve
Figure 10: DR2000 - 5000 1:1 Air/Gas Ratio Control Valve
Figure 11: DR3500 – 5000 SKP25 Regulating Gas Valve
Actuator & SSOV
3.5 DIFFERENTIAL AIR PRESSURE (DR2000 –
DR5000)
• The Dynaforce® 2000 – 5000 operates on the principle of
differential pressures. Operation of the fan generates a
signal which is matched on the gas side by the 1 to 1 air/gas
ratio control valve.
• The differential air pressure measurement is made between
the high and low pressure taps across the fan discharge
and the fan static discharge. All differential air pressures are
noted at full firing rate. There are two pressure taps at the
fan discharge and care must be taken to tee into the correct
line. The correct line may be identified by tracing it back to
the ratio control valve where the identification of the tapping
is stamped into the die cast actuator.
• The differential gas pressure measurement is made
between the high and low pressure taps across the in- line
metering gas orifice. Check this value to confirm that it
matches the differential air pressure while the appliance is
firing.
•
The controls on this appliance may fire the burner from 20%
up to 100 % of rated input.
•
Differential manifold gas pressure will be reduced as
burner input is reduced.
•
All reference gas pressure measurements must be made at
100% of rated burner input.
•
The differential gas manifold pressure is pre-set at the
factory through the ratio gas valve. Adjustment of manifold
pressure is not normally required for proper operation. It
may be necessary to adjust the low fire adjustment screw
located on the ratio control valve actuator in order to
achieve acceptable light off under soft start field conditions.
•
Always check settings posted on boiler test label.
Junction box for
power with
actuator position
indicator
High fire air/gas ratio adjustment
(use slotted screwdriver for
adjustment, counter-clockwise
increases CO
2
)
Low fire air/gas ratio adjustment
(use T-40 for adjustment,
clockwise increases CO
2
)
Lift top cover to access high fire
air/gas ratio adjustment
(use 3mm allen key for adjustment,
counter-clockwise increases CO
2
)
Low fire air/gas ratio adjustment
(use T-40 for adjustment,
clockwise increases CO
2
)
Gas Inlet
Actuator
Flange
Valve
Flange