Reznor, Photon, Installation Manual, EN 2021-04, D301310 Iss 0 Page No 23 of 52
C
Model 120
To adjust the throttle use a flat blade screwdriver
to remove the large round cover on top of the
gas valve. Using a 3mm hex key on the screw
located on the venturi, rotate counter clockwise
to increase %CO2. Rotate clockwise to decrease
%CO2.
To adjust the offset, use a T40 torx key to
remove the protection cap on the gas valve.
Rotate counter clockwise to decrease pressure /
%CO2 and rotate clockwise to increase pressure
/ %CO2. Refit cap after adjustment. There is no
pressure outlet measurement point on this gas
valve.
1 - Offset adjustment
2 - Inlet pressure measuring point
3 - CO2 adjustment point (throttle)
Figure 8 Gas valve adjustment model 120
Gas conversion
PHOTON unit heaters are designed to operate
on natural gas types G20, G25 and G25.3.To
modify for use on an alternative listed gas type,
follow the commissioning guide and refer to the
Combustion Data table for approximate throttle
turns from G20 setup.
The data label needs to be updated after
conversion. Using permanent ink place an 'X'
in the box above the relevant gas type column
to indicate the new gas setting. Obscure any
previous indication.
Upon completion of conversion recommission
the heater. Refer to the commissioning section
for more details.
Commissioning checks
Commissioning requires the use of a CO/CO2
flue gas analyser with an inaccuracy < 0.1% and
two pressure gauges.
For measuring gas pressure a resolution of 0.1
mbar or better is recommended.
For measuring offset pressure a low range
gauge with a resolution of 1 Pa or better is
required.
Read section on air-gas ratio control
adjustment before proceeding.
During commissioning the appliance %CO2, CO
ppm and flue gas temperature values should be
compared to those shown in the Combustion
Data Table.
1. Slacken screw in gas valve inlet pressure test
point and attach gas pressure gauge.
2. Start the appliance following the start up
procedure.
3. Ensure the thermostat is set to call for
maximum heat (10V). For optimal appliance
control during commissioning the 0-10VDC
thermostat inputs can be substituted with
a manually adjustable 0-10VDC generator
wired into the burner terminals 66 & 64 (see
wiring diagram).
4. Check gas supply pressure against the values
on the data plate. If gas supply pressure is
too low, shut-down the unit and correct.
5. Put CO/CO2 analyser probe into flue.
Observe the CO/CO2 readings and adjust
throttle screw until nominal high fire
%CO2 value is ac/- 0.1%CO2 (see
Combustion Data for details). If the venturi
has been replaced it can be approximately
set by fully closing and then adjusting the
throttle a set number of turns as indicated in
the combustion data table.
1
2
3
