Reznor, RHC21 4000 Installation EN May 2021 D301334 Issue 0 Page No 27 of 56
Commissioning procedure
Read section on air-gas ratio control
adjustment before proceeding.
During commissioning the appliance %CO
2
, CO
ppm and flue gas temperature values should be
compared to those shown in the Combustion
Data
Slacken screw in gas valve inlet pressure test
point and attach gas pressure gauge.
1. Start the appliance following the start up
procedure.
2. 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).
3. Check gas supply pressure against the values
on the data plate. If gas supply pressure is
too low, shut-down the unit and correct.
4. Put CO/CO
2
analyser probe into flue.
Observe the CO/CO
2
readings and adjust
throttle screw until nominal high fire
%CO
2
value is ac/- 0.1%CO
2
(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.
If the chamber insulation has been replaced the
organic binders will burn off during the first
few minutes of operation. This will result in a
temporary increase in CO and CO
2
readings.
5. Keep appliance running at full rate until
completely stabilised and recheck %CO
2
.
If necessary make further adjustments to
throttle before proceeding.
6. Slacken screw in gas valve outlet pressure
test point and attach low range pressure
gauge. Note, offset is a vacuum reading.
Gas pressure test points for all RHC21 4000
models except RHC21 4100-12
Gas pressure test points for model
RHC21 4100-12
To set low fire adjust thermostat to call for
minimum heat (1V):-
• Adjust offset screw to obtain nominal offset
pr/- 5 Pa (See Combustion Data for
details).
• Observe the CO/CO
2
readings and adjust
offset screw if needed to obtain nominal low
fire %CO
2
(+/-0.1%CO
2
).
• Return heater to high fire (10V) and recheck
high fire %CO
2
value. If necessary make any
final adjustments to the throttle.
• Disconnect pressure gauges and tighten
screws in gas valve test points.
• Remove heat demand and allow heater to
shut-down.
• Reconnect thermostat connections if
bypassed for commissioning.
Inlet test
point
Outlet
test point
Inlet test
point
Outlet
test point
