Page No 28 of 56 Reznor, RHC21 4000 Installation EN May 2021 D301334 Issue 0
5.10 Commissioning - hand over
Upon full and satisfactory completion of
commissioning, a record of commissioning
information should be left with the person
responsible for the heater. The commissioning
engineer must ensure that the user is familiar
with the safe and efficient use of the heater,
detailing the function of all controls and main
components.
The user should be made aware of the following
in particular: -
(i) Lighting, shutdown, and operational
information.
(ii) Safety features, data plate, and labelling.
(iii) The requirement for regular inspection
- especially if the heater is within a more
demanding environment - and the need for
regular servicing carried out by a suitably
qualified person.
A commissioning record sheet is provided at the
end of this manual.
5.11 Operation
The appliance requires a 0-10VDC signal to
control the burner. A value > 1.0VDC will
indicate a heat demand and the combustion fan
will start the pre-purge.
Before an ignition attempt the combustion
fan slows to ignition speed. When the ignition
speed has been reached the burner will attempt
ignition.
If ignition is unsuccessful there will be another
purge followed by ignition. The total number of
ignition attempts before lockout is 3.
The spark electrode stays energised throughout
the ignition attempt, even if the flame has been
established.
Once the flame has been sensed the burner
will run at the ignition speed for a few seconds
to allow the flame to stabilise. Following flame
stabilisation the fan speed will increase to high
fire to allow the heat exchanger to warm up
quickly.
After a short delay the air movement fan will
start. Once warm up has completed the burner
is released to the control of the 0-10VDC
thermostat and will modulate to the requested
heat demand.
The burner will begin to modulate before the
set temperature has been reached. At this point
the burner rate will adjust according to the heat
demand from the thermostat.
When set point temperature is reached the
burner will turn off and the appliance will post-
purge to dissipate any residual heat.
If, for any reason, the burner flame is
extinguished during a run cycle, an automatic
attempt at re-ignition will take place. If after
three ignition attempts the burner does not
relight, safety shut down and lockout will occur.
Manual intervention to reset will be necessary to
put the unit back into service.
In the event of overheating for any reason,
overheat controls operate to switch off the
burner.
The limit control LC3, which operates at a
higher temperature setting, switches off the
burner to a lockout condition requiring a
thorough check of the heater and a manual
reset via the LC3 limit control body followed
by the lockout reset switch. A cooling time of
about 3 minutes is necessary before resetting.
The appliance is fitted with an LED status light.
This can be used to determine the current
status of the appliance and help to diagnose
fault conditions. See Figure 9 : LED Status table
overleaf for more information.
