20/69
Siemens Building Technologies
Electronic Air / Fuel Ratio Control System
CC1P7873.1en
HVAC Products
5 Description of functions
15.10.2002
5.6 Selection of type of fuel
The RVW26… is designed for use with single- or dual-fuel burners.
The load / position curves and a number of other parameters (such as ignition load,
etc.) depend on the type of fuel and must be changed when the type of fuel is changed.
This change is accomplished with the 2 fuel selection inputs «F1» and «F2».
Changeover of the type of fuel immediately activates the parameters of the fuel se-
lected.
Signals at terminals «F1» and «F2»:
Signal at terminal «F1»
Signal at terminal
«F2»
Meaning
AC 0 V
AC 230 V
Fuel 2
is selected, that is, the curves and
parameters for fuel 2 are active
AC 230 V
AC 230 V
Inadmissible state
; lockout occurs after
about 4 seconds
AC 230 V
AC 0 V
Fuel 1
is selected, that is, the curves and
parameters for fuel 1 are active
AC 0 V
AC 0 V
This state is tolerated in phases 8, 9 and 0.
In all other phases, this is an inadmissi-
ble state;
lockout occurs after about 4 sec-
onds
(AC 230 V corresponds to AC 195...265 V; AC 0 V corresponds to AC 0...50 V)
Note:
Fuel changeover with the handheld terminal AZW20.20 is not possible!
The type of fuel is
always selected externally
via terminals «F1» and «F2».
For this reason, prior to setting the fuel-related parameters (curves, ignition load, etc.),
the required type of fuel must first be selected externally.
