9
EN2R-9053 0408R11-NE
DESCRIPTION OF LOCON
LOCON means Load Control.
LOCON is able to measure and control the load of a gas fired
heating appliance.
LOCON is suitable for atmospheric (with or without fan)
modulating boilers.
Features are:
No or minimum adjustments of VK4105G2000 valve at the
production of the combiboiler.
Improvement of the DHW temperature control performance.
Easy swap from LPG to natural gas
LOCON is based on the phenomena that the ionisation flame
current in an atmospheric boiler is almost linear with burner
load. (see fig. 7)
Using this property the critical minimum pressure and ignition
pressure adjustment can be avoided.
If a throttle is used for maximum pressure regulation no
adjustment is needed.
Only injectors have to be changed if LPG is needed.
( see fig. 6.for the control flow diagram )
Fig. 6. LOCON control flow diagram
Fig. 7. Ionisation flame current versus the boiler load
REMARK: Electrode postition and choice is important.
In cooperation with Polidoro, Honeywell has made
a standard solution.
New applications require Honeywell approval.
PI control
Valve current control
temp.
setpoint
ionisation current
+
Burner
-
LOCON loop
Heat exchanger
NTC temperature sensor information
+
-
temp.
control
B
min
B
ign
B
max
I
flame-max
P
0 max
I
flame (P0) ign
I
flame (P0) max
Boilerload
I
flame
(P
0
)
throttle-adjustment
at P
i-nom