EN2R-9053 0408R11-NE 10
DESCRIPTION OF SQUARE
 
TECHNOLOGY
SQUARE is the abbreviation of Self adaptive, Quality, User 
friendly, Adjustment free, Reliable, Environmental friendly.
SQUARE is able to control the load and burning process of a 
fully premix heating appliance under varying gas quality 
conditions. See fig. 8.
Features are :
• Gas adaptive control over the full natural gas band, with a 
modulation range of 1:5
• Electronic gas-air at a constant gas quality with a 
modulation range of 1:10
• Automatic chimney lenth compensation
SQUARE is based on the phenomena that the ionisation 
current is a measure of the gas quality at a specific range of 
the burner load in a fully premix burner.
After  calibration based on this phenomena, the burner can be 
influenced by means of a micro bridge flow sensor. see fig. 8.
If the gasvalve is closed, the micro bridge acts as an airflow 
meter in order to measure the chimney resistance.
Fig. 8. schematic SQUARE system
P
mix
u-bridge
CVI-M
FAN
GAS
AIR
P
air
=1013hPa
P