Lambda system - real time combustion analysis

|The need

The gas valve regulation of condensing boilers at final test is made measuring the CO2 concentration in the fumes. The most common method is to suck up a fume sample from the chimney analysing it through infrared systems or through electrochemical cells. The answering time of these systems makes the regulation very long.

|The solution

Microplan experimented a system based on the use of a lambda probe similar to the ones used to control the combustion in motor vehicles. The measure of CO2 happens immediately. The system is completely electronic, it has not moving parts and it doesn't emit radiations of any type, so it is safe and strong.


  • Immediate: the lambda system has a typical answering time of 55 thousandths of a second.
  • Simple: the probe is small, light and it is simply fastened on the fumes pipe. Fumes suction and transportation systems are not required. Particular supporting or fastening frameworks are not needed. It is not necessary to modify the normal fumes path.
  • Low cost: compared to other fumes analysers the cost of a lambda system is very cheap.
  • Real: system like this are working on the production line of some Microplan's customers since the end of 2006.
  • Flexible: the device can work as a "stand alone" unit or it can be integrated in Microplan's test rigs.


Lambda system is a device to measure the values of CO2 in the exhausted fumes.


The lambda sensor, inserted in the chimney of the boiler or water heater under test, reads the value of Oxygen in the fumes and through a mathematic formula the value of CO2 is obtained. 


At the final test of boilers or water heaters, at the end of the production line.


  • Manufacturers of gas boilers
  • Manufacturers of gas water heaters






Where is the probe? 

in the chimney 

in the system 

in the system 

Is there a fumes aspiration system?




Where is the measure displayed?

meter display

monitor of a notebook or PC

monitor of the test bench

Which measure will be displayed? 

O2 wet

CO2 dry

CO2 dry

Where does the elaboration of the measures to calculate the values of CO2 d.a.f (dry air free) take place?no calculation of CO2in a program provided by Microplan to run on a support PCin the software of the test bench
Configuration of the systemlambda meter + probe + power supply (option)stand alone system featuring fumes aspiration, condensate drain, fumes temperature measurement system integrated in a Microplan test bench featuring fumes aspiration, condensate drain, fumes temperature measurement