modulating gas burner

Hello,
Does anyone knows how the hardware (and software) of a regulator to start modulating the gasburner of central heating works.
I mean modulating on the boilers own thermostate (set on 60C).
The boiler measuring points are suction and return temperature.
The signal to start modulating go to the boilerfan speedregulator with on his turn regulate the gasvalve and this mixture goes through a venturi ad the premix burner.
Thanks in advance
Albert
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What do you want to know? You have described it correctly. The fan speed is set according to the burner power required. The venturi generates a negative pressure according to the air flow generated by the fan. This pressure is passed to the gas valve and used to regulate the flow of gas.
There are other schemes too which provide a proportional voltage to a specially designed gas valve, but I'm not familiar with how that works.
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Andrew Gabriel
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I want to know how the controller works, the electronic circuit, which building blocks ( IC etc) are possibly used to make it work. The control unit used in my cv boiler which control a lot more is from Honeywell (MCBA 1461 V3.1) but the agent in my country won't give any information on it.
Albert

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