baltur 67510010, Installation, Use And Maintenance Instruction Manual

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MODULATION OPERATION DESCRIPTION
When the burner is on at minimum flow rate, if the modulation probe
allows it (set to a temperature or pressure value higher than that in the
boiler) the air/gas regulation servomotor starts turning;
• in a clockwise direction the air flow increases;
• anticlockwise rotation: the air flow decreases.
thus gradually increasing gas supply and combustion air until the
maximum supply level set for the burner is reached.
The burner remains in the maximum flow position until the
temperature or pressure is high enough to trip the modulation probe,
which reverses the rotation of the air adjustment servomotor.
The inverse rotation and therefore the air and gas supply reduction
occurs shortly thereafter.
With this procedure, the modulation system attempts to balance the
amount of heat supplied to the boiler with respect to the amount the
boiler releases for use.
The modulation probe installed on the boiler measures any variation
requests and automatically adjusts fuel and combustion air supply, by
starting the air/gas regulation servomotor and increasing or reducing
rotation as necessary.
If the limit value (temperature or pressure) at which the stop device is
set (thermostat or pressure switch) is reached even with gas supply
at minimum level, the burner is shut down by the device.
When temperature or pressure returns below the shut-down device
tripping value, the burner is activated once again according to the
program described in the previous section.