Thermona Therm 17 KD, Инструкция по установке и эксплуатации

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8. GAS FITTING SIT 848 SIGMA
SIT 848 SIGMA is a gas fitting with proportional regulation of air / gas. It is fitted with two solenoid valves for
blocking the gas penetration when the boiler is inactive. The regulation system functions on the basis of a feedback
signal on the gas pressure from the mixer. Apart from the lockable measuring extensions of the input, output and
mean gas pressures, there are also elements for setting the correct ratio between air and gas for the whole range of
the boiler output regulation.
1. Setting the regulation starting point
It is performed by a plastic screw in the boss of the regulation system of the
auxiliary diaphragm. To access the screw, first unscrew the protective brass
cap.
The value set by the screw is the mixture ratio at minimum boiler output (i.e.
minimum ventilator speed is already set). By tightening the screw, the
amount of gas in the mixture increases.
2. Setting the air / gas mixture ratio:
To do this, use the regulatory screw of the gas choke valve at the gas valve
outlet.
The value set by the screw is the mixture ratio at maximum boiler output (i.e. maximum ventilator speed is
already set). By tightening the screw, the amount of gas in the mixture decreases.
El. diagram showing the connection of the solenoid coils connectors:
The gas fitting contains two solenoid valves EV1 (gas input solenoid) and EV2
(regulation system solenoid). The coils in the connector of the connecting cable are
connected in a parallel fashion (i.e. they make contact simultaneously). Supply voltage
of the coils is 220V (A.C.).
Setting of the regulation starting point
Setting of the ratio air / gas
Measuring extension of
the output gas pressure
Gas output
Solenoid coils
Measuring extension of
the input gas pressure
Gas input
Air pressure signal input