Service Manual

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4.7 Gas Valve
It is possible to control gas flow to the burner by the modulating gas valve (MV) in addition to the
control unit. The gas valve is composed of an additional solenoid identified as safety valve (SV1)
releasing the modulated gas to and from the solenoid gas valve.
Safety Solenoid Valve
The safety valve (SV) is the first safety element that releases gas to the burner. The second safety
level elements are the solenoid valves in the gas manifold of the burner. They release gas to the
first, second, and third burner segments, respectively, acting as safety and segmentation valves.
Figure 21 – Gas Valve View
Modulating Valve
Mechanical modulated valve
The gas flow (thermal load) is automatically modulated to ensure the correct outlet water
temperature, even under water flow or inlet temperature variations.
To disassemble the gas valve, the necessary steps are the following:
1. Release the nut on the gas tube.
2. Remove the 4 screws on the buttons of the appliance.
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