Gas valve 845 SIGMA (0.845.058)
Multifunctional gas supply control unit with two automatic shut-off valves, designed for use in boilers from brands such as Vaillant, Beretta, Immergas, Hermann, Demrad, Ariston, Baxi, E.C.A., Fondital, and Bosch. This gas valve ensures reliable and safe gas supply management and includes a pressure regulator and an electrically controlled power modulation device.
Technical specifications
| Parameter | Value |
| Connections | G 3/4 ISO 228 |
| Mounting position | Any |
| Gas type (families) | I, II, and III |
| Maximum inlet gas pressure | 60 mBar |
| Ambient temperature | -15…60°C |
| Electrical modulation | max — 17 V 165 mA |
| Manufacturer | Sit |
| Country of manufacture | Italy |
How to choose the right product
When selecting the gas valve 845 SIGMA, consider the following points:
- Compatibility with your boiler — check if this model is supported by your equipment.
- Connection type — ensure that the thread (internal or external) matches your existing equipment.
- Maximum inlet gas pressure and environmental working conditions — these should meet your boiler's requirements.
Possible causes of malfunction and prevention methods
Gas valve malfunctions can occur for several reasons:
- Seal wear: Regularly check and replace sealing elements to prevent gas leaks.
- Valve contamination: Perform periodic cleaning to avoid clogs.
- Incorrect pressure setting: Monitor gas pressure settings and adjust them as necessary.
Regular maintenance and inspection of the valve's condition will help prevent premature failure.
Difficulty of part replacement
Replacing the gas valve 845 SIGMA may require certain skills in working with heating equipment. It is recommended to follow these steps:
- Disconnect the boiler from electricity and gas.
- Drain water from the system if necessary.
- Remove the old valve by unscrewing the fasteners.
- Install the new valve, following the connection and adjustment order.
- Check all connections for tightness.
- Reconnect gas and electricity, and test the system operation.
The difficulty level of the replacement can be assessed as medium, so if you are unsure of your abilities, it is better to consult a specialist.
