SECTION 10: COMMISSIONING
Figure 17: Dungs Gas Valve
10.4 Gas Valves
Dungs Combination Gas Valve
All model 015 - 030
The main gas is released at the second stage, and the combination main gas valve block contains a main burner pressure regulator and two safety shut- off valves, for all gas types. See Page 37, Figure 17. For high/low or modulating burners, the Dungs gas valve has extra features because it is an air/gas ratio control valve. Please refer to the manufacturer’s instructions for setting the controls.
10.4.1 Start Gas Valves
appliances and need no further adjustment. When replacing a gas valve, ensure that this device is set in the fully open position by releasing the locking screw and turning the "V MAX" fully counter- clockwise towards the "+" and then retightening the locking screw.
10.4.4 Rate of Opening
The slow opening adjustment can be seen on Page 37, Figure 17. This device is a hydraulic damper which slows down the rate of opening of the second main gas valve to give a smooth main gas ignition. This is preset at the factory at the slowest setting and will need no further adjustment. If a new valve is fitted, then remove the plastic screw on top and with a small screwdriver turn the "V Start" screw fully clockwise towards the
Where fitted, the start gas valve train is fitted with a pressure regulator and two start gas safety shut off valves. The start gas regulator is used to adjust the burner firing rate during the start gas phase of these models.
10.4.2 Main Gas Valves
See Page 37, Figure 17 for the position of the burner pressure regulator. This must be used to set the burner pressure indicated in the data tables in Section 4.
For high/low or modulating burners, the Dungs gas valve has extra features because it is an air/gas ratio control valve. Please refer to the manufacturer’s instructions for setting the controls.
10.4.3 Throughput Adjuster
These valves have a throughput adjuster fitted to the second main gas valve. See Page 37, Figure 17. This will be factory set at fully open on new
10.5 Combustion Testing (all models)
Combustion quality must be tested to prove correct heater operation. Incorrect results will indicate faults with the installation or appliance.
Combustion testing must be carried out with all covers in place. The flue gas is sampled in the flue, within 1 meter of the heater. The values of CO2 should be between 9.5% and 10.0% for natural gas and 11% for LPG, depending upon the model.
The CO will be up to 80 ppm (0.008%) dry, air free, depending upon the model. Temperature rise of the flue gases above ambient should be approximately 160°C to 180°C. Seal the test hole in the flue after testing.
To alter combustion performance, open/close the combustion air damper to reduce or increase these values. Once adjusted to the optimum combustion setting, lock the air damper into position. Repeat the steps in Section 10.2.6.
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