MHS Boilers Ultramax 115, Руководство по эксплуатации и техническому обслуживанию, Страница: 41 / 46

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Measure the dynamic gas pressure at the supply side of the gas valve. This must be at least
18 mbar for natural gas (35 mbar for propane or butane) with the boiler is operating at full capacity.
When multiple appliances are installed in the boiler room, this pressure must be measured with
all the appliances operating at full capacity.
The heat input will be 10% higher in case of butane.
Check the temperature difference (∆T) between the flow and return to the appliance at the water
side. The ∆T must be between 15 and 25 K at full capacity.
Check the appliance at minimum capacity
Adjust the appliance to operate at minimum capacity. At minimum capacity the following settings
must be checked and corrected if necessary:
Settings at minimum capacity
Natural Gas G20 Propane G31 Butane G30
9.2% CO
2
11.0% CO
2
13.0% CO
2
≤ 15 ppm CO ≤ 25 ppm CO ≤ 180 ppm CO
Following the adjustment of the combustion process to obtain the figures indicated above the burner
pressure must be taken to ensure correct operation of the appliance. A differential manometer is
required for this process.
Burner pressure = pressure above burner – fan pressure
Pbb – Pvent Ultramax 73 - 287 0.1+ 0.05 mbar
Adjusting the gas valve Ultramax 73 - 287
Two screws are located on the gas valve which can be used to adjust the gas volume (CO
2
value).
Run the boiler at full load and check the CO
2
value.
Adjust if necessary using the flat screw (Ultramax 73 - 90) or the inbus screw (Ultramax 115
–
287.)
Run the boiler at minimum load and check the CO
2
value. Adjust if necessary using the torcx
screw.
Adjusting the air-pressure switch Ultramax 73 - 287
The air-pressure switch must be set to 80% of the fan speed when pre-purging.
A differential manometer is required for this process.