Checking Diaphragm Expansion Vessel And System Pressure; Checking The Gas Type - Viessmann VITODENS 200-W Installation Instructions Manual

Vitoden 200-W pages 44 -

Checking diaphragm expansion vessel and system pressure

Note
Carry out this test on a cold system.
1. Drain the system, or close the cap valve
on the expansion vessel and reduce
the pressure, until the pressure gauge
indicates "0" .

Checking the gas type

The boiler is equipped with an electronic
combustion control unit which adjusts the
burner for optimum combustion
in accordance with the prevailing gas
quality.
• The boiler can be operated with natural
gas in the Wobbe index range 10.0 to
16.1 kWh/m 3
without conversion.
• Adjust the burner for operation with
LPG (see "Gas type conversion"
overleaf).
Wobbe index ranges
Gas type
Delivered condition
Natural gas E (G20)
After conversion
LPG P
56
4/9/07 7:56 pm
(36.0 to 58/0 MJ/m 3 )
Wobbe index range
kWh/m
12.0 to 16.1
20.3 to 21.3
Page 13
2. If the inlet pressure of the expansion
vessel is lower than the pre-charge
pressure of 6.75 bar, top up until the
inlet pressure is raised to 6.75 bar.
3. Top up your heating system with water
and vent until the filling pressure of a
cooled system is 0.1 to 0.2 bar higher
than the inlet pressure of the diaphragm
expansion vessel.
Permiss. operating pressure: 2.5 bar
1. Determine the gas type and Wobbe
index (Wo) by asking your local mains
gas or LPG supplier.
2. Convert the burner for operation with
LPG (see overleaf).
3. Record the gas type in the benchmark
commissioning check list on page 71.
3 MJ/m 3
43.2 to 58.0
72.9 to 76.8