702
Thermo G
7 Servicing
–
Measuring and adjustment of the exhaust CO
2
content as required (see 7.6).
7.6
Measurement and adjustment of the
exhaust CO
2
content
The exhaust CO
2
content is to be measured and adjusted
as required according to the level given in the technical
data under the following circumstances:
–
as part of a function check
–
in case of combustion irregularities
–
after repairs at the burner
–
after gas pressure regulator replacement
–
after an application customization
–
if the heater is operated with CNG (natural gas) which
methane content is less than 95 Vol%
–
after installation of a replacement burner
–
for long-term use at high altitudes
NOTE:
The CO
2
level of the Thermo G 300 replacement burner is
adjusted by the manufacturer for use with CNG of class H.
7.6.1 Measurement of the exhaust CO
2
content
The exhaust should not be measured directly at the
exhaust outlet of the heat exchanger, as this may cause
inaccuracies.
Exhaust fumes should be sampled from the exhaust pipe
in a distance of 350 mm after the heat exchanger.
In the case no exhaust pipe is connected, for the measu-
rement a flexible pipe of 500 mm length (see accessory
catalog) can be used.
At this point also the measurement of the exhaust gas
temperature should be performed.
An increased exhaust gas temperature can e.g. indicate a
sooted heat exchanger.
1. After a combustion period of approx. 3 min. measure
the CO
2
content in the exhaust and compare it to the
target value in the Table 201 „Technical data heater“
in Chapter 2.
7.6.2 Adjustment of the exhaust CO
2
content
The exhaust CO
2
content adjustment is performed using
an adjustment screw, accessible at the heater above the
gas port (see Fig. 701).
By the screw the gas flow rate at the gas inlet and thus the
ratio of the gas-air mixture is changed at a given vacuum.
Adjust the exhaust CO
2
content as follows:
1. Check input voltage at the heater.
2. Let the heater run approx. 3 minutes.
3. Measure the CO
2
content in the exhaust and compare
it to the target value in the Table 201 „Technical data
heater“ in Chapter 2.
4. Insert a hex screw driver into the hole above the gas
port (see Fig. 701) and turn the adjustment screw until
the target value is reached.
Fig. 701 Adjustment of the exhaust CO
2
content
CO
2
–
CO
2
+
