Measuring Ambient Air Temperature; Measuring Flue Gas Temperature - TESTO 325M Instruction Manual

5.3 Measuring ambient air temperature

There are 2 ways to measure the ambient air temperature:
1. Measurement using flue gas probe
If a separate ambient air probe is not connected, the
temperature measured by the flue gas probe thermocouple
during the zeroing phase is used as the ambient air temperature.
All dependent variables are calculated with this value. This type
of ambient air temperature measurement is sufficient for systems
dependent on ambient air.
Ensure that the flue gas probe is located near the intake duct
of the burner during the zeroing phase.
2. Measurement using separate probe
If a separate ambient air probe is connected, the ambient air
temperature is measured continuously by this probe.

5.4 Measuring flue gas temperature

The flue gas temperature is measured via the flue gas probe
thermocouple. The probe pipe has openings at the side so that
the thermocouple is protected and can simultaneously come into
contact with the flue gas.
Ensure that the thermocouple is positioned in the flue gas
flow.
The thermocouple should not be covered by the probe stem
frame. This is the only way to make it possible to measure the
flue gas temperature accurately and consequently to determine
the exact flue gas loss.
The tip of the thermocouple should not touch the protective
casing!
If possible, bend back the tip of the thermocouple.
Inserting probe pipe in flue gas duct
Insert flue gas probe pipe, horizontally if possible, in the
flue gas duct.
Condensation drops running down the probe pipe could lead to a
dramatic drop in the temperature measured.
5. Basic instructions
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