ONICON System-30 MODBUS BTU - Manual (Page 13)

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System-30 BTU Measurement System MODBUS RTU RS485 04/14 - 0583-1 / 18345
Page 13
THERMOWELL INSTALLATION IN WELDED PIPE
3.3 ELECTRICAL INSTALLATION
All user supplied conduit fittings, junction boxes, etc. are to be installed as required by all
applicable building codes.
3.3.1 Single Mode (4 Pipe) Vs. Dual Mode (2 Pipe) Operation
ONICON System 30 BTU Meters may be configured for single or dual mode applications.
Single and dual mode is a reference to the piping system and not the meter itself. Single
mode (4 pipes) applications are those that always have the same relationship between the
supply and return pipe temperatures. In dual mode (2 pipes) applications the polarity of
the temperature differential (Delta t) reverses; often on a seasonal basis.
IMPORTANT NOTE
The System-30-MOD BTU Meter is designed with one internal (Temp1) and one remote (Temp 2)
temperature sensor. If the meter body is located in the supply pipe then the internal temperature
sensor will indicate the supply temperature and the remote sensor will indicate the return
temperature. This relationship will reverse if the meter body is located in the return pipe. The
location of the meter will also affect the logic used to determine mode 1 and mode 2 operations
for dual mode applications. Single mode energy measurements are absolute measurements and
are not effected by polarity of the Delta t.
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