Installation Manual PA Pro III
online
–
2018-03-16 Page 11 of 30
-
Material type in tube
Good heat transfer decreases the error caused by the wall from best to worse copper - iron
- stainless
–
plastic.
-
Material thickness in tube
Dimension, pressure and material define thickness thicker tube wall increase need of
insulation.
-
Condensation
It is important to avoid condensation on or near sensor as this will have a significant impact
on temperature reading.
-
Ice formation
If ice is allowed to form around sensors (condensation on cold tubes) this creates an
insulation.
Importance of accuracy
A service check can allow a higher tolerance for errors than an inspection to validate that
performance is according to contract.
Note that even if temperatures on secondary side do not have any impact on capacity and COP of
refrigeration process, they will, if nominal data is taken from manufacturers, strongly impact these
reference data.
We advise common sense to be applied, with special attention to discharge and suction line sensor
on the refrigerant side due to high dT and risk of condensation.
For best accuracy, remove dirt, paint and corrosion, and avoid pushing sensors inside existing
insulation - cut a hole in insulation instead. Always use heat transfer paste and aluminium tape to
make insulation on cold tubes so that condensation or ice formation cannot take place on sensor.
Smaller size copper tube
minimum 60 mm x 8 mm tight insulation pressed against
tube (thickness 8 mm or 3 turns of insulation tape)
Larger size CU (> 35 mm/1.5")
minimum 100 mm x 8 mm tight insulation pressed against
tube (thickness 8 mm or 3 turns of insulation tape)
Steel/plastic/stainless piping
minimum 15 cm x 8 mm insulation
5.2.2
Compensating for changes in temperature sensor cable length
No configuration has to be made when using black 1-wire sensors and when using the entire white
5 m cable or the entire red 10 m cable of a PT1000 temperature sensor. If a PT1000 cable is
shortened or lengthened the change in resistance needs to be compensated for. The standard
temperature offset (0.35 K) needs to be
increased for a longer cable
or
decreased for a
shorter cable
. The white cable got a resistance of 0.07 K/m and the red cable 0.035 K/m (using
all four leads in pairs).
Fill in the offset for each changed PT1000 in the Configuration document and send to ClimaCheck
support.
5.3
1-wire temperature sensors
1-Wire temperature sensors are bus sensors and the measured values are not affected by the
resistance in the cable between the master (PA Pro III) and the slave (sensor). However, there are
some limitations on how to wire these sensors. The preferred topology can be seen in Figure 3.
