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Connection of the ETS temperature sensors
The ATW-MINI controller uses a set of digital ETS sensors to monitor the temperature. Each of the sensors is
identified by an address that is assigned to it in production. If you add or change sensor, the new sensors have
to be addressed using the ATW-SW software. When replacing the controller module, all connected sensors must
be adressed again.
ETS sensors of probe type are supplied with a 2m cable. The wall type sensors are supplied with a 10m cable.
The total lenght of the sensor cable should not be longer than 10 m (because of possible electromagnetic
interference). If you need to extend the cable, use an shielded cable with at least one twisted pair. Connect the
inner wires of the cable to XETSG and XETS+ terminals. The shield of the extension cable must be connected
only at one end - to the chassis of indoor unit or switchboard. Do not connect the other end to anything!
Without this grounding method the cable works as an antenna - this significantly impairs the sensors resistance
against interference. The ends of the original sensor cable are connected to the inner wires of the extension cord.
Be sure of the correct polarity as the original sensor connection.
The noise immunity can be improved by using the ferrite anti EMI components strung on the sensor cable.
Connection of the heat pump to the heating system
Planning
A high-quality project of the heating system is equally important as the used water or quality of the material.
Insufficient flow of the heat supporting medium leads to an increase of condensate water and this will
dramatically worsen the COP. Incorrectly projected regulation system has the same effect. On the contrary, high
speeds of flow lead to corrosively erosive attack. Insufficient size of expansion tank relates directly to a
possibility of the heat system corrosion.
Installation and start-up
Any small changes made to the project during its realization may cause the heating system being faulty. The
quality of connections, welding and soldering procedures, wash-out and first heating-up are the main points for
customer satisfaction. To save costs, only the authorized personnel is allowed to perform the heating system
installation.
Used materials and equipment
This depends on the project of the heating system. The designer should avoid a solution using various materials,
for example copper piping, aluminium radiators, steel boiler etc. It is impossible to protect such system against
different types of corrosion in normal life. It is always profitable to use certificated materials. This applies also for
the supporting materials, such as sealing, soldering flux and irons. The main reason for the total corrosion of the
heating system is the usage of plastic pipes without oxygen barrier for floor heating.
Circulating water quality
The quality of the circulating water is decisive for the long-term failure-free operation of the heating system.
Characteristics of the used water vary depending on the locality of the drill hole and source. Bear in mind that
water similar in characteristics to drinking water is not suitable for heating systems without special treatment.
The following water parameters are necessary for heating systems: water hardness, salinity, acidity and content
of melted gases in water.
Water hardness is indicated by the volume of the Ca2+ and Mg2+ salts, which through the change of solubility in
operating conditions create practically insoluble carbonates. Hard water scale is formed mainly on the bivalent
source and its negative effects are made by the following process. First, a compact heat insulating layer is
created. This reduces the total capacity of the source and causes local overheating of the exchanger. Owing to
the unequal dilatation in the place of overheating, the layer compactness is broken. Loose scale pieces get to the
circulating water and gradually block the cooling exchanger and the regulation valves. During the scale
formation, carbon dioxide is released and causes system airlock and general corrosion. It is also necessary to
replenish the missing water, which is usually unconditioned and brings undesirable effects into the system again.
Salinity describes the level of different melted salts in water. In practice, there are the Na+, K+, Fe2+ cations and
the Cl- and SO42- anions. The Fe2+, Cl- and SO42- ions encourage the corrosive processes in the heating system.
Water salinity is directly proportional to its electric conductivity. High water salinity facilitates electrolytic
corrosion, especially when different types of metals (copper, iron) are used.
The main criterion for corrosion processes in the system is its acidity (pH). To minimalize the corrosion effect of
water, the pH value should correspond to the applied materials. Note that the pH value suitable for steel is not
proper for aluminium and vice versa.
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