![background image](http://html1.mh-extra.com/html/daikin/ewat_b-series/ewat_b-series_installation-maintenance-and-operation-manual_2460302012.webp)
D-EIMAC01706-18EN- 12/32
Water circuit for the connection of the unit
2.8.1
Water piping
Piping must be designed with the lowest number of elbows and the lowest number of vertical changes of direction. In this
way, installation costs are reduced considerably and system performance is improved.
The water system must have:
1. Anti-vibration mountings in order to reduce transmission of vibrations to the structures.
2. Isolating valves to isolate the unit from the water system during maintenance.
3. In order to protect the chiller, the flow switch must be protected against freezing by continuous monitoring of the water
flow in the evaporator. In most cases, on site, the flow switch is set to generate an alarm only when the water pump
turns off and the water flow drops to zero. It is recommended to adjust the flow switch in order to produce a "Water
Leakage Alarm" when the water flow reaches 50% of the nominal value; in this case the evaporator is protected against
freezing and the flow switch can detect the clogging of the water filter.
4. Manual or automatic air venting device at the system highest point.; drain device at the system lowest point.
5.
Neither the evaporator nor the heat recovery device must be positioned at the system’s highest point.
6. A suitable device that can maintain the water system under pressure (expansion tank, etc.).
7. Water temperature and pressure indicators to assist the operator during service and maintenance.
8. A filter or device that can remove particles from the fluid. The use of a filter extends the life of the evaporator and pump
and helps to keep the water system in a better condition.
The water filter must be installed as close as possible to
the chiller
, as in Figs. 6 and 7. If the water filter is installed in another part of the water system, the Installer has to
guarantee the cleaning of the water pipes between the water filter and the evaporator.
Recommended maximum opening for strainer mesh is:
0.87 mm (DX S&T)
1.0 mm (BPHE)
1.2 mm (Flooded)
9. Evaporator with an electrical resistance with a thermostat that ensures protection against water freezing at ambient
temperatures as low as -20°C.
All the other water piping/devices outside the unit must therefore be protected against freezing.
10. The heat recovery device must be emptied of water during the winter season, unless an ethylene glycol mixture in
appropriate percentage is added to the water circuit.
11. If case of unit substitution, the entire water system must be emptied and cleaned before the new unit is installed.
Regular tests and proper chemical treatment of water are recommended before starting up the new unit.
12. In the event that glycol is added to the water system as anti-freeze protection, pay attention to the fact that suction
pressure will be lower, the unit performance will be lower and water pressure drops will be greater. All unit-protection
systems, such as anti-freeze, and low-pressure protection will have to be readjusted.
13. Before insulating water piping, check that there are no leaks. The complete hydraulic circuit must be insulated to prevent
condensation and reduced refrigeration capacity. Protect the water pipes from frost during winter (using for example a
glycol solution or a heating cable).
14. Check that the water pressure does not exceed the design pressure of the water side heat exchangers. Install a safety
valve on the water pipe downstream of the evaporator.
2.8.2
Installing the flow switch
To ensure sufficient water flow through the evaporator, it is essential that a flow switch be installed on the water circuit.
The flow switch can be installed either on the inlet or outlet water piping. The purpose of the flow switch is to stop the unit
in the event of interrupted water flow, thus protecting the evaporator from freezing.
The manufacturer offers, as optional, a flow switch that has been selected for this purpose.
This paddle-type flow switch is suitable for heavy-d
uty outdoor applications (IP67) and pipe diameters in the range of 1” to
6”.
The flow switch is supplied with a clean contact that must be electrically connected to the terminals shown in the wiring
diagram.
The flow switch must be set up to intervene when the water flow of the evaporator is lower than the minimum flow declared
for the unit in question.
2.8.3
Heat recovery
Units may be optionally equipped with heat recovery system.
This system in made by a water cooled heat exchanger located on the compressors discharge pipe and a dedicated
management of condensing pressure.
To guarantee compressor operation within its envelope, units with heat recovery cannot operate with water temperature of
the heat recovery water lower than 20°C.
It is a responsibility of plant designer and chiller installer to guarantee the respect of this value (e.g. using recirculating
bypass valve).