RG66004088 - Rev 00
MXE
All copying, even partial, of this manual is strictly forbidden.
12
WATER CIRCUIT
When setting up the water circuit of the unit, it is advisable to follow the directions
below and in any case comply with local or national regulations.
Connect the pipes to the chiller using flexible couplings to prevent the
transmission of vibrations and to compensate thermal expansions.
It is recommended to install the following components on the pipes:
- Temperature and pressure indicators for routine maintenance and monitor-
ing of the unit. Checking the pressure on the water side will enable you to
verify whether the expansion tank is working efficiently and to promptly detect
any water leaks within the equipment.
- Traps on incoming and outgoing pipes for temperature measurements,
which can provide a direct reading of the operating temperatures.
- Regulating valves (gate valves) for isolating the unit from the water circuit.
- Metal mesh filter (supplied), with a mesh size no greater than 1 mm,
to be fitted on the inlet pipe to protect the exchanger from scale or
impurities present in the pipes.
- Air vent valves, to be placed at the highest points of the water circuit for the
purpose of bleeding air. (The internal pipes of the unit are fitted with small
air vent valves for bleeding the unit itself: this operation may only be carried
out when the unit is disconnected from the power supply).
- Drainage valve and, where necessary, a drainage tank for emptying out the
equipment for maintenance purposes or when the unit is taken out of service
at the end of the season. (A 1” drainage valve is provided on the optional
water buffer tank: this operation may only be carried out when the unit is
disconnected from the power supply).
It is of fundamental importance that the incoming water supply is hooked up
to the connection marked “Water Inlet”.
Otherwise the evaporator would be exposed to the risk of freezing since the
antifreeze thermostat would not be able to perform its function; moreover the
reverse cycle would not be respected in the cooling mode, resulting in additional
risks of malfunctioning.
The dimensions and position of plumbing connections are shown in the
dimension tables at the end of the manual.
The water circuit must be set up in such a way as to guarantee that the nominal
flow rate of the water supplied to the evaporator remains constant (+/- 15%)
in all operating conditions.
A standard feature of MXE units is a device for controlling the flow rate (flow
switch or differential pressure switch) in the water circuit in the immediate
vicinity of the evaporator.
12.1
SYSTEM WATER CONTENT AND CHARGING OF
EXPANSION TANK
In models without a water storage tank it is necessary to assure that the content
of water within the system does not fall below 4.5 litres/kW. This level is
necessary to prevent the water temperature from falling below the indoor unit
enabling threshold during defrost cycles.
N.B
kW in reference to rated capacity
The expansion tank is pre-charged to a pressure of 1.5 bars, sufficient for
systems with a maximum height difference (H in the figure at the side) of 13
metres.
For greater height differences, refer to the table below in order to adjust the
charging pressure of the expansion tank accordingly.
In no case should you exceed the maximum height difference Hmax = 35 m.
Hmax=35 m
LEGEND
H
Height difference of system
p
i
Charging pressure of expansion tank
C
max
Maximum system water content
Models
H
(m)
p
i
(bar)
C
max
(l)
<13
1,5
145
15
1,7
133
20
2,2
105
25
2,7
77
30
3,1
49
M
X
E
009-
021