i-SHWAK V4
Inverter air/water chillers and heat pumps with wall-mounted indoor unit and remote condensing outdoor unit
38
19
OPERATION LIMITS
19.1 Evaporator water flow rate
The nominal wate
r flow rate is referred to a temperature differential of ∆T=
5°C between inlet and outlet of the evaporator. The
allowed maximum flow rate is
corresponding to ∆T=3°C; higher values may cause too high pressure drops. The allowed minimum
water flow rate is the one
corresponding to ∆T=
8°C (except for the model i-SHWAK V4 06 for which the maximum value of
∆
T is
6,25°C and for
for “i
-
SHWAK V4 08” model the maximum temperature difference is ∆
T=7,5°C
)
. Insufficient water flow may in fact
cause too low evaporating temperatures with the intervention of safety devices for stopping the operation of the unit and, in
some particular cases, the water can freeze in the evaporator coil causing the refrigeration circuit to break down or causes the
increasing of the condensing pressure with the shutdown risk of the appliance and the compressor could be damaged.
We enclosed below a most accurate table showing the minimum water flow that should be ensured for the plate heat exchanger
in order to have the proper operation of unit as a function of the model (note: the water flow switch is used for preventing the
freezing sensor from failure in the case of insufficient water flow but it does not ensure the minimum flow rate required in order
the unit can work properly).
Models
i-SHWAK V4
06
08
10
12
14
16
Required minimum water flow rate [m
3
/h]
0,71
0,86
1,08
1,30
1,48
1,64
Required maximum water flow rate [m
3
/h]
1,88
2,30
2,87
3,47
3,95
4,37
As a first approach, and in the absence of other detection systems, the proper water flow for getting the best performance from
your unit can be found at maximum speed of the circulator, using the pressure gauges for controlling the pressure difference
between the return and the delivery water on the outside water connections of the unit and make sure that such value is equal or
less than the available head pressure indicated on the curve shown in Chapter 16 for the respective models
and if it’s necessary
you change the settings (for the related circulator) that are reported in the control manual (MCO).
19.2 Chilled water production (summer operation)
The allowed minimum temperature at the evaporator’s outlet is 5°C; for
lower temperatures, the unit should undergo some
necessaries structural modifications and different setting parameters of the controller with micro-processor. In this case contact
our company for the feasibility study and evaluation of changes to be made according to your requests. The maximum
temperature that can be maintained at the outlet of the evaporator is 25°C. Higher temperatures (up to a maximum of 40°C) can
anyway be tolerated during transitions and start-up phases of the system.
19.3 Hot water production (winter operation)
Once the system is working at the right temperature, the inlet hot water temperature should not to be lower than 25°C; the
lowest values that are not related to transitional or start-up stages may cause incorrect working operation to the system with the
possible breakdown of the compressor. The maximum outlet water temperature should not exceed 58°C. At this temperature, the
power consumption and the performances in terms of C.O.P. are enhanced when the outdoor temperature is higher than 5°C,
even if the unit is still able to work up to the limit reported in the envelope.
For higher temperatures than those pointed out, especially if have a concomitant with the reduction of the water flow rate, it may
cause abnormalities to the normal operating of the unit, or the safety devices act in critical cases.
19.4 Ambient air temperature
The units are designed and manufactured to operate, in summer operation, with the condensate control, with outdoor air
temperatures ranging between -10°C and 46°C. While operating as a heat pump, the admitted outdoor air temperatures range
changes from -20°C to 40°C depending on the water outlet temperature as indicated in the below table.
Operation limits
Water chiller mode
Ambient temperature
Minimum -10°C M46°C
Water outlet temperature
M5°C M25°C
Heat pump mode
Ambient temperature
Minimum -20°C M30°C
Water outlet temperature
M25°C M58°C*/+63°C**
Heat pump mode for sanitary hot water
Ambient temperature with maximum water temp. 38°C
Minimum -20°C M40°C
Ambient temperature with maximum water temp. 55°C
Minimum -15°C M35°C
Water outlet temperature
M20°C M58°C/63°C**
(*) The setting of the unit is 57°C, the value of the maximum temperature takes into account the hysteresis of 1°C present on the
parameter.
(**) With a supplementary electric heater (optional)
