Unical HP_OWER 250N, Руководство пользователя и инсталлятора

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19 OPERATING LIMITS
19.1 EVAPORATOR WATER FLOW RATE
The nominal water flow rate is referred to a ∆T equ al to 5°C, between the evaporator’s inlet and outlet temperatures. The allowed
maximum flow rate is corresponding to ∆T=3°C. Higher values may produce too high pressure drops. The allowed minimum water
flow rate is corresponding to ∆T=8°C. Insufficient val ues of water flow may produce too low evaporating temperatures according
to the operating status with the intervention of safety devices which would stop the unit and, in some particular cases, the water
can freeze in the evaporator coil which can breakdown the refrigeration circuit 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
HP_OWER
250N 350N 500N
Cooling capacity for reference [kW] 21,02 26,90 36,21
Minimum water flow rate that to ensure [L/s] 0,63 0,80 1,08
As a first approach, and in the absence of other detection systems, the proper flow rate 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 static pressure indicated on the curves shown in paragraph 15 for the respective models and if it’s necessary change
the settings (for the related circulator) that are reported in the control manual.
19.2 COLD WATER TEMPERATURE (SUMMER OPERATION)
The minimum temperature that is allowed at the evaporator’s outlet is 5°C: for lowest temperatures the unit should undergo
some necessaries structural modifications and different setting parameters of the controller with micro-processor. In this case
please 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 TEMPERATURE (WINTER OPERATION)
Once the system is working at the right temperature, the inlet hot water temperature should not be lower than 25°C; the lowest
values that are not related to transitional or start-up stages may cause system’s malfunction and possible compressor
breakdowns. The maximum outlet water temperature should not exceed 60°C. At this temperature, the power consumption and
performance in terms of C.O.P. are enhanced if the outdoor temperature is higher than 5°C, even if the unit is still able to work up
to the limit of -15°C (-25°C for versions with injection).
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.
The maximum power consumption of the heat pump alone will take place during the operation with outlet water temperature of
60°C and outdoor temperature of -15°C(-25°C for versions with injection)
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 allowed range of the outdoor temperature
goes from -15°C (-25°C for versions with injection) to 40°C as a function of the water outlet temperature as indicated in the below
table.
Operation limits
Water chiller mode
Ambient temperature Min.-10°C Max. +46°C
Water outlet temperature Min. +5°C Max. +25°C
Heat pump mode
Ambient temperature (standard/injection version) Min. -15/-25°C Max. +30°C
Water outlet temperature (standard/injection version) Min. +25°C Max. +60°C/+65°C
Heat pump mode for sanitary hot water
Ambient temperature with maximum water temperature 48°C (standard/injection version) Min. -15 / -25°C Max. +40°C
Ambient temperature with maximum water temperature 55°C (standard/injection version) Min. -15 / -25°C Max. +35°C
Water outlet temperature (standard/injection version) Min. +20°C Max. +60°C/+65°C
(*) With additional electric heater (not supplied)
Below the operation limits are reported, in the case of air conditioning and sanitary hot water production.