Airwell PAC HT 14-7 Podręcznik danych technicznych - Strona 3
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General Characteristics
Introduction
This new range of PAC HT air/water high temperature heat pumps offers the
special feature of producing hot water at 65 °C at outdoor temperatures down
to -20 °C, while guaranteeing a high COP .
For outdoor temperatures above +7° C, the PAC HT supplies water at 55 °C
with a single compressor.
Consequently, this PAC HT unit is ideally suited to replace a traditional hot
water boiler in producing Domestic Hot Water (DHW).
The patented technology
uses two-stage compressors that provide :
Higher COP :
➜
In fact, in a two-stage system, each compressor operates at a low
compression ratio, i.e. 3:1 compared with 12:1 for single-stage
compressor systems.
This improves the compressors' service life and reduces electricity
consumption.
Same heating capacity maintained even with low outdoor temperatures :
➜
As compressor efficiency is maintained, PAC HT performance is hardly
affected, even at low outdoor temperatures.
Remarkable adaptability in terms of matching supplied capacity
➜
to heating requirements thanks to the possibility of using each
compressor stage separately :
The PAC HT controller chooses the optimum compressor staging
configuration according to the demand for heating and the heat emitters'
operating temperatures.
Optimised Domestic Hot Water production :
➜
Both for producing DHW and Heating, the controller determines the
compressor staging best suited to the DHW tank coil's heat exchange
capacity, while taking account of the outdoor temperature. At the end of
the heating phase, the DHW temperature is very close to the condensing
temperature without an unnecessary energy consumption.
Scope of application
The PAC HT is mainly designed as a replacement for the boiler without altering
the rest of the installation.
Bodywork and structure
Steel bodywork coated with oven-baked epoxy paint coating.
The unit base is equipped with large openings under the coil for condensate
or de-icing water drainage.
Removable panels on all sides allow access to the electrical box and to the
refrigeration and hydraulic circuits. Closed bodywork protection index : IP 24.
Compressors
Maintenance-free Scroll type compressors produce a high efficiency with low
sound levels.
The two-stage circuit equipped with 2 compressors with an unrivalled
capacity ensures the best possible matching of supplied capacity to heating
requirements.
Anti-vibration pads under the compressor prevent the transmission of any
vibrations to the bodywork.
Water side exchangers
Brazed plate construction operating on a counter flow configuration in Winter
mode to ensure excellent heating performance.
Air exchanger
Treated with a hydrophilic coating to assist condensed water drainage.
The exchanger is sized to avoid clogging, maintain its performance in sub-
zero temperatures and cut the time and frequency of de-icing operations.
Fans
Reinforced polypropylene, low-speed helicoidal fans with optimised fan blade
profiles to ensure efficient air flow at an extremely low sound level.
Fully-enclosed motor, maintenance-free bearings, automatic reset overheating
protection device. The fan blades are shielded by plastic grilles for personal
protection in accordance with health & safety standards.
Refrigerating circuit
The patented refrigerating
circuit enables each compressor to be used
independently or in two-stage mode.
The circuit, factory-filled and tested, includes a filter-dryer, two thermostatic
expansion valves, high and low pressure safety devices and all the equipment
specific to two-stage technology.
Electrical box
The electrical box contains all the components for PAC HT operation and
notably the system's protection devices : compressor protection circuit
breaker or fuse, protection fuse, standard start-up current limiter for single-
phase units, phase sequence controller for three-phase units.
The microprocessor based controller integrated in the box controls all the
PAC HT's functions with the help of a room terminal and temperature sensors.
Safety functions controlled by the controller :
High and low pressure safety, lack of water flow, lack of refrigerant
charge, low evaporation pressure, high and low outlet water temperature
limits, winter frost protection, compressor short cycling protection.
Diagnosis of failures with history of 150 latest alarms (code, description,
occurrence time and sensor values at the time of alarm).
Other functions managed by the controller :
Water temperature control (inlet and outlet) depending on outdoor
temperature and ambient temperature (water law).
Choice of compressors for optimised efficiency.
De-icing the outdoor exchanger in winter.
DHW production management.
2-stage extra electric heating management.
Management of boiler relief without additional kit (not compatible with
extra electric heating).
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