Figure 1. Principal layout showing the refrigerant circuit
Figure 2. Change in performance as a function of flow temperature, at brine +0 °C/-3 °C.
Figure 3. Change in heat output as a function of flow temperature, at brine +0 °C/-3 °C.
Qvantum QLC Control System
Qvantum RS/2 is equipped with the QLC control system as standard. QLC stands for Qvantum Logic Controller. The unit is controlled and operated via the principal of liquid condensation or solid/half solid condensation. All control parameters, such as outdoor temperature compensated set-point curve for supply, hot water temperature, and auxiliary heat, are set via the self-instructing control system. Required protection and safety features are built into the QLC control system.
The system is managed via a 5,7″ panel mounted in the heat pump. All parameters can be set via the panel. The panel displays a dynamic flow chart panel with all temperatures and operating modes measured and controlled. The QLC control system also logs temperatures and events, which facilitates setup and analysis. The system communicates via Modbus. Modbus TCP is standard. The system also has a webserver which allows the QLC control system to communicate with a web browser on a PC or cell phone.
As an option, the unit can be equipped with a display that allows for dynamic flow images and extended network functionality.
The temperature to the heating system is controlled according to the selected outdoor temperature compensated curve. Hot water preparation, if such a function is required, takes place via a switching valve.
In bivalent systems, the control system switches on additional heat when necessary and after a time delay. The auxiliary heat can be selected to “take over” the hot water preparation as the first step and thereby release power from the heat pump to the heating system.
The QLC control system can control up to 8 heat pumps in sequence with automatic operating time equalization between the different heat pumps. The QLC control system is configured at commissioning depending on the selected system solution and type and number of heat pumps.
The heat pump can be configured for control via an overlaying external control system if required.
Set points can be changed via Modbus so that the controller’s regulators are set by the master controller. It is also possible to configure the system so that the heat pump is fully controlled by the overlaying external control system. In this case, the QLC control system is used only for alarm and protection functions.
E.g., Temperatures readable via Modbus *)
1: Heat pump heat carrier – in
2: Heat pump heat carrier – out
3: Heat pump hot gas temperature
4: Heat pump brine – in
5: Heat pump brine – out
6: Radiator circuit supply
7: Outdoor temperature
*) See Modbus description for complete information
All relay outputs are also readable. You can thus transfer the operating status of compressors, pumps, fans, etc. which are controlled via the heat pump.
Set points for hot water temperature and control curve for radiator circuit can be read and adjusted. From the expansion valve control unit, the current evaporating temperature, pressure, overheating, the degree of opening of the expansion valve can be monitored via Modbus.
Electronic Expansion Valve
Qvantum RS/2 heat pumps are equipped with two electronic expansion valves. A valve for the evaporator circuit and a valve for the economizer circuit.
The expansion valves have their own electronic control unit with display that shows evaporation pressure, temperature, overheating etc. for the two circuits. Via Modbus, these variables can be transferred to an overlaying control system.
All Qvantum RS/2 heat pumps uses R-407C refrigerant.
Qvantum RS/2 are configured for brine with antifreeze, e.g. bioethanol.
Q32RS/2 and Q41RS/2 has top connections while Q48RS/2 has back side connections, see drawing Q-RS2-32-48-001.
Q65-96RS/2 has back side connections, see drawings Q-RS2-65-81-001 and Q-RS2-96-001.
Top connection is optional for Q65RS/2 and Q81RS/2, see drawing Q-RS2-65-81-001. Q123-192RS/2 has back side connections, see drawings Q-RS2-123-144-001 and Q-RS2-162-192- 001.
The unit is built on a robust stand of galvanized square tubes and covered with an effective sound- absorbing casing, consisting of powder-coated plates with sound-absorbing material on the inside. The top plate is made of patterned aluminum. The top and bottom are also covered with sound-absorbing material. The stand rests on adjustable rubber feet.
The unit is constructed so that all components inside the heat pump are easily available by removing the cover plates, both for maintenance and replacement.
The following options are available:
- Connecting QLC to network.
- Electrical cabinet mounted on the left side of the unit, seen from the front (applies to QG96RS/2 – QG192RS/2). – Hot gas heat exchanger. – Reversible function.
The units are equipped with fully hermetic EVI scroll compressors, 3-phase 400V.
- The evaporator is a brazed plate heat exchanger in stainless steel, insulated with Armaflex insulation.
- The condenser is a brazed plate heat exchanger in stainless steel.
- Economizer is a brazed plate heat exchanger in stainless steel.
- Hot gas heat exchanger (option) is a brazed plate heat exchanger in stainless steel.
- Drying filter
- Sight glass with moisture indication – Electronic expansion valve, pressure transmitter, control equipment with display (Modbus) for the main circuit – Electronic expansion valve for economizer/subcooler circuit (Modbus)
- High- and low-pressure switch, manual reset
- Service valves for pressure measurement
- Rotalock valves
- Pressure protection equipment, high- and low-pressure
The units are test run and calibrated under design conditions using ClimaCheck.