Control
The controlling and monitoring system
The basis of the system is the CAREL pCO3- microprocessor controller. Through the PLAN connection, an EVD driver controlling the ExV modulation electronic expansion valve is coupled to the controller.
Task of the appliance:
- Regulate and control the heating mode during the winter period.
- - Regulate and control the cooling mode during the summer period
- - Ensure remote and network access (optional).
- Regulate and control DHW production during the whole year
- Control the electronic expansion valve /ExV/.
The outside temperatures detected by the controller:
- Buffer tank temperature
- DHW (Domestic Hot Water) tank temperature
- Outside air temperature
- Heating flow sensor
- Heating outgoing temperature
The inside temperatures detected by the controller:
6. Heat pump heating water output temperature
7. Heat pump heating water input temperature
8. Ground temperature in
9. Ground temperature out
10. High-pressure side
11. Low-pressure side
12. Evaporation temperature
The 6m long factory-prepared outside NTC temperature sensors are connected to the socket mounted on the back plate of the appliance with a quick couple (see the figure). Therefore they are easy to assemble on the basis of the assembly manual.
Control of the heating temperature
Heat pump appliances are working for a buffer tank in both heating and cooling modes. The main task of the buffer tank is to store such amount of heat which can guarantee that the number of switches per hour of the heat pumps is not more than 6-8. The problem is that if we want to keep the buffer effect then as a result of the mixing occurring in the tank there will be minimum 2-30C temperature difference between the outlet temperature of the heating water and the outgoing temperature of the heat pump which will impair the SPF value.
In order to eliminate the above-mentioned problem, there is a special module built in the control of the VAPORLINE heat pumps.
In this control module, the pCO3 will operate a three-way engine mixing valve in accordance with the signal of a flow detector (2), an NTC temperature sensor (4), as well as the signal of the outside air temperature.
Mode 1
Buffer tank is filled with hot water. Then the heat pump is standing, the cooling circuit circulation pump (C1) is running. Then the control valve (1) is closed, the mixing valve (2) lets the hot water flow only from the
Mode 2
The hot water runs out of the tank (10C temperature fall) – the heat pump starts – the mixing valve (1) is activated (opens) and lets hot water flow of such amount through the by-pass conduit directly from the heat pump that the outgoing water temperature defined by the controller is set.
Mode 3
The tank is filled with water, the circulation pump (C1) continues to operate. Then the GHP stops and Mode 1 is set.
Mode 4
The circulation pump (C1) is stopped. Then the flow detector (2) is switched off, and it will end the control of the mixing valve (1) which will set in the basic position shown in the figure.
The control serves for ensuring the optimum buffer effect and making the heating temperature permanent; it reduces the hysteresis of the controlling and improves the SPF value significantly.
Application of the ExV valve
In order to maximize the SPF value, VAPORLINE heat pumps are equipped with ExV valve. Their task is to supply the appropriate amount of cooling medium to the evaporator. Their control takes place by the superheating.
The superheating is “the necessary wrong” part of the cycle. The superheating kept stable at the lowest value possible will improve the SPF value of the pump. For Vaporline heat pumps, the superheating is kept at the lowest possible value / 30C/.
It alone will increase the achievable SPF (seasonal performance factor) value by 10-30% as compared to the expansion valves.
The figure shows the comparison of the operation of the traditional TEV (thermostatic expansion valves) and ExV valves. It can be seen that the control of the TEV valves changes between wide limits permanently, while the control of ExV is permanent, of low value following its great initial