Let’s compare different underfloor heating systems and find out their characteristics, strengths and weaknesses.
Underfloor heating systems have a high level of popularity. Possessing clear advantages – ease of use, long service life, energy saving, floor circuits are simply replacing traditional heating. Comparison and analysis of the effectiveness of various low-temperature radiant heating systems for wall, ceiling, floor show interesting results.
Arrangement of hybrid underfloor heating
- Hybrid underfloor heating
- Specialist discussions and experiments
- Construction (possible) hybrid underfloor heating
- Other details of the hybrid underfloor heating circuit
- Analog signal processing
As it turns out, underfloor heating is the best method with low energy consumption and running costs. However, the traditional underfloor heating scheme is usually based on burning fossil fuels, operates at high temperatures, and uses a lot of energy. Therefore, a hybrid version of the scheme seems logical for consideration.
Hybrid underfloor heating
Solar energy is a clean, renewable energy resource that is attractive to the whole world. Many experts believe that the development of solar energy technologies is essential for sustainable development. Solar underfloor heating is believed to be the best form of heating.
However, the existing solar-powered radiant floor heating system requires additional heating due to the insufficient stability of the solar resource. This resource directly depends on:
- from the season,
- other factors.
Therefore, it is logical to consider the technology of creating a system of photovoltaic and photothermal underfloor heating as a significant research topic for practical application.
The main technological components of the combined construction of underfloor heating are solar cells, a storage tank, a pump system and automation
A simple algorithm might look like this:
- The photovoltaic circuit generates electricity and then stores it in the battery.
- The inverter supplies electricity to the ground source pump.
- The thermal circuit supplies hot water to the underfloor heating system.
Combined underfloor heating with a photovoltaic heating system and a geothermal heat pump is widely discussed by technicians of all levels. The seasonal average of combined underfloor heating shows an improvement of almost 55.3% compared to a conventional heating system. Accordingly, the use of a ground source heat pump in combination with radiators and photovoltaic underfloor heating seems to be a reasonable solution.
Specialist discussions and experiments
The efficiency and CO2 emissions of various underfloor heating systems were discussed in terms of:
- thermal comfort,
- energy consumption,
- impact on the environment.
A series of experiments were carried out to test the performance of the geothermal heat pump circuit in various operating modes. Key indicators of energy efficiency and CO2 emissions have been tested and analyzed to show the benefits of such an operating system.
Photovoltaic collector module of industrial production: 1 – photovoltaic module; 2 – copper absorber; 3 – case; 4 – aluminum frame; 5 – seal; 6 – back sheet; 7 – foam; 8 – pipe outlet; 9 – seal; 10 – copper tubes; 11 – insulation
The performance of photovoltaic (PV) hybrid collectors as part of a solar floor heating system was analyzed. The use of efficient PV solar collectors is preferable to conventional photovoltaic and solar thermal components in terms of potential energy savings.
To assess the performance of PV hybrid systems in terms of power and hot water supply, a floor system model was tested. At the model level, it is demonstrated that the configuration of the PV underfloor heating significantly improved the thermal and electrical characteristics.
Construction (possible) hybrid underfloor heating
The idea behind the design of a hybrid underfloor heating system is to form coordinated operations with the two systems. It combines the photothermal radiant floor heating circuit with the photovoltaic radiant floor heating circuit.
The photothermal radiant floor heating system is based on a scheme where a solar thermal collector converts solar energy into thermal energy. Then, through the hot water pipes, the floor surface is heated by thermal energy.
The photovoltaic floor heating circuit is powered by AC heating cables laid in the floor. Photovoltaic cables are heated by supplying power from the centralized network and transfer thermal energy to the interior of the room. The design of such a floor heating system is shown in the picture below.
Hybrid floor heating scheme: 1 – solar panel; 2 – battery; 3 – constant current stabilizer; 4 – inverter; 5 – solar thermal collector; 6 – temperature sensors; 7 – circulation pump; 8 – geothermal pump; 9, 10 – flow sensors; 11 – outlet pipe; 12 – electromagnetic valve; ВР – water reservoir; Charger – charger; ES – electric meter; RPP – the location of the floor
The solid line outlined in bold orange indicates the photothermal design of the radiant floor heating. In parallel, a photovoltaic floor heating system is being built. AC heating cables and water pipes are, in fact, intertwined and evenly laid in the floor of the room with the installation of a temperature and humidity sensor.
The photothermal underfloor heating system at the expense of the solar collector heats the water circulating with the help of a pump through the storage water tank. The second circuit of the water tank is hot water circulating through pipes in the floor area using a geothermal pump.
The controller processes the indoor temperature signals and regulates the opening of the electric control valve installed in the underfloor heating circuit. The regulation is carried out by means of a flexible adjustment PID controller algorithm in accordance with the temperature setpoint.
Heat collection and supply circuits are equipped with temperature sensors and flow sensors that process and control:
- power consumption.
Other details of the hybrid underfloor heating circuit
With a photovoltaic floor heating circuit, solar cells convert solar energy into electricity, which is fed to the inverter through a DC regulator. The inverter converts 48V DC to 220V AC, which is required to power the AC heating cables.
Industrial made converter that can be successfully used for home hybrid floor heating device
Solar cells also provide 48VDC and 24VDC to control and charge the battery. The DC regulator contains diodes that prevent the charging current from flowing back to the solar panels.
The 220V AC power supply allows the heating cables to be powered directly. It also supports the ability to charge the battery through a charger, which provides additional battery charging in case of a solar panel power shortage.
Using electricity at night to charge the battery and then starting up the floor heating system during the day is another energy saving method. Current sensors (A1 ~ A3) and voltage sensors (V1 ~ V3) in the power circuit are used to monitor current and voltage.
The monitor data is used to evaluate the normal operation of the entire device. The entire PV power supply circuit is equipped with:
- various circuit breakers (K1 ~ K5),
- contactors (KM1 ~ KM5),
- fuses (FU1 ~ FU2),
which are necessary for remote automatic or manual control.
The presented option assumes the use of a flexible PID controller, which monitors and controls the entire floor heating. The controller contains DO, AI and AO ports, a power supply port and an RS485 communication port.
DO ports output digital instructions to control the on / off control of the respective contactors. Each indicator corresponding to a contactor indicates an on / off status. Some of the contactor coils are mainly powered by a battery (48V DC) and an inverter (220V AC).
It should be noted that the KM4 and KM5 coils are powered from the 220V AC mains, since the KM4 and KM5 control battery charging and heating cables from the main power source. This part of the power supply must be separated from the photovoltaic power generation circuit. Thus, underfloor heating is guaranteed to work in the event of a lack of solar energy for a long time.
Analog signal processing
AI ports are used to acquire analog signals including AC and DC voltage and current signals, level sensor signals, room temperature and humidity signals, electrical control valve opening signals, and heat and heating collection and heating temperature and flow signals. …
Port AO1 is used to output the electric control valve open command. The controller collects and monitors the operating time of photothermal floor heating and photovoltaic floor heating. The battery port provides constant current to power the controller and touchscreen.
- Touch screen.
- Multifunctional power meter.
The marked circuit components communicate via the RS485 communication port. The various operating values of the entire circuit are monitored on a touch screen that can accept user instructions for controlling valve opening and contactor on / off. Element K10 is a DC circuit breaker that is used with a manual power circuit breaker.
The inverter provides 220VAC for the heat recovery pump, heat supply pump and water supply solenoid valve. Contactor K9 is a general AC breaker.
Contactors K6 ~ K8 are AC circuit breakers for each branch. When any of the KM6 ~ KM8 coils are energized, the corresponding contactor is closed. Accordingly, the equipment receives energy from the power source.
During normal circuit operation, the K1 ~ K10 circuit breakers are closed and the system can be remotely controlled by touch screen. In case of emergency, the operation of the devices will be immediately stopped by the circuit breakers. published by econet.ru
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