Thermodynamic panels are designed to produce hot water for both domestic and commercial usage. These systems are more formally known as Solar Assisted Heat Pumps. This term helps to explain how and where this type of product fits into the renewable energy spectrum. A thermodynamic panel is a halfway house between a solar panel and a heat pump. The primary purpose of this product is to provide heat energy in the form of hot water predominantly
The products have been developed as a more efficient alternative to air source heat pumps by including the use of solar gain / radiation. This means that a thermodynamic system can benefit from both the ambient air temperature, like a heat pump, as well as the solar radiation, like a solar thermo system.
This best of both worlds approach will often result in an improved COP (coefficiency of performance). These products have been designed with a life expectancy of roughly 20 years by some manufacturers; however they have only really started to take hold in the UK over the last 6-8 years. Initially there was lots of scepticism and uncertainty surrounding this new renewable energy system as it found its feet in the UK. However, in early the first thermodynamic products were granted Microgeneration Certification Scheme (MCS) approval. This dramatically increased consumer and trade confidence.
The Working Principle
An ecological fluid passes through the solar panel at a temperature of -15ºC, thereby allowing the collection of the energy from the sun, rain and wind. As the fluid is running at negative temperatures, it collects the heat from the air by natural convection, working also at night
The fluid is then compressed, in the Solar Box which causes the fluid temperature to increase. The heat is then released into the circulating water by way of a high performance plate heat exchanger.
Finally, the fluid goes through an expansion valve and will evaporate into the aluminium solar panel and the process repeats.
How does a TD System Work?
A thermodynamic system works by sending a very cold liquid refrigerant around a panel on the outside of a property. The temperature of the liquid is approximately -22°C when it enters the panel. As the liquid flows through the veins in the panel it absorbs heat energy from the air surrounding the panel. This is where the term Thermodynamics comes from, as it is a scientific terms used to explain heat energy and its movements. The liquid refrigerant will vaporise into a gas once its temperature reaches approximately -15°C. This is more commonly known as its boiling point. The gas exits the panel and is circulated back to a compressor inside the thermodynamic unit. The compressor job is to compress the gas and send it under pressure through a heating element or plate. When a gas is compressed is gives off heat energy. The heating element is a way of distributing the heat into the store of water. Once the gas has lost its heat it exits the element and passes through an expansion value, which releases the pressure. This drop in pressure and loss of heat energy means that the gas condenses back to a liquid for the cycle to begin again.
The water inside the thermodynamic unit /cylinder is constantly monitored and kept hot by a thermostat. The thermostat will switch the system off once it reaches its required temperature. Most thermodynamic suppliers will set the stored water temperature of a domestic unit at 55°C. This is considered to be sufficiently hot for domestic hot water purposes, yet remaining safe for use. However, this temperature setting can be amended if necessary. Commercial units can be set at much higher temperature if needed.
Types of TD Systems
There are two main ways that a thermodynamic unit can be set up for a domestic property. The first is to install a small thermodynamic unit, usually no larger than 50cm by 50cm, which is designed to work with a normal hot water cylinder. The water from the standard hot water cylinder is pumped to the thermodynamic unit and is heated over a heating plate. These systems are ideal if you are restricted on space, for example a tight airing cupboard. These systems can be linked up with a maximum of about 250lt cylinder capacity.
The second and more costly thermodynamic system set up is to take out the existing cylinder and replace it with an all in one cylinder/thermodynamic unit. These units come in a range of sizes and cylinder capacities (75, 150, 160, 180, 200, 210, 250, 280, 300, 500lt). This set up is the most efficient way of installing and running a thermodynamic unit, if you have the space. The water is directly heated by a coil/element in the storage tank within the unit. This means there is no heat loss from piping the water to an external heating unit. These systems can be fitted to both vented and unvented hot water systems. Quite often an old copper cylinder with poor lagging is replaced with the new thermodynamic unit, which means because of its modern insulation the heat is also retained more efficiently within the new cylinder. The larger 300lt & 500lt units are more commonly used for places with higher hot water demand, such as restaurants, B&Bs, hotels, hair dressers, farms etc…These larger units would often come with more panels, usually 2 or 4, which helps increase energy absorption and speed up recovery time. Manufacturers typically say that 200lt of water can be heated from normal tap water temperature up to 55°C in approximately 3-4 hours, but once achieved it is then constantly maintained.
What is a TD System made of?
A thermodynamics panel is roughly about the size of a standard door, 2m by 1m. The panels are made from anodised aluminium. The anodizing is an electrochemical process that converts the surface of the metal panel into a non-corrosive, durable finish. Inside the property / premises there would be a main unit. This unit consists of two sections, one of which holds the electronics and working parts, the other contains a water storage area. Thermodynamic units come in lots of different sizes dependent on the amount of water needed and storage capacity. Inside the unit you would find a compressor, circuit board, wiring, heating plate or element, expansion value and a backup immersion heater. Some units also come with a secondary coil built into the storage tank so that the existing boiler or additional heat source can be connected up.
The Benefits of thermo Dynamics?
- water up to 55ºC
- Aluminium Solar Panel with high corrosion resistance
- Retro fits to existing cylinder.
- Compatible with both vented and unvented systems
- Very compact unit
- 5 year manufacturers guarantee for the solar panel
- High Performance Plate Heat Exchanger Suitable for DHW
- Circulation Pump Suitable for DHW
- Environmentally friendly fluid
- Significantly reduces carbon emissions
- The Solar Panel can be mounted on the wall, or roof
- The Solar Box can be hung on the wall or be place on the floor
- No glass or other fragile materials
- Fine European and internationally recognized brand
Will I have hot water when there is no sun?
Yes. The fluid passes through the panel at very low temperatures. It can therefore receive more solar energy than a normal liquid, even on days without sun or at night. Because of this thermo difference, the solar panel can capture the heat existing in the environment and transmit it to the water.
Does the solar box require extensive maintenance care?
Occasionally some maintenance may be required.
At what distance must the panel be from the Solar Box?
At a maximum distance of 12 metres.