Don’t undervalue the TRV

Don’t undervalue the TRV

Gareth Ash, Marketing Manager at Danfoss, considers the sometimes underrated role of the TRV in reducing domestic heating costs and carbon emissions.
Invented by Danfoss back in 1943, radiator thermostats (TRV) remain essential to achieving the optimum efficiency of most ‘wet’ domestic central heating systems. This claim is supported by heating control tests carried out in the Energy House at Salford University. The results highlighted the importance of TRVs to ensure satisfactory heat distribution around a dwelling. If set up correctly they can help consumers cut their energy use by maintaining the required temperature for each room rather than just heating the whole house, including unoccupied rooms, to the same temperature.

Whilst every professional installer will be familiar with fitting TRVs, we believe the true energy-saving value of this essentially simple device is not always fully appreciated. In addition to the potential savings in fuel consumption already mentioned, when they are used as part of a hydronically balanced system TRVs will also prevent unwanted overflows, and wasted energy, through the radiators. According to some figures, this could bring up to 36% of extra savings for homeowners compared with constantly open manual valves.
Informed choice
Although ostensibly working to the same principle, the TRV has evolved significantly since the concept was first introduced by Danfoss all those years ago. There are now many more options on the market, including electronic solutions that utilise wireless technology to provide end-users with effortless (and more energy efficient) heating control via a smartphone app. This vast array of products can be daunting for even the most experienced installer. However, making an informed choice, rather than simply sticking with what you know or picking the cheapest option, can be key to keeping customers happy and securing new and repeat business.

Understanding some of the main differences between the various products on the market, such as the type of sensor, can help avoid potentially costly call-backs if the TRVs don’t perform as promised. As every heating professional knows, TRVs work by sensing the air temperature around them and regulating the flow of water through the radiator to which they are fitted. Inside each TRV head is a sensor containing a material which expands as the room temperature warms up and contracts when it cools down. The sensor is connected to a valve seat inside the body that opens as the sensor contracts and closes as the sensor expands to allow more or less water through. Whilst this concept is in itself very effective, the material used inside the sensor will affect the TRV’s overall performance and accuracy. This is because different materials have different thermal properties, initially and over time. Needless to say, a TRV with a sensor that offers a faster response to a change in ambient temperature means improved comfort and energy savings for end-users. On average, response times range from just 1 minute for an Electronic TRV, 10 minutes for a Gas sensor, up to 22 minutes for Liquid and as much as 40 minutes for a Wax sensor. We believe this difference is something installers should be aware of when selecting TRVs for their customers.

Smart heating
Given the increase in smart home devices, from sound systems to refrigerators, it’s not surprising that heating controls have also got smarter, like the Danfoss Eco radiator thermostat, for example, which allows the programming of individual radiator thermostats via Bluetooth technology using the Danfoss Eco app. The intuitive app makes it simple for households to program the heating to suit their daily schedule and keep rooms comfortably warm when occupied, and cooler when empty. An electronic plug-and-play solution, Eco demonstrates how TRVs have evolved to become part of the ‘Internet of Things’. Quick and easy to install, these next generation controls enable consumers to experience some of the key benefits of intelligent heating for a relatively low investment cost.

Getting the balance right
Although the process of hydronic balancing is sometimes neglected during the installation and commissioning of a domestic heating system, it is essential to ensuring that the system operates at optimum efficiency for maximum consumer comfort at minimal operating cost. In a properly balanced system, water flows equally to individual radiators and prevents cold or hot spots emerging, or the property not heating at all. As well as the discomfort factor this can cause, the efficiency of an unbalanced system is significantly reduced, increasing energy consumption and fuel bills for consumers. In another example of recent innovations in TRV technology, Danfoss has now created a high efficiency TRV with a built-in differential pressure controller for fast and simple hydronic balancing. By demonstrating a constant flow in all conditions, the Danfoss RAS-B2 ensures each radiator receives an equal flow of hot water. This not only optimises end-user comfort but also means that the return temperature is lower (condensing boiler efficiency is best at below a return temperature of 55o C) and the pump can run at a lower speed. Furthermore, pre-setting of the desired flow is done on the valve, rather than on the lockshield, which it is estimated could save installers up to two hours of valuable working time.

Regulatory recognition
In light of the proven benefits, the latest version of the European Performance of Buildings Directive (EPBD) has made individual room controls, such as self-acting TRVs, a mandatory requirement (where feasible) for any new heating installation: and if they are not present in existing homes with radiators they should be fitted when the boiler is replaced. The long-awaited update to Part L is expected to follow the EPBD’s lead, which would mean installing basic radiator valves will no longer be an option. At Danfoss, we believe regulatory recognition of the TRV is good news for the industry and end-users. Properly selected and installed, modern TRVs offer an easy-to-fit solution for heating engineers and an affordable investment for their customers with an estimated payback period of just two heating seasons. So let’s give the humble, yet mighty, TRV the credit it so clearly deserves.
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