How to maximise boiler efficiency

How to maximise boiler efficiency

Did you know that installing a high-quality condensing boiler is not enough to ensure maximum energy efficiency? Gareth Ash, Marketing Communications Manager at Danfoss, explains how fitting modern TRVs provides a simple way for installers to boost condensing boiler efficiency and achieve increased energy savings for their customers. Whilst today’s condensing boilers are highly efficient their efficiency can be impaired by components that do not allow the boiler to reach its full potential, resulting in energy bills that are much higher than they should be. To ensure customer satisfaction and savings, installers need to look at the complete system and how components for precise room temperature control affect overall boiler performance.

Modern condensing boilers only achieve maximum efficiency when they operate in condensing mode most of the time, which requires a low return water temperature. However, a new condensing boiler is often connected to the existing room controls, such as manual radiator valves or old TRVs without pre-setting, neither of which are designed to provide a low return water temperature. While the boiler still works this way, it is significantly less efficient. The boiler is not running in condensing mode, increasing energy usage for householders who are already counting the cost of soaring energy bills. By matching a high-performing condensing boiler with high-quality components, such as fast-reacting TRVs and automatic balancing of radiators, installers can fine-tune condensing boiler efficiency.

It’s all about low return water temperature

As soon as a boiler goes from non-condensing to condensing mode the efficiency skyrockets. Getting the boiler into this mode requires a return temperature of below 55 degrees C. A manual radiator valve will simply restrict the flow through the valve and offers no control over the room temperature. Modern TRVs provide an optimum heat control solution. The TRV limits the flow through each radiator by regulating the room temperature to the desired leveland allows the boiler to operate most efficiently. Typically, in a wet heating system with manual radiator valves the boiler will only operate in condensing mode about 5% of the time, compared with 80% if TRVs are fitted. There is, therefore, a major boost in operational efficiency in a heating system with TRVs.

Getting the right balance

As well as installing modern TRVs, correct balancing is widely recognised as one of the keys to ensuring a heating system works as per the design specification. As every heating professional knows, hydronic balancing is the process of optimising the flow of water in a hydronic heating (or cooling) system by balancing the system pressure. Balancing ensures that the water flows equally to individual radiators and so prevents cold or hot spots occurring, or radiators not heating at all. As well as the discomfort factor, the efficiency of an unbalanced system is significantly reduced, increasing energy consumption and fuel bills for householders. In order to achieve maximum heating efficiency common issues such as cold radiators also need to be addressed. To tackle this, some installers may consider putting the system pump onto a higher speed or putting the boiler thermostat onto a higher temperature setting. Although this might seem like a quick fix compared with hydronic balancing, it may well lead to increased noise in the system, overheating and will most certainly increase the system’s energy consumption.

Making balancing quick and easy

The Danfoss RAS-B2 Dynamic Valve, a 2-in-1 temperature control and automatic balancing valve, now makes it quick and easy to ensure that the heating system is always perfectly balanced. Once mounted and in conjunction with the pre-setting tool on the Danfoss Installer App, installers can simply calculate the setting for the valve by entering the desired flow and return temperatures for the system as well as the size and type of radiator, before setting the valve to the number indicated in the app. The valves will automatically perform the balancing of the entire system right away. The distribution of heat is even and to the pre-set levels, regardless of partial loads and weather conditions, thanks to a pressure independent regulator inside the RAS-B2. As well as improving condensing boiler efficiency by ensuring a lower return temperature, this innovative solution also reduces customer complaints about under-heated or over-heated rooms. And to make pre-setting ultra-easy,. Studies suggest that precise room temperature room control and correct balancing of the heating system could offer energy savings of up to 36% (when compared with constantly open manual radiator valves). On top of this major selling point, the installation of TRVs is typically paid back in less than 18 months (maybe sooner given the current high energy costs) and occupants gain improved indoor comfort with the desired temperature in all rooms. Condensing boilers have big potential to run more efficiently with the right adjustments and component match. Properly selected and installed, modern TRVs provide a solution that maximises boiler efficiency with minimum disruption and cost. Given these benefits, Danfoss is urging installers to spread this important message to their customers so they don’t miss out on significant energy savings. For more information visit