Invented nearly 70 years ago, Thermostatic Radiator Valves (TRVs) remain essential to the full efficiency of most ‘wet’ domestic central heating systems. Bjorn Sejr Nielsen, Marketing Director of Danfoss, looks at how TRV technology has developed over the decades to bring even more energy savings and fitting flexibility.
Accurate control
First available as long ago as 1943, TRVs are the original room temperature controls and their role in energy saving is still recognised today. Changes to Part L Building Regulations, which came into force in October 2010, state that all new heating systems should now have at least two heating zones and one hot water zone. In addition, each of these heating zones should have at least one room thermostat to provide boiler interlock and individual radiator control such as TRVs. Apart from not complying with building regulations, a home with no heating controls is missing out on significant energy savings.
Preventing overheating
Accurate control of room temperatures ensures only essential heat is generated. Effective ‘zone control’ saves householders energy, and money, by preventing the expensive overheating of parts of the house that are unoccupied or need to be kept at a lower temperature, like bedrooms. It can also be used to take advantage of passive solar gain in highly glazed areas such as a conservatory, or adapt to different occupancy patterns in, say, a home office, which may only be used at certain times or days of the week.
Cost-effective solution
Installing separate heating circuits with their own programmable controls is one way to comply with Part L zoning. However, a simpler and more cost-effective solution is to fit TRVs _ and because they require no external power to operate they are a truly ‘green’ zone control solution. TRVs sense room temperature changes in individual rooms, including extraneous ‘free heat’ from sunlight, appliances and occupants, and adjust the flow of heated water only where it’s needed through the relevant radiators. With a typical payback time of less than two years radiator thermostats represent a really attractive proposition that’s relatively easy to sell to householders.
Best practice
The Good Practice Guide 302, the Government’s authorative document covering domestic heating controls, endorses the TRV as an energy saving solution by recommending radiator thermostats for all ‘wet’ systems (both combi and regular boilers), whether these are installed to defined ‘Minimum Set’ (basic control function) or ‘Best Practice’ standards.
The Guide, and Part L, specifies TRVs on all radiators expect in rooms with a room thermostat, which is already doing this job. However, where an automatic by-pass valve is installed in a heating system, radiator thermostats may be fitted to all radiators. Many boiler manufacturers specify by-passes and minimum flow rates through the boiler heat exchanger to maintain peak system efficiency, irrespective of load. Part L insists on the use of automatic by-pass valves in such installations as a by-pass alone or manual by-pass valve is not considered adequate.
Energy savings
The TRV has become firmly established as an energy saving heating control and thousands are installed in UK homes every year, either as part of a new heating system or an upgrade to improve the efficiency of an existing system. However, although every professional heating installer will be familiar with the primary functions of the TRV, not all may be aware how this simple yet highly effective product has developed over the years. Energy saving developments in TRV technology are being driven by increasingly stringent regulations and by end-users who are struggling to afford rising energy bills. Also, with everyone talking ‘green’ it’s not surprising that products like the TRV, which reduce energy consumption and so help cut carbon emissions, have found a ready market in both the private and social housing sectors.
Flexible positioning
TRV innovations in recent years have covered the full spectrum, from size and style to increased efficiency and easier installation. The latter is demonstrated in developments like the bi-directional TRV. Unlike the traditional ‘cone and seat’ type valves, which need to be fitted on the flow rather than the return side of the radiator, the new bi-directional valves can be installed horizontally or vertically, in flow or return, making for much more flexible positioning. And now there’s even a ‘flow-selectable’ bi-directional valve, offering an instant solution to the common problem of system noise or ‘water hammer’. This can occur when a valve is fitted the wrong way round _ a quick turn of the valve’s revolving feature and the problem is solved..
New generation valves
However, perhaps one of the most significant developments in terms of energy efficiency has been the programmable electronic TRV. These new generation valves offer both time and temperature control for each room, contributing to lower fuel bills for householders and a greener environment. Extra energy savings can also be made with innovative open-window functions, which prevent heat being wasted by closing the valve if the thermostat detects a significant drop in room temperature when a window is opened.
Keep it simple
Although TRVs are clearly becoming more sophisticated in terms of functionality this shouldn’t be at the expense of ease of fitting and use. Installers don’t want to spend hours getting to grips with a complicated manual, and there’s no point developing an all-singing all-dancing TRV that the average homeowner finds too difficult to use. Clear digital displays, pre-installed programmes, and simple push-button operation are just some of the user-friendly features of the latest electronic TRVs, and I believe we’re likely to see further developments in the user interface similar to those used in Smartphones and touch-screen devices.
The TRV has come a long way in the past 70 years and modern versions offer highly accurate, intelligent control of domestic heating systems. It’s estimated that eight million UK homes are currently without any form of heating control. That’s a huge untapped market for installers looking to increasing their sales whilst helping their customers cut energy costs with fast, easy to fit TRVs.
Danfoss is a leading manufacturer of world-class heating controls, from programmers and thermostats to TRVs and motorised control valves, with factories in the UK and Denmark. The company’s extensive product range is supplied through a national network of stockists. As part of its commitment to improving the knowledge and profitability of its customers, Danfoss offers a programme of installer training courses and CPD seminars, covering all aspects of domestic central heating techniques.