A lesson in heating

In a major schools investment programme, City Building (Glasgow) LLP is currently building 16 new primary schools in Glasgow for the City Council at a cost of over £128 million and each is to have its hot water services supplied through a heat-traced single pipe system using Raychem HWAT self-regulating heating cables. Smith Electrical, a Tyco Thermal Controls distributor partner, has been commissioned to supply and install the HWAT systems by the projects’ electrical controls contractor L-Tec Controls and Kentallen Group.

During extensive specification work with senior personnel within the City Council’s Project Management and Design service it was recognised that a heat-traced single pipe system offers highly effective delivery of hot water services and significant installation and operating cost benefits.


The Raychem HWAT hot water temperature maintenance system is a simple, intelligent and energy-efficient means of ensuring instant hot water is available at every hot tap, including those on dead legs. By heat-tracing the pipework, water temperatures are maintained at a constant 55°C, without any need for secondary recirculation plumbing.


This temperature maintenance solution is not only significantly more energy-efficient than conventional re-circulation systems but, in eliminating return pipework, also offers space, material and installation time/cost savings too.


The heating cable has a flat construction that allows design and installation flexibility and is engineered for direct application onto hot water pipes. The intelligence of the system lies in the combination of the self-regulating heating cables and Smart controls. Raychem HWAT-ECO is a smart control unit that limits the heat output of the self-regulating heating cables according to the specific requirements of the hot water system. It combines the clock time functions with monitoring of the boiler temperature in order to ensure that the system is used solely for temperature maintenance, thus avoiding superfluous heat production and minimising energy consumption.

The use of the HWAT-R heating cable with the HWAT-ECO controller offers the benefit of selecting a desired temperature and increasing the temperature over a time for legionella prevention. As such, the HWAT-ECO controller can be programmed for a cycle of legionella prevention by means of ‘temperature shock’.


Across all of the projects, Smith Electrical is installing over 10,600 metres of Raychem HWAT-R heating cable and 120 HWAT-ECO controllers.

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