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Thomas Rotherham College

Tuesday August 2 2016


Stokvis Energy Systems is supplying an energy efficient solar heating system to provide hot water to staff and public toilets as part of the plan to reduce energy and carbon emissions at Thomas Rotherham College, an educational establishment for 16 to 19-year- olds in Rotherham, South Yorkshire.

The system – comprising two Ecotube DF120 solar evacuated tubes, a pump station, control system, solar thermal single coil 210-litre buffer vessel, unvented mains kit and electric immersion heater backup – will result in estimated energy savings of around 2,600 to 3,000kWh a year.

The absorber fins in the Ecotube panel capture the sun’s energy and heat a fluid passing through the central pipe. This fluid is pumped to the hot water cylinder where it heats the stored water. The system is highly energy efficient and exceptionally cost-effective to install.

The initial enquiry for the Stokvis solar heating system was made by the college’s site manager after being particularly impressed by it following his visit to an energy exhibition last year.

Malcolm Aitken, Regional Sales Manager – North & Scotland of Stokvis Energy Systems, explained:

“Thomas Rotherham College previously had conventional gas-fired storage water heaters that supplied toilets within part of the building. The site manager decided that this was not cost effective because the toilets were only used intermittently. The college therefore installed point of use electric water heaters in a number of the toilets. Subsequently, it was able to remove the old storage heater and generate hot water via the solar system augmented by electric immersion heaters.”

Because of its experience across a range of technologies from high efficiency boilers and plate heat exchangers for the generation of hot water to a range of renewable solutions, Stokvis Energy Systems was able to offer an integrated package incorporating both solar and conventional heat generation technologies.

Stokvis arranged to supply its equipment via solar heating installer, Eco2Solar based near Birmingham. In this way, the college was able to take advantage of the beneficial VAT rate extended to charitable institutions.

Independent laboratory tests in Switzerland have revealed that Ecotube produces 750kWh per sq m per year in direct heating mode (850kWh in pre-heat mode) compared to the industry standard of 528kWh per sq m.

Ecotube panels use an indirect system to heat water. The heat transfer fluid passing through each panel is a solution of water and non-toxic antifreeze, which allows great performance even on clear frosty days in winter.

This fluid absorbs heat from the Ecotube array and is pumped to a heat exchanger (coil) in the hot water tank. The heat then passes into the water, and the cooled fluid is pumped back to the solar panel.

The pump is controlled by an electronic device that detects the temperature difference between the solar panel and the hot water tank. When the temperature in the panel is lower than the temperature in the tank, such as on cloudy days or at night, the system remains on standby.

However, when the sun raises the temperature in the panel to 4 deg C above the temperature in the tank, a differential temperature controller switches on the pump to operate the system.

Mr Aitken concluded:

“Being an enlightened establishment in terms of environmental protection, Thomas Rotherham College recognised that the Ecotube solar heating system was the most cost-effective and environmentally friendly way of reducing its CO2 emissions while, at the same time, cutting fuel costs.”

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