Case Study: Rinnai continuous flow hot water replaces stored system at Essex School

Holmwood House was opened in 1922 as a boy’s school by Mr and Mrs E F Duggan with the aim ‘to develop the individuality and abilities of each child, to make them self-reliant and adaptable’. The world has changed a great deal in the school’s first century, but it still upholds those underlying values.

Except for wartime evacuation, the school has remained on the same site, two miles from the centre of Colchester. In 1985 Holmwood House began accepting girls, and in 2006 the nursery was opened in Great Horkesley. The site needed to upgrade and update its hot water delivery system. The new hot water delivery system – comprising of 3 x Rinnai N Series 1600i units – was installed by SDF Mechanical.

Shaun Fuller, who started SDF in January 2018 has been working within the HVAC industry since he was 17 years old and has gained a wide range of experience over the last 13+ years. From working on domestic boilers within households to large industrial steam boilers in factories, he has a wide range of skills to meet all requirements throughout all sectors. Since starting the business Shaun has progressed SDF Mechanical Services into having a large customer base in all sectors in the industry and built close relationships with them. SDF Mechanical Services are Gas Safe and Oftec Registered and have a wide range of qualifications to be able to carry out various different types of work to the highest of standards.

For Rinnai Harry Barton commented: “The diminutive size, lightweight nature (less than 30kg) and high performance of 960 litres per hour at a 50 degree rise ensured that the Rinnai solution was an ideal system for this project. Having run some capital expenditure, operational expenditure, and carbon modelling, we also saved the school money and reduced its carbon footprint. “

Rinnai’s hot water heating units have been certified by the British Standards Institution (BSI) for use as hydrogen blends ready. The range was subjected to rigorous testing and analysis by the BSI and the product range is ‘Hydrogen BLEND 20% ready’ with the I2HY20 gas category certificate for all its products.

All Rinnai continuous flow condensing water heaters are guaranteed to provide limitless volumes of temperature accurate hot water (in excess of 1500 litres per hour) this is combined with market leading turn down ratios (13-1) and 96% efficiency.

Extensive testing also demonstrates that multiples of its existing ranges are retrospectively compatible with future hydrogen blending including all N series models already installed in the UK. The Rinnai Sensei N Series continuous flow hot water heater range offers a more compact, enhanced combustion design that allows for easier installation, superior operational performance as well as ease of serviceability.

The Rinnai Sensei N Series is the first ever continuous flow hot water heating unit manufactured with stainless steel heat exchangers to be available in the UK – this gives a greatly extended working life at optimum performance to each of the four models in the range. Added to this are the market leading extended warranties, that accompany the hydrogen Blend-ready and Bio-LPG ready instantaneous water heaters.

The four models are:

  • N1600i giving 954 litres per hour (at 50 degrees)
  • N1600e (external) also giving 954 litres per hour (at 50 degrees).
  • N1300i giving 775 litres per hour and
  • N1300e also giving 775 litres per hours of temperature controlled hot water at 50 degrees.

The two 1600s have load profiles of XXL and are water efficiency class A rated, while the 1300s are load profile XL and are also water efficiency class A rated.

All the range is also low-NOx (Less than 26ppm meaning they gain additional points under BREEAM) and the futureproofed continuous flow water heater utilises Rinnai’s patented advanced burner technology with a 13-1 turn down ratio – the largest on the market combined with 96% efficiency rating. Integral controls on the units enable the water heater to achieve high efficiencies because of advanced burner control and high modulation ranges.

This wide range of modulation means that energy usage is completely optimised as the water heater through smart inbuilt controls will only heat the water to the temperature required thus preserving energy.


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