Canterbury-based nursery Riverside Children’s Centre provides childcare and cooked meals for children aged 6 weeks to 5 years. Philip Kiss, Building Services Engineer at Canterbury City Council, turned to Hamworthy for a reliable and efficient solution to replace the existing heating and hot water system. The chosen products have already achieved cost savings of 16.7% after 7 months of operation thanks to high efficiency in combination with advanced built-in boiler controls.
Ian McGregor, Area Sales Manager at Hamworthy Heating, identified Hamworthy’s Stratton mk2 wall hung condensing boiler with stainless steel heat exchanger and a Halstock HS305UV stainless steel calorifier as an ideal replacement. The boiler delivers an output of 43kW, a gross seasonal efficiency of 95.75% and features an extensive Siemens LMS controls platform to supply heat and hot water the most efficient way. With a turndown ratio of up to 5:1, the boiler can closely match the heat from 8kW up to 43kW, avoiding wastage of energy.
The Stratton mk2 boiler was provided free of charge by Hamworthy as a test site for the new wall hung boiler range when it was launched in 2016.
The chosen calorifier delivers a continuous output of 390 litres per hour at a differential temperature (difference between hot water system flow and supply temperature) of 44°C. This model is suited for combination with smaller output boilers such as the chosen Hamworthy Stratton mk2.
Canterbury has very (temporary) hard water, caused by dissolved calcium hydrogen carbonate, which is why a water softener has been installed. Initially falling as rain, the water absorbs carbon dioxide from the air, transforming it into carbonic acid. When water is softened, it is no longer saturated by dissolved hardness which makes the contained acid more aggressive. This can become a problem for storage vessels and as such, the corrosion-resistant stainless steel products were chosen.
Balancing hot water supply and low-temperature underfloor heating
The nursery has underfloor heating which can only take a maximum water temperature of 50°C to avoid structural damage to floors. To cater to those needs, a hot water priority strategy using the boiler’s built-in controls was adopted.
“I have worked with Ian over many years and he had a clear understanding as to what we needed: Primarily reliable delivery with maximum possible energy savings. So, I was confident enough to let him take the lead on designing the control regime.”
Ian explains the chosen control strategy for the children’s centre
“We wanted to make full use of the built-in LMS controls of the boiler for controlling the heating and hot water. The Halstock calorifier heats up quickly – in only 38 minutes from cold. When required, the heating circuit is switched off and all power directed to hot water production at 80°C in non-condensing mode which takes merely a few minutes to top up water in the water heater. As soon as excess heat has been distributed around the hot water supply primary circuit, heating operation goes back to lower temperature condensing mode. This way, the underfloor heating circuit is protected from high temperatures and boiler running time in less efficient non-condensing mode is minimised. All this is done from the boiler itself, without the need for extra controls.”
Gas savings after less than a year
When the new gas bill arrived in July 2017, the new boiler had been running for 7 months. Philip comments,
“For the year ending July 2016, our annual consumption was 152,433kWh at a cost of £9,545. For the year ending July 2017, it was 129,995kWh at a cost of £7,951 which means we’re looking at savings of 22,438kWh and £1,593. The new boiler has only been running for just over half a year and we’ve saved 16.7% on expenditure for gas.
It’s great to already be benefiting from cost savings. We’re looking forward to comparing bills again in 2018 once the boiler has been running for a whole year.”
Dependable energy-efficient heating supply supported by intelligent controls
After the heating and hot water upgrade, Riverside Children’s Centre now benefits from a reliable, highly energy-efficient stainless steel boiler coupled with a stainless steel calorifier with fast recovery time which effectively saves money. The automated controls ensure heat is supplied on a hot water priority basis, optimising energy savings by minimising the use of the boiler in non-condensing mode for hot water production.
About working with Hamworthy, Philip concludes,
“I have enjoyed working with Hamworthy on this project because both their sales managers, Ian and Stuart, know what they are talking about and look after me. I know that I will receive sensible and practical answers to my questions.”