Bespoke-designed prefabricated heating solution overcomes challenging plant room restrictions

Sherborne School in Dorset has successfully improved the reliability and efficiency of the heating system serving its Big School Room (BSR) building with the installation of four new Remeha Gas 120 Ace boilers using a Remeha prefabricated cascade arrangement. Remeha is part of Baxi.

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Founded in its current guise in 1550, Sherborne School’s history of educating boys dates back to the 12th century. Given its rich history and reputation for excellence, creating the optimal warm and comfortable learning environment for its students and teachers is a key priority for the School’s estates team. However, refurbishing the heating system in Victorian school buildings like Big School Room can present challenges.

This two-storey building, which looks onto the Courts, was built in 1878 to provide a new assembly hall and classrooms for the School. Until recently, the building had been relying on six increasingly inefficient and unreliable boilers for heating. When they reached end of life, the estates team asked mechanical engineering services company Cosgrove & Drew to evaluate the practical options to achieve a more modern, efficient and reliable heating system.

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Neil Price, Senior Technical Manager at Cosgrove & Drew, said: “The fabric of the Victorian building and the operating temperatures of the heating system presented several obstacles.”

Relocating the plant room to a repurposed room or designing an external packaged plant room were two options that had to be ruled out due to budget implications. Heat pumps also had to be disregarded as a viable option.

Neil invited Baxi to accompany him on a site survey to discuss the achievable solutions within the project parameters. The site survey identified additional hurdles. Access to the plant room was restricted due to its basement location, narrow walkways, stairwells and doorway. The low ceiling inside the plant room was a further complication.

Cosgrove & Drew recommended installing new modular energy-efficient replacement boilers with a Plate Heat Exchanger as the most practical and reliable approach to meet the School’s requirements for a more energy-efficient heating service, minimal disruption and easy future maintenance.

To overcome the space restrictions, Baxi proposed installing four Remeha Gas 120 Ace boilers using a bespoke Remeha off-site fabricated cascade system complete with insulated pipework set and pumps and a specially sized Plate Heat Exchanger (PHE).

Neil Price said: “I’ve used Remeha boilers before and have been impressed by their quality and reliability. So, it was a logical decision to use Remeha boilers on this project. Given the access limitations, the option to install them on a rig made this the obvious choice.”

Working with Cosgrove & Drew, the Baxi team prepared CAD and 3D drawings of the boiler cascade arrangement bespoke to the design parameters and integrated specially sized pump sets and a plate heat exchanger (PHE) into the design. The PHE was recommended to separate the new boilers from the existing heating system and protect them from any debris, corrosion or poor water quality.

In addition to the boilers, pumps and PHE, the rig design included a pressurisation unit, a dosing pot and an expansion vessel. To overcome the limited access restrictions through a narrow doorway, the proposal was for the rig to be delivered in units. These would be bolted together inside the plant room and connected to the existing system. Once the design was agreed, production took place in a factory environment, with comprehensive end-of-line testing.

Neil added: “It’s proved a great solution. The Gas 120 Ace boilers are extremely compact, and the bespoke prefabricated rig design made it possible to achieve a space saving option that not only made access into the plant room easy but fits nicely into the available space for easier future maintenance.”

Reduced installation time was an added advantage, as Neil explained: “A major benefit of using the bespoke designed prefabricated rig service that Baxi offers is the time savings it delivers.

"With no need to size all the individual components and no onsite welding required, on site time and labour was reduced significantly," he continued. "This also minimises disruption which was particularly important as this project took place during term time. Commissioning was carried out by Baxi's commissioning engineers who safety tested the installation.

Neil concluded: "The BSR plant room has been completely transformed on both a practical and aesthetic level. It's great!"

A spokesperson from Sherborne School added: "The installation project went smoothly, and the School is hopeful that the improved performance and reliability will result in reduced gas consumption."

The fully modulating Remeha Gas 120 Ace series is available in 65kW, 90kW and 115kW outputs with bespoke designed cascade options available for greater design flexibility. Extremely compact at only 600mm wide, the Gas 120 Ace range will fit into even the smallest of plant rooms. It is supplied with onboard time and temperature controls, with direct connection to a Building Management System provided as standard to maximise heating efficiency. Its quiet operation, high efficiencies and low Class 6 NOx levels make the Gas 120 Ace particularly suitable for use in schools.

For more on our Remeha Gas 120 Ace range, visit: