Pitch Perfect

19th February 2021
HIU Boiler

When refurbishing the heating system at one of its residential housing developments, maximising reliability and efficiency while minimising disruption to the residents was the key concern for Charlton Triangle Homes. Ian Lock, Director of Sales – Newbuild & MO (Multi Occupancy) at Baxi Heating, looks at how, with use of off-site prefabrication, they achieved their goal.


Just a stone’s throw from Charlton Athletic FC’s Valley stadium is Valiant House, a 17-storey residential block run by housing association Charlton Triangle Homes (CTH), part of the Peabody Group.


Ensuring that the building services serving the 93 flats are well maintained and monitored is the responsibility of Peabody’s Electrical and Mechanical Services department. So when, in 2019, the Charlton Board reported signs of deterioration, the team was quick to carry out a rigorous inspection of the services.


The existing heating plant consisted of non-condensing gas boilers, located in a roof top plant room, that supplied heating and hot water services to the individual properties. The team had carried out improvement work to optimise boiler performance a few years previously, but the current survey revealed that boilers were now beginning to operate less efficiently and economically.


A second issue was the gas main feeding the boilers – this was at the end of its life span and needed replacing to comply with new regulations and HSE requirements. SGN, who supply the gas to Valiant House, were also preparing to replace their pipes through the building.


Achieving an efficient long-term solution for the residents while ensuring uninterrupted continued use of the building were the dual goals for CTH and Peabody, who brought in an external consultant to review the findings and present a series of options.


Evaluating the options

Low carbon ground source heat pumps (GSHP) were the first consideration, in line with CTH and Peabody’s wider environmental commitments to reduce their carbon footprint.


However, there was a major obstacle – due to the close proximity of the property to the Valley stadium, ground freezing was a real possibility and concern. “We were keen to explore the feasibility of applying low carbon technologies, but we couldn’t run the risk of freezing Charlton FC’s football pitch,” explained Ian Winterflood, Head of Electrical and Mechanical Services at Peabody.


Another option, to replace the gas main and pipe risers to the building, also had to be rejected. This would have required removing concrete through floors to access the existing pipework, creating extra work to protect the building structure and added costs to run a gas main up the side of the building.


A third option was to relocate the plant room from the rooftop and form a new centralised plant room capable of meeting the demand of the building in a larger, unoccupied space at the rear of the building. This proposal involved installing high efficiency condensing boilers to supply new Heat Interface Units (HIU), indirect cylinders with electric back up and individual heat meters in each property.


Included in this last option was the replacement of the cold-water tanks with new cost-effective sprinkler tanks and fire precaution upgrades.


Practical benefits

A key benefit of relocating the plant room to the ground floor was that it removed the need to run extensive pipework up the building. This in turn would minimise works on the floors and avoid disruption to the residents.


Replacing the ageing, inefficient boilers with new, more energy-efficient condensing boilers – with a life expectancy of 20 years plus – also met the requirement for long-term improved reliability and efficiency and an immediate reduction in carbon emissions.


Once this option had been agreed by the Charlton Board, Milverdene was appointed as project contractor while heating and hot water manufacturer Baxi Heating was asked to support with a total heating and hot water solution.


Taking it off-site

“Involving Baxi Heating from the outset paid dividends,” said Ian. “Consulting with them at the early stages meant that they were able to propose a tailor-made, prefabricated design that would achieve all of our project requirements and reduce the embodied carbon footprint of the refurbishment works.”


Baxi Heating and its subsidiary, Packaged Plant Solutions, recommended installing six Remeha Quinta Ace 115 boilers on an off-site prefabricated skid, complete with pipework, pumps and plate heat exchangers, to meet the specification within the design parameters.


To enable rapid installation of the heating and hot water element in each property, PPS provided the new compact Megaflo ECO cylinders pre-assembled with the associated pipework. Supplying the Baxi HIU unit, together with controls and a heat meter, the prep-plumbed cylinders and first fix rails meant that Milverdene would be able to slide the equipment easily into the existing utility cupboard spaces.


“The major advantage for us was the time saved on site,” explained Ian. “The works began at the start of the year, so with COVID-19 restrictions in place just a few months later, we were running a little behind.


“However, thanks to the solution provided, Milverdene were able to complete the changeover in just one day and then refurbish five properties a day, putting us firmly back on schedule. We also didn’t have to worry about multiple deliveries or materials being left on site as the solutions arrived pre-assembled and ready for installation just when needed.”


With the electrics, radiator sizing and valves checked and a new sprinkler pipe and sprinkler heads fitted, the project was completed on time and budget in June 2020.


So how has the refurbishment been received?


“Charlton Board are delighted – the new plant room looks great and it all works brilliantly,” said Ian. “It’s a fantastic result and we are anticipating considerable energy and carbon savings from our new energy-efficient services.”


“Projecting forward, we will be investigating hydrogen boilers as a non-disruptive route to low carbon heating when the Remeha boilers reach the end of their life.”


Most importantly of all, the residents at Valiant House are over the moon with their new more efficient heating and hot water service and the way in which the refurbishment was carried out. The agreed solution – including the prefabrication element – has proved pitch perfect.