St Paul’s Cathedral gets Hamworthy makeover

Published:  08 June, 2017

Hamworthy, boilers, space heating, DHW

Following 50 years of service, the three steel shell boilers serving St Paul’s Cathedral in London could not be repaired any more and have been replaced with Hamworthy Wessex Modumax mk3 condensing boilers with a total output of 1016 kW. At the same time, new plant to provide domestic hot water was installed.

The cathedral is Grade I listed which posed a series of problems, in addition to the technical issues.

Robin Bunton of Bunton M&E Services advised that replacement boilers were necessary and worked with Mike Crouch, Hamworthy’s agent for the area, and Nick Coates from Blue Print Building Services Design on the specification for the heating and hot-water refurbishment project with clerk of works Martin Fletcher.

The installation comprises two stacks with two boilers in each that can deliver any output from 50 to 1016 kW. These boilers fit through a standard doorway, providing the installation flexibility needed.

Six months before the boilers were installed, two MagnaClean filters were installed to clear sludge and debris from the heating system, followed by a system flush. The boilers and the heating system were separated by a plate heat exchanger. The completed plant room was fabricated and built off-site at Bunton M&E Services’ workshop, dismantled and delivered to site — reducing the total installation time on site to just four weeks.

Flueing requirements were met by running a FuranFlex flue liner down the length of the 30 m rain water chute into the plant room.

Commenting on the success of the project, Robin Bunton says, ‘The speed of heat up has greatly improved. Previously it would have taken a week to heat the cathedral up from cold, but now it only takes one day. The heating runs 24/7 on weather compensation.’

The cathedral is a popular tourist venue, with coach parties using facilities such as toilets and catering in a relatively short period, causing an extremely high peak demand. Two Hamworthy Powerstock glass-lined calorifiers, each with a capacity of 500 l and a recovery time of 18 minutes, were chosen. It was not possible to get a 1000 l calorifier into the plant room, hence two 500 l units.

For more information on this story, click here: June 2017, 121

comments powered by Disqus



Welcome to Modern Building Services Online, the web edition of Modern Building Services (MBS) journal and the UK's most popular Building Services engineering site. Modern Building Services covers the entire Building Services Engineering industry. This site contains archived content from the journal, plus web-specific content.

When you go to our digital edition, you can also access the archive of digital editions.

Modern Building services has a group
on Linkedin - join us!

Construction Week



  • Field Sales Executive

    Successful professional technical salesperson required to sell to consultants and contractors. Unique opportunity to sell ultra-low energy, patented technology, ventilation products from a UK manufacturer. ...

  • Property Surveyor

    Property Surveyor/ Building Service Surveyor needed to work within the Technical Services team for the management of water hygiene/ legionella risk within DCC's property portfolio. We are looking for an experienced and dynamic team member to join our T......

more jobs »


"Is the Building Services industry lagging behind in the implementation of BIM?"