Sector: Historic building
Building: Listed building plant room refurbishment
Products: Upton modular boiler, Burstock expansion vessel, Chesil pressurisation unit, Clenston air and dirt separator, Horton chemical dosing pot
Application: Space heating 400kW


Upton Country Park is a 140-acre site comprised of parkland, shoreline and formal estate gardens. The park, offering plenty of activities indoors and outdoors, draws countless visitors to Poole each year. Amidst the green scenery lies Upton House, a Grade II* listed Georgian Mansion House which was built from 1816-1818 by Poole merchant Christopher Spurrier.

Three Hamworthy UR430 atmospheric single stage cast iron boilers that were delivering heating to the building had come to the end of their life and needed replacing.

The Solution

For the last nine years, Hampshire County Council Property Services have worked with council officers in Poole to consult on the design of mechanical services which also include heating systems for listed buildings.

Mike Morris, senior property manager for Bournemouth, Christchurch and Poole (BCP) Council, explained,

“We have a limited maintenance budget, and the main thing we are concerned about first and foremost is keeping people warm and dry, so boilers and roofs form a big part of our maintenance programme. It is great we have the opportunity to work with Hampshire County Council Property Services who have been doing this for such a long time. The heating system designs are so well-developed, we feel protected, and it is a safety net for us.”

As a local commercial boiler manufacturer with over 100 years of heritage in Poole, BCP Council also has a long working relationship with Hamworthy.

Mike elaborated,

“All our old boilers are Hamworthy. Some of them must be up to 50 years old now and they’re still going. While we’re aware that we should replace these boilers due to efficiency, it’s not always possible with budget constraints. For a council, it is obviously great if we can buy equipment that lasts this long with the limited funds that are available to us.”

Establishing what needs refurbishing

 

The old Hamworthy cast iron boilers provided heat to the basement, ground and first floor. While BCP Council was looking for a replacement, Hamworthy was investigating a suitable test site for its new Upton boiler. Given the close co-operation between the manufacturer and the council as well as the fact that Upton House matched the name of Hamworthy’s new product, the site received the boiler for the listed building heating system refurbishment free of charge.

The chosen model UF400-2 delivers an output of 200kW per module (400kW combined) of which two are stacked on top of each other. As a modular boiler system, these are compact - even the biggest model in the range has a footprint of less than one square metre while delivering an output of 1MW - and can be taken apart for easier handling. Thanks to their compact size, the boiler modules could be transported down the stairs. Access like this usually complicates refurbishments, but the boiler was sited in the plant room without the need for bigger handling equipment.

 

 

Mike added,

“I was really surprised. When I first saw it, I thought it was one boiler. Then I realised it’s two modules, whereas before we had three big boilers.”

Considerable research and development went into the aluminium heat exchanger at the Upton’s core. A gross seasonal efficiency of up to 96.5% ensures the boiler delivers economical heating to Upton House.

The built-in Siemens LMS controls system also allows sequencing of up to 16 boiler modules which further helps improve efficiency and even use across the installation.

Due to the Upton modular boiler’s small size, there is now more space in the plant room, making it easier to access equipment. This has been used for additional Hamworthy ancillaries to future-proof the equipment for maintenance.

As the refurbishment was carried out in winter, a temporary boiler was required to bridge the gap between the removal of the old and installation of the new boiler. It was placed outside the building with hoses also run externally. This all had to be co-ordinated with events using the function rooms downstairs and daily operations of the council offices on the first floor of Upton House in order to neither disturb visitors nor council workers.

Accommodating old and new installation

The existing heating system is open vented. As is common with this type, oxygen ingress can occur, causing corrosion and the build-up of sludge. For this reason, and as it already suffered from poor circulation and was prone to blockages, a system chemical clean and flush was carried out. Due to its age, the concern was what problems would occur when the system was pressurised. For this reason, a plate heat exchanger, connecting (and hydraulically separating) secondary and primary circuit, was installed. This allows an adequate system flow through the boilers and protects them from magnetic sludge and debris present in the secondary circuit. New pipework has been used in the primary circuit which the Upton boiler is connected to.

 

 

The old system is fed from a tank located in the roof from where it gets its static head pressure which was kept for the secondary circuit. As part of the boiler replacement design, numerous valves are installed at low and high points of the system. This allows to isolate sections and flush them again at a later point when the proposed plan is to replace the existing heat emitters.

To create the pressurised primary circuit which the Upton boilers require, a Hamworthy Burstock expansion vessel and Chesil wall mounted single pump pressurisation unit were installed. A Hamworthy Clenston air and dirt separator to catch any further debris and Horton dosing pot to introduce chemicals such as corrosion inhibitor into the system have also been added to the secondary circuit.

To accommodate the new boiler, the gas supply had to be upgraded, too. Additionally, a new flue was required to deal with the condensate and pressure in the new system which posed another challenge.

Refurbishment vs conservation

As a Grade II* listed building, Upton House is subject to rules ensuring that any works do not affect its appearance. This means the new commercial boiler flue had to meet strict guidelines and aesthetic requirements. It was designed and relocated from its original position and moved to the middle of an internal quad, so it could not be seen from outside the building.

 

 

Mike commented,

“While we do understand the conservationist’s concerns of visual impact on the building, we have to make sure that health and safety isn’t compromised. We’re pleased to have found a solution. The design managed to let the flue terminate at a relatively low level. It was also painted, so it matches the colour of the building. It looks much better now – the old flue was rather unsightly and the new one is basically entirely hidden from visitors’ sight.”

Any development of the building also requires a refurbishment and demolition survey which is intrusive, as there is always a risk that a wall that is being drilled into can contain asbestos.
Health and safety, costs and quality are of concern for the council when choosing who they are working with and what products to use.

Mike continued,

“We have to not only watch the money we spend but also make sure the contractors we choose carry out quality work, following all health and safety guidelines. It’s about quality, price and getting the right people.”

Making use of built-in boiler controls and further planned work

While the old heating system had a finite form of control, the new boiler modules are set up to run in sequence from the built-in boiler controls. Both running at minimum modulation allow for better system efficiency than only one operating at high capacity. The boiler is connected to combined room sensor controllers, also provided by Hamworthy, installed in the basement (storage of materials and consumables), on the ground floor (function rooms, often used for conferences and other events such as weddings) and first floor (office space for the co-ordination of council activities). These three different so-called ‘heat zones’ have been set up with different temperatures and start up times to accommodate individual area use.

 

 

Before, the building users had to turn the heating in the entire building on or off. With the new zone control, each floor can now be operated at different hours and reduce energy wastage thanks to dedicated room sensors and control valves. With the installation of an external air sensor, the heating flow temperature now also regulates depending on outside temperatures (weather compensation), reducing energy wastage. Generally, the new boiler modulates its output depending on the heat requirement. However, owing to the existing installation of temperature-sensitive fan convectors in the building which inadvertently shut off when flow temperatures are too low, the boiler’s ability to fully compensate is currently constrained. While the Upton operates at 85/65°C maximum flow and return temperature, the maximum secondary system flow and return temperature is then at 80/60°C for the heat transfer to take place on the plate heat exchanger. This is why a limited flow and return temperature weather compensation setting has been used.

 

 

 

BCP Council is planning to remove the fan convector heaters as part of its ongoing refurbishment to enhance the aesthetic aspect of Upton House, and to improve the weather compensation They are going to be replaced with period-style radiators made from steel for an authentic look.

Noticeable improvements and the Hamworthy experience

Mike comments,

“We’re experiencing better circulation. The heating zones and control accuracy of the system is a vast improvement. Everything is much more comfortable for the staff and visitors. We’ve also improved the visual aspect by upgrading the flue.”

About working with Hamworthy he concludes,

“I’ve known Hamworthy all my life, I really wouldn’t want to go anywhere else. Their support was exceptionally good. Trevor Struck, our local contact, is quick to respond and always happy to assist. As a council, we’re keen on building long-term relationships and working with Hamworthy has been what we’re looking for.“

Can we help you with a listed building heating plant refurbishment? Get in touch.