Danubius Hotel, London
Sector: Hotel and Leisure
Building: Hotel plant room refurbishment
Products: Wessex ModuMax mk3 boiler
Application: Space heating 3,048kW, DHW
Located by Lord’s Cricket Ground, Regents Park and the renowned Wellington Hospital in central London, the Danubius Hotel is a popular destination for travellers and business people alike. With 360 bedrooms/suites and a fitness centre, a reliable heating and hot water supply is crucial. Prior to the hotel heating system refurbishment, this was provided by 14 cast iron atmospheric boilers with a total output of 3,850kW. However, faulty components and other issues indicated the end of their life.
The plant room consisted of the following:
• 14x cast iron boilers split into two banks of seven boilers with individual shunt pumps
• Separate primary circulating pump (which was grossly undersized for the system)
• AHU circulating pumps
• Fan coil unit circulating pumps
• 2x split 500mm single skin flues with a N+1 bi-fucated fan
• Pressurisation unit with undersized expansion vessels
• 8x 750 litre indirect hot water calorifiers with plate heat exchangers on an open vented system
Given the setup, a careful planning process was crucial to ensure a smooth transition to the new system.
Challenges of a busy hotel
While the hotel had to be kept running 24/7 during the change, constant incoming travellers from local airports put extra pressure on, making down time impossible. SPIE had to find a compact boiler with high maximum working pressure and heat output to accommodate the hotel heating and hot water supply to the eleven floors. Together with Hamworthy’s sales manager for the area, Noel Lally, four Hamworthy Wessex ModuMax mk3 WM254/762V modular boilers with a combined output of 3,048kW including pipe header kits and a remote signal kit were identified as the ideal solution. This model consists of 3 boiler modules stacked on top of each other and can operate at a working pressure of up to 10 bar which was needed to match the height of the building. At the core sits a stainless steel heat exchanger that comes with a 10-year warranty. A small footprint of 0.74m² per boiler stack makes it easy to transport and site in narrow plant rooms.
SPIE’s senior project manager commented,
“We chose the Wessex ModuMax mk3 boilers due to their slim profile and the 10 bar working pressure. It’s also efficient, streamline, compact and easy to use. The alternative, a competitor product, only had a safe working pressure of 6 bar. I chose the pipe header because they’re a simple piece of kit with a plug and play installation. When the boilers are all lined up and within a couple of hours the headers bolted to them, it sure does look impressive to your clients. Easy to install, just nuts and bolts and a level.
For the controls, I chose the interface kit to give the boilers full rotation via the building management system to ensure even use across the equipment. It also allows full modular control to suit the system characteristics, meaning the boilers will match the load and operate as efficiently as possible.”
Updating the commercial boiler flue system
A change from atmospheric to condensing boilers meant the flue system needed to be reviewed. Firstly, the stainless steel liner up to the roof – approximately 40 metres – was removed. With the use of CCTV, the SPIE team inspected the concrete fabricated existing flue. The challenging flue installation was overcome by utilising FuranFlex composite liners in the existing chimney stacks to deal with the condensate and pressure of the new boilers. After applying the flue liner, they cut a spigot into the wall to be upgraded to 600mm up to the flue dilution fans from which it was reduced to 500mm to the main stack.
The project manager added,
“We used an N+1 configuration on the flue dilution fan system with differential pressure switch piped across the fan chamber so that in the event of a failure, we had a backup and automatic changeover would occur.”
Separating old from new
SPIE’s contract signed with the building owners was based on zero complaint strategy which meant absolutely no complaints to avoid damaging costs. Originally, the pipework and valves were intended to be reused. But due to failing valves letting by and an uninterrupted stream of hotel guests, SPIE UK’s senior project manager decided to install a whole new 12-metre-long 400mm low loss header and interconnect the Wessex ModuMax mk3 boilers to maintain a primary heat source. Then slowly (at low peak) demand, cut the pipes to each separate circulating system, and integrate to the low loss header. This meant new power supplies, isolators, variable frequency drives (VFDs) and pipework needed to be ready for the cut in. This was done to avoid disruption to the existing heating circuits. To accommodate this process, existing pipework was frozen by Industrial Piping Freezing Services Ltd (IPS), pipes cut, and new flanges welded in by IPS and new isolation valves/regulating cut in.
The work was extensive. The existing main plant room housed the main boiler plant and hot water calorifiers, and there was a small plant room that accommodated all ten circulating pumps. Installing the new low loss header and relocating the main primary circulating pumps down with the boilers meant it was an ideal opportunity to relocate all ten circulating pumps down where the old atmospheric boilers once used to sit. This also included the installation of new isolating valves, circulating pumps, expansion vessels, a pressurisation unit and a side stream filtration unit.
On the controls side, a whole new building management system was installed by Electrocom Projects consisting of:
- a new motor control center panel
- SWA’s (steel wired armoured cables)
- VFDs for all the circulating pumps.
- New primary and secondary containment.
- New TPN (three phase neutral) isolators
- Differential pressure switches across pumps
- Pressure differential switches across the pumps to allow variable flow system
- Heat meters to monitor separate circuit demand.
Moreover, the hot water system was upgraded: SPIE replaced eight 750 litre units of hot water calorifiers with six 1000 litre units and updated new cold water feed and secondary pipework. The works also included the change from an open vented to a new pressurised system. Again, this all had to be achieved without disrupting the supply to showers/basins and kitchens.
The project manager commented,
“The main benefit of starting from scratch was that it allowed us to install a new system (primary) to the boilers and then start interfacing this with the old pipework, effectively creating a hydraulically separated system and ‘re-energising’ the existing one. This is why we needed the boilers earlier than anticipated. The entire project during which we converted the heating system from open-vented to closed took us nine weeks from the start to completion.”
The existing hotel heating system was successfully upgraded while the challenge to keep the hotel running without interruption to accommodate guests was successfully met. To suit the needs of a high-rise building and restricted space, Hamworthy’s Wessex ModuMax mk3 boilers, benefitting from a high working pressure and a small footprint, were chosen.
The project manager concluded,
“Since the installation, we have noticed massive improvements in gas consumption. Where the boilers before always seemed to be at 50% or 100%, the noticeable turndown on the Wessex ModuMax boilers is amazing. After finishing the installation, we chose Hamworthy to commission our boilers because it extends the warranty and keeps it clean – I wouldn’t have it any other way. Their team is very knowledgeable about their own products and commission thoroughly. I have worked with Hamworthy for nearly 10 years across projects and have a good relationship with the sales managers. We always receive excellent support and service, before and after sales.”