Domestic hot water was formerly supplied by LTHW boilers and storage calorifiers with the stored water supply serving an on-site restaurant. However, since full restaurant facilities are no longer provided, there is reduced demand for hot water and it was decided to separate the heating and water heating functions so that the boiler plant can be shut down in the summer months in order to save energy.
In a very tight schedule, all the original plant and pipework was stripped out and replaced, the project being completed in time for the start of the 2008/9 heating season. Wolverhampton City Council Facilities Department expects that the newly designed heating and water heating system will deliver energy savings in the region of 15%. In addition, Wolverhampton City Council has incorporated a chlorine dioxide dosing system into the DHWS, as part of their water hygiene regime. This has enabled them to lower the water temperature to 450C, which has reduced the carbon footprint of the building still further.
The new heating and ventilation system was designed by Jacobs consulting engineers and they were responsible for specifying the Andrews MAXXflo storage water heaters. These were selected for their high efficiency, condensing capability and high recovery rate as well as their compact footprint and aesthetic appearance. Another important consideration was their modular burners, which not only provide flexibility in the provision of hot water but are also simpler to maintain as individual burners may be serviced while others are still in operation.
Domestic hot water supplied by the MAXXflo heaters serves the catering facilities which mainly offer a cold buffet and sandwiches, hence the reduced requirement for hot water in the building. The other draw off points are in the 34 staff toilet facilities located throughout the building, as well as disabled and private toilets. Each staff toilet has up to seven wash hand basins and a cleaner’s cupboard with a Belfast sink.
The MAXXflo water heaters were installed by SG Maintenance Services in the basement boiler room, connected to standard open flues. A spokesman for the installer commented: “We were very happy with the level of customer support provided by Andrews Water Heaters and the technical assistance we received from their Area Sales Manager”
The MAXXflo CWH 90/300 models selected feature a fast recovery time which is ideal for use in public buildings as this ensures that hot water provision is always reliable, despite peaks in demand. Each unit has a storage capacity of 300 litres, an output from 19.5 kW to 91.6 kW and a recovery rate of 1530 litres/hour through a temperature rise of 50oC.
These high efficiency water heaters incorporate stainless steel heat exchangers and tank and fully modulating premix burners to provide maximum performance flexibility with economic running costs. Generating hot water in condensing mode up to 80% of the tank volume, condensing technology allows them to operate at 109% efficiency. Heat input and flow are carefully regulated to produce a closely controlled water temperature and a high temperature anti-legionella program is incorporated as standard. These units are robustly constructed from stainless steel giving a long service life and, for maximum energy savings and operational convenience, they are connected to the on-site Building Energy Management System.
Winner of the Queen’s Award for Innovation, the MAXXflo range of condensing storage water heaters has integral tank options of 200 and 300 litres capacity, each with four output sizes from 30 to 120kW. MAXXflo units have a small footprint and offer flexible flue options for ease of siting.