Tuesday, 7 March 2017

Carl Turbitt, ABB's UK HVAC drives team leader, writes: When you’re staying at a hotel and run the taps for a bath, or turn on the shower, or even pour a drink or brush your teeth, how often do you think about the system of pumps and pipes throughout the building that ensure the right amount of water is available in the right place at the right pressure and temperature whenever it is needed? The answer is probably not a lot, but then why should you?

As with many things, clean running water is something that it’s easy to take for granted. However, when it’s not there, or not functioning as it should, it becomes impossible to ignore.

Demand for water within a hotel can vary greatly throughout the course of a day, as guests take their morning showers and evening baths. There are also the needs of the hotel to consider, with water required by the kitchen, as well as amenities such as spas and swimming pools. For paying guests, anything less than 100 percent uptime is unacceptable, which is why it’s so important that a hotel’s water supply system is carefully designed and well looked after. Pumps are critical components in these systems, and take much of the strain in ensuring water is available whenever it’s needed.

Which is why, when Britannia Hotels acquired a hotel with a failing hot water system, it knew it needed to act quickly to rectify the situation. Problems included intermittent changes in water pressure, banging noises in the pipes and, on occasion, a complete breakdown that left staff and guests without any hot water.

The hotel turned to PressBoost, which installs and maintains the pump systems in all Britannia Hotels. Examination of the system revealed three large pumps operating in a duty-standby-standby configuration. Although the pumps were large enough to provide more than enough hot water to meet the needs of its hotel and its guests, the lead pump was doing all of the work, causing it to regularly fail. The system was also highly inefficient, as the motors driving the pumps had no speed control. This meant they ran at full speed all the time regardless of the actual level of demand, resulting in heaps of wasted energy.

This case was an example of how a variable speed drive (VSD) can help. VSDs were installed on each of the three pumps and the configuration was changed to duty-assist-standby. The drives adjust the speed of the pumps depending on the level of demand. When less hot water is required, the flow of energy from the motor to the pump is reduced. This has enabled the hotel to cut the energy it uses to supply hot water by a massive 53 percent.

The VSDs have also helped to improve the reliability of the hot water supply by keeping water pressure constant at 3.5 bar. Before the drives were installed, water pressure fluctuated between 3 and 6 bar, causing water to ‘hammer’ in the pipes. This put additional stress on the pipework, bearings and seals, which contributed to the reliability issues the hotel was experiencing.

The hotel’s guests are now enjoying a reliable water supply, whether they’re having a washing, bathing or even swimming in it. Meanwhile, the hotel itself can look forward to lower maintenance costs and more satisfied guests.

To read the full story, click here.

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