Successful Cases
Case A
A Hotel with around 600 rooms, which is located in Hong Kong Island, replaced its gas-fired hot water boilers with HEC’s recommended hybrid heat pump and electric heater system in 2002. Its achievement is quoted as below:
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Energy saving
The monthly average MJ energy consumption of the new hybrid system is 60% less than that of the original gas boiler system. Moreover, the water-to-water heat pumps extract heat from the returned chilled water and lower its temperature from 12°C to 8°C. Thus, additional energy is saved from this cooling load.
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Environmental benefits
The new hybrid system improves the air quality of the hotel nearby vicinity. After removal of the chimney, the outside walls of hotel is no longer darkened by the flue gas. By using the returned chilled water as the heating source, the water-to-water heat pumps also reduce the workload of the A/C plant and thus extend its equipment life.
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Reliability
The new hybrid system has recorded 100% availability and fully met with the hotel’s requirement on hot water since its operation. At an extremely low air temperature of 7°C in winter, the heat pumps operated un-interruptibly with high efficiency. The system has incorporated a multiple level fail-safe design. It is divided into modules with totally 8 heat pumps and 4 electric flow heaters, each of these equipment acts as a backup for another.
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Space-saving
The heat pumps and the electric flow heaters are small, compact and of modular design. Since fresh air supply and flue gas exhaust systems are not required, these electrical equipment are decentralized near the loading points. Additional space is allowed inside the plant room after re-arrangement of the equipment layout and elimination of gas ancillary equipment.
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Maintenance
Since the hybrid system is relatively simple, clean and no bulk ancillary equipment is required, the annual maintenance fee quoted by the supplier is relatively low.
Case B
A hotel with nearly 800 rooms located in Hong Kong Island had been using diesel boilers to produce steam for its central hot water supply, space heating, steam-heated kitchen equipment and laundry plant since its operation for more than 30 years. To counteract the roaring oil price, this hotel adopted our proposal to replace the diesel boilers in the following sequence:-
- In 2006, the hotel installed totally 1,000 kW heating capacity water-to-water heat pumps for central hot water supply as well as relieving the existing air-conditioning loads.
- In 2007, the hotel replaced all the existing central steam-heated kitchen equipment in all the restaurant outlets by electric kitchen equipment such as steam cabinets, tilting pans & soup boilers. All the central steam heated laundry equipment was also replaced by de-centralised electric equipment.
- In 2008, the hotel dismantled the diesel boilers and installed immersed type water heaters in all the existing water storage tanks for space heating and as back-up for the central hot water supply.
The hotel operators are satisfied with the performance of our proposed electric equipment and no interruption to the hotel services had been incurred during the whole project implementation. They are proud that their hotel no longer produces pollutants and is named one of the green hotels in the industry.