First, most Chinese university dorms don't have any central heating systems or air-conditioning units.

首先，大多数中国大学宿舍没有任何中央暖气系统或空调设施。

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The heat transfer between residential units is a difficult technical problem in heat metering of central heating systems.

户间传热是集中供暖热计量中的一个技术难题。

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Due to their simplicity, fan coil units are more economical to install than ducted or central heating systems with air handling units.

由于其简单，安装风机盘管机组更经济比导管或中央供暖系统空气处理单元。

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We are wasting millions, contributing more to global warming than industry, letting pensioners get cold despite free central heating systems they can't afford to switch on, and letting kids get asthma in damp cold bedrooms and overheated classrooms.

BBC: The ?1,000-a-year heating bill is here.

Heating and cooling experts say central air-conditioning systems should be serviced annually to remove dirt, change filters and check the level of Freon, a refrigerant.

WSJ: Don't Wait to Service AC Units