Design standards for water supply and drainage and selection of heating methods for hotel swimming pools
I am Daniel Wang, a water supply and drainage specialist. The water supply and drainage design and the selection of heating methods for hotel swimming pools are key aspects of a hotel's water supply and drainage system that involve a high level of technical content and have a significant impact on operating costs. They directly affect swimmers' comfort experience, water quality safety, and the hotel's energy consumption control. Based on my years of experience participating in five-star hotel and resort projects, this part of the design must strictly comply with national standards while also taking into account energy savings and operational and maintenance convenience.
First, regarding water supply and drainage design standards, the core basis is the Standard for Design of Building Water Supply and Drainage GB 50015-2019 and the Technical Specification for Water Supply and Drainage Engineering of Swimming Pool CJJ 122-2017. Specific key points include:
- **Circulation and filtration**: Hotel swimming pools must adopt a circulating purification water supply system and must not use a once-through system. The circulation period is generally designed at 4-6 hours (GB 50015-2019 Article 4.9.9) to ensure water quality. For example, for a 500 m³ indoor pool, the circulation flow rate must reach 125 m³/h or more. In one resort hotel project, because sufficient space for the circulation pump room was not reserved, later renovation became difficult, so at the initial design stage it is necessary to ensure that the machine room area meets the equipment layout requirements.
- **Drainage and reuse**: A drain pipe should be provided for emptying the pool water, discharging directly into the rainwater or sewage system, but environmental protection requirements must be noted; some regions require disinfection before discharge into sewage. For the overflow return water system, the counterflow type (water inlet at the pool bottom, overflow return at the pool wall) should be given priority, as it can effectively remove floating dust on the surface. According to CJJ 122-2017 Article 6.3.1, the volume of the balance tank or equalizing tank should meet the needs of circulation pump operation and overflow return water.
- **Water quality standards**: Hotel pool water quality must comply with the Hygienic Standard for Swimming Places GB 37488-2019, with residual chlorine controlled at 0.3-1.0 mg/L and pH at 7.0-7.8. For disinfection, it is recommended to use chlorine disinfection combined with ultraviolet or ozone assistance to reduce chlorine odor and improve water quality. In an international brand hotel project, I adopted a sodium hypochlorite generator + medium-pressure ultraviolet system, and operational feedback was good, while also reducing the risk of chemical transport.
Second, regarding the selection of heating methods, this mainly depends on the hotel's heat source conditions, pool scale, and operating strategy. Common methods include:
- **Gas-fired hot water boiler + plate heat exchanger**: This is the most mature and fastest-responding method, suitable for hotels with a gas supply. The heat load is designed based on initial pool water heating (temperature rise within 24-48 hours) and daily constant temperature maintenance (maintaining 26-28℃). According to GB 50015-2019 Article 4.9.16, heating equipment should be provided with automatic temperature control. For example, an urban business hotel selected two 1.05 MW gas boilers, one duty and one standby, to heat pool water through plate heat exchangers; the winter constant temperature was stable, but operating costs were slightly higher.
- **Air-source heat pump**: Suitable for regions with a mild climate, with significant energy-saving effects, and a coefficient of performance (COP) of 3.0-4.0. However, attention should be paid to performance degradation in low-temperature environments, and it is recommended to combine it with auxiliary electric heating. In a southern resort hotel project I participated in, two 130 kW air-source heat pumps were used together with solar preheating, saving about 40% of electricity annually, but the initial investment was relatively high.
- **Solar energy + auxiliary heat source**: Suitable for regions with abundant sunshine and can greatly reduce operating costs. However, a heat storage tank must be provided, along with a gas boiler or electric heating as auxiliary. According to the Technical Standard for Solar Heating Engineering GB 50495-2019, the collector area must be calculated based on local solar irradiation. A seaside hotel used rooftop solar collectors combined with pool water insulation, so basically no auxiliary heating was needed in summer, but in winter a gas boiler was still needed for supplementary heating.
- **Electric heating**: Only suitable for small pools or temporary heating, and not recommended as the main heat source because of its high operating costs and large electrical load.
Practical case: In a five-star resort hotel, we adopted a combined "gas boiler + air-source heat pump" scheme: daily constant temperature was handled by the heat pump, while initial heating and extreme weather were supplemented by the boiler. At the same time, a plate heat exchanger was designed to interlock with the pool water circulation system, and a constant-temperature control valve was installed. Operating data showed that, compared with a single-boiler scheme, annual energy consumption was reduced by about 35%.
Summary: Hotel swimming pool water supply and drainage design must strictly comply with GB 50015-2019 and CJJ 122-2017, with emphasis on ensuring circulation filtration, water quality safety, and drainage compliance; the heating method should be based on the hotel's heat source conditions, climate, and operating costs, giving priority to efficient and energy-saving schemes such as heat pumps or solar-assisted heating. Reasonable design can significantly improve swimmers' experience and reduce long-term operation and maintenance costs.
The above are reference opinions. The actual situation of the project still needs to be further comprehensively evaluated and implemented in combination with specific working conditions, site conditions, and other factors.