The DHW distribution network is similar and parallel to the cold water distribution network, with some differences. Apart from not providing service to some consumption points that do not require hot water (toilets, urinals,...), in medium and large installations with accumulation preparation, it is necessary to use a return pipe to place the DHW as close as possible to the consumption points so that the user does not have to wait a while for the hot water to arrive. Spanish regulations require this return to be installed when the point of consumption (tap) furthest from the accumulator is 15 or more meters away.[5]​.

In this case, of centralized preparation for several homes (or several users, such as offices or premises), the existence of consumption meters is highly recommended to individualize payment and promote savings. In certain countries (Spain among them[5]​) it is mandatory to install these meters.

In the event that there has to be more than one pressure section, as many separate installations must be made (accumulation and distribution network, but not boilers) as there are sections.

With instant preparation, distribution is done with a single drive to the consumption points.

Since the preparation is often done at high temperatures (normally around 60 °C and when it comes to "cleaning" the system of legionella, it must go up to 70 °C), it is mandatory to use taps with a single outlet spout for cold water and hot water (mixer taps), so that the water coming out is at a temperature suitable for use (between 30 and 45 °C).

Virtually all types of energy can be used for accumulation preparation: electricity, diesel, natural gas, liquefied petroleum gases (LPG: butane and propane), etc. For "instant" preparation, gases (piped natural and LPG) are preferably used and, rarely, diesel or electricity.

Increasingly, due to its lower environmental impact and the foreseeable medium-term depletion of reserves of fossil fuels such as oil (and, in practice, new national regulations that require that at least part of the DHW of new buildings be obtained from renewable energies), domestic hot water is obtained through solar thermal energy, geothermal energy or waste heat, which must necessarily be prepared by accumulation.

In recent years, aerothermal has been consolidated as an efficient and sustainable technology for the production of domestic hot water (DHW), especially in the context of the decarbonization of the European residential stock. This technology, based on air-water heat pumps, allows the thermal energy contained in the outside air to be captured to heat water for domestic consumption, significantly reducing the use of fossil fuels.[6]​.

The energy efficiency of aerothermal systems is usually expressed through indicators such as the COP (Coefficient of Performance) or the SCOP (Seasonal Coefficient of Performance). These devices can achieve efficiencies greater than 4, which implies that for every kilowatt hour (kWh) of electricity consumed, they deliver more than 4 kWh of thermal energy.[7]​.

The implementation of an aerothermal system for DHW can reduce non-renewable primary energy consumption by 60% and reduce CO₂ emissions by up to 75% compared to conventional diesel or gas systems.[8]​ Furthermore, its use is compatible with both new construction installations and rehabilitation projects, and can be complemented with thermal or photovoltaic solar energy to increase energy savings.

A possible problem with the use of ACS is legionellosis. The Legionella bacteria proliferate in water with a certain degree of dirt (oxides, which come from the installation, and organic matter, from the network itself). Legionella proliferates in water at temperatures between 20 °C and 50 °C, with optimal development between 35 °C and 45 °C. Below 20 °C[9]​ it remains dormant, without multiplying, and does not survive above 60 °C. It reaches humans when they come into contact with contaminated water - showers, taps, fountains, aerosols (water sprayed into air), etc. -, through breathing. That is, a situation that almost always occurs in the shower, which is why in different countries there is legislation or regulations to prevent it.[10]​[11]​.

The DHW distribution network is similar and parallel to the cold water distribution network, with some differences. Apart from not providing service to some consumption points that do not require hot water (toilets, urinals,...), in medium and large installations with accumulation preparation, it is necessary to use a return pipe to place the DHW as close as possible to the consumption points so that the user does not have to wait a while for the hot water to arrive. Spanish regulations require this return to be installed when the point of consumption (tap) furthest from the accumulator is 15 or more meters away.[5]​.

In this case, of centralized preparation for several homes (or several users, such as offices or premises), the existence of consumption meters is highly recommended to individualize payment and promote savings. In certain countries (Spain among them[5]​) it is mandatory to install these meters.

In the event that there has to be more than one pressure section, as many separate installations must be made (accumulation and distribution network, but not boilers) as there are sections.

With instant preparation, distribution is done with a single drive to the consumption points.

Since the preparation is often done at high temperatures (normally around 60 °C and when it comes to "cleaning" the system of legionella, it must go up to 70 °C), it is mandatory to use taps with a single outlet spout for cold water and hot water (mixer taps), so that the water coming out is at a temperature suitable for use (between 30 and 45 °C).

Virtually all types of energy can be used for accumulation preparation: electricity, diesel, natural gas, liquefied petroleum gases (LPG: butane and propane), etc. For "instant" preparation, gases (piped natural and LPG) are preferably used and, rarely, diesel or electricity.

Increasingly, due to its lower environmental impact and the foreseeable medium-term depletion of reserves of fossil fuels such as oil (and, in practice, new national regulations that require that at least part of the DHW of new buildings be obtained from renewable energies), domestic hot water is obtained through solar thermal energy, geothermal energy or waste heat, which must necessarily be prepared by accumulation.

In recent years, aerothermal has been consolidated as an efficient and sustainable technology for the production of domestic hot water (DHW), especially in the context of the decarbonization of the European residential stock. This technology, based on air-water heat pumps, allows the thermal energy contained in the outside air to be captured to heat water for domestic consumption, significantly reducing the use of fossil fuels.[6]​.

The energy efficiency of aerothermal systems is usually expressed through indicators such as the COP (Coefficient of Performance) or the SCOP (Seasonal Coefficient of Performance). These devices can achieve efficiencies greater than 4, which implies that for every kilowatt hour (kWh) of electricity consumed, they deliver more than 4 kWh of thermal energy.[7]​.

The implementation of an aerothermal system for DHW can reduce non-renewable primary energy consumption by 60% and reduce CO₂ emissions by up to 75% compared to conventional diesel or gas systems.[8]​ Furthermore, its use is compatible with both new construction installations and rehabilitation projects, and can be complemented with thermal or photovoltaic solar energy to increase energy savings.

A possible problem with the use of ACS is legionellosis. The Legionella bacteria proliferate in water with a certain degree of dirt (oxides, which come from the installation, and organic matter, from the network itself). Legionella proliferates in water at temperatures between 20 °C and 50 °C, with optimal development between 35 °C and 45 °C. Below 20 °C[9]​ it remains dormant, without multiplying, and does not survive above 60 °C. It reaches humans when they come into contact with contaminated water - showers, taps, fountains, aerosols (water sprayed into air), etc. -, through breathing. That is, a situation that almost always occurs in the shower, which is why in different countries there is legislation or regulations to prevent it.[10]​[11]​.