The water temperature used for showering is usually 37-40°C . This temperature goes down by only 3 degrees before the water reaches the sewage system. Thus, about 90% of the energy used for water heating is uselessly wasted in the drain (assuming the temperature of the incoming tap water is about 10 oC).
A special shower water heat exchanger included in the drainage system can significantly lower these high energy losses, almost up to the level of approximately 50%. Due to this, up to 45% of the water heating costs can be saved.
The main part, also called the active part, of the heat exchanger body is made of with pressure profiled stainless steel plates AISI 316, soldered in a vacuum oven with 99% Cu. Warm waste water freely runs along the surface of profile. Fresh cold water from the water supply pipe goes through the inner part of the the stainless plates. Cold water recovers part of the thermal energy of the warm used water going out to the sewer along the outer profiles surfaces. Thus, incoming fresh water can be preheated up to 20-22°C and comes then to the cold water tap of the shower. The temperature of the drained water stream is lowered by 12-15°C. Preheated “cold water“ in the shower tap is mixed with the hot water coming from the standard boiler. The volume of the conventionally heated water is reasonably lowered.
Additional savings can then be achieved by using a smaller water heating device, a smaller hot water reservoir or a lower number of sun collectors, if used.
Heat-exchanger installation can be considered both for reconstructions of existing bathrooms and in new buildings. The accessibility to bathroom drainage and fresh water piping is a basic condition for heat-exchanger installations. In accordance with the space requirements heat exchangers can be placed/installed directly under the shower place or suitably anywhere near the shower, but in any case in a horizontal position and as close to shower drain as possible, in order to obtain the most efficiënt use of the heat exchanger system. The possible space for exchanger installations is also the ceiling in the room under the shower.
The connecion on the side of waste water is the standard plastic drain piping DN40. The clean water side might be connected with a flexibe tubes which makes the installation much more easier.
Cleaning and maintenance
Clean active surfaces of the heat exchanger body are the basic condition for the highest possible efficiency of the system. However if the shower is used regularly, no extra cleaning is needed. Usual water and drain piping can be easily cleaned using standard bathroom cleaning detergents during their periodical applications when cleaning the shower siphon trap. Standard chemical or biological cleaning detergents are very efficient for these purposes. Liquid cleaning detergents are applied directly into the shower siphon trap as well as the powder type. If biological detergents are used, then skims removal is realized by bacteria which live in drain piping systems. When all organical skims on the exchanger surfaces are removed, the bacteria die and are splashed away by the shower waste water.
The cleaning process should be repeated periodically each 6 month if the shower is regularly used.
Dimensions and specifications:
Exchanger box: vacuum molded plastic (ABS) panels
Exchanger active body: stainless steel plates AISI 316
Exchanger box dimensions: 522x144x87mm.
Wate water connection: DN40.
Clean water connection: G3/4“ (G1/2″).
Weight: 1800 g. Max. operating temperature: 90°C. Max. operating pressure: 16 bar.