New Drinking-Water Circulation Pump for Detached Houses
With the new drinking-water ordinance which came into force in Germany in 2003 the requirements for the quality and hygiene of drinking water and for its transport within buildings have become considerably more stringent.
The new drinking-water circulation pump Wilo-Star-Z 15 TT has an integrated timer, a temperature controller and a function for detection and support of thermal disinfection procedures executed by the boiler (photo: Wilo AG, Dortmund).
This, in turn, makes it even more important to use a circulation pump which ensures trouble-free circulation at the correct temperature. The drinking-water circulation pump Wilo-Star-Z 15 TT ensures that hot water is immediately available at each outlet in the house. In addition, it is equipped with a timer, a thermostat and a function for detecting the thermal disinfection of the hot-water system, and thus exceeds the requirements of the drinking-water ordinance.
For hygienic operation of a drinking-water heating system, the temperature at each outlet must be at least 60 °C, and operating temperatures of less than 50 °C should be avoided at all costs. In circulation systems, the water temperature in the system must never drop more than 5 K below the temperature at the boiler outlet. This is guaranteed by the thermostat of the circulation pump Star-Z 15 TT: the temperature controller keeps the temperature of the water returning from the circulation system constant at the correct, pre-set value.
Legionella bacteria multiply best at temperatures between 25 and 45 °C. They are killed by temperatures above 50 °C. For reasons of hygiene, the system should be operated so that the water temperature at any point in the system never drops below 55 °C for long periods. With its function for detection and support of thermal disinfection procedures, the wet-running pump Star-Z 15 TT provides additional protection.
For thermal disinfection, the boiler temperature is increased once per week to about 70 °C. Since this is done at night when the circulation pump is possibly switched off, the detection function is needed to detect this higher temperature and to activate on the pump even if it is switched off by the timer. This ensures that the water in the pipes is also thermally disinfected, in addition to that in the boiler.
The new timer permits three running periods per day to be programmed, thus saving even more energy. The blockage-protection function ensures that the pump cannot be blocked by deposits of lime. When the Star-Z 15 TT is switched off by the timer, the protection function automatically switches it on for ten seconds at intervals of 60 minutes in order to prevent lime deposits from building up.
The circulation pump can be connected quickly and easily with the aid of spring clamps. The materials selected by Wilo for the pump components make the pump extremely resistant to wear. The impellers in the brass body of the pump are made of the very hard-wearing material Noryl. Simultaneously with the Star-Z 15 TT, Wilo has introduced an upgraded standard Star-Z 15 with a new design and also with spring-clamp mounting. Furthermore, the entire series of circulation pumps is equipped with an insulating shell.
Source: WILO SE