DE20205210U1 - mixer tap - Google Patents

Description

i J ·*;* * · ;■ ·*■**·■;■ *: * Dr. J. Beckman

**Antfe*r Nursery 23, 57462 Olpe

16.03.2002

Mixer tap

The present invention relates to a mixer tap for cold water and hot water, a shut-off valve for a mixer tap, a system for supplying a mixer tap and a method for removing hot water. The invention is explained below by way of example with reference to Figures 1 and 2, but without being restricted to the specific features shown there.

In many residential buildings, water taps are supplied with cold water and hot water by means of a central hot water preparation WWB. According to Figure 1, the drinking water TW taken from the public drinking water network is divided into a cold water branch and a hot water branch with the interposition of a backflow preventer R and other fittings (not shown), which are each routed parallel to the taps MB. The hot water branch runs through the hot water preparation WWB, which is usually a heat exchanger supplied with heat from the central heating system, and is heated there to a higher temperature. At the tap, the hot water line WWL and the cold water line KWL come together in the mixing valve MV in a mixer tap MB. This allows water to be taken from both branches in an adjustable cold water: hot water mixing ratio of 0:1 to 1:0.

Due to the often large distance between the central hot water preparation WWB and the tap, the problem arises that the water in the hot water pipe WWL cools down. When the hot water outlet in the mixing valve MV is opened, hot water is not immediately available; instead, the water in the hot water pipe WWL must first drain away. This amount of water, which is typically in the order of 0.5 to 2 l, is usually lost unused. If several such withdrawals are made daily, this means a considerable loss of valuable drinking water.

To overcome this disadvantage and to ensure that warm water is drawn from the hot water pipe WWL as directly as possible, it is known to lay a circulation pipe parallel to the hot water pipe, which leads from a point near the (farthest) tap back to the hot water preparation WWB and in which the water can circulate under the influence of gravity or with the help of a pump. However, this method requires increased effort for the double pipe laying. If there is continuous circulation of the warm water in the hot water pipe WWL, there is a considerable loss of thermal energy. If, on the other hand, a pump controlled by a timer is used to force circulation only occasionally, this has the disadvantage that it can only counteract hot water withdrawals that take place regularly at fixed times. In many cases, therefore, the withdrawal will take place without the pump having been activated beforehand or, conversely, the pump will be activated without subsequent withdrawal.

Furthermore, it is known from the documents DE 195 18 910 C1, DE 197 20 235 A1, DE 199 34 786 A1, US 2 842 155, US 1 108 550 and US 1 247 347 to connect the hot water pipe with the cold water pipe in order to return cooled hot water. However, these systems are relatively complex.

Against this background, the object of the present invention was to avoid the disadvantages of the prior art and to enable a simpler system for rapid extraction of warm water from a tap with minimized energy and water losses.

This object is solved by the features of claims 1 and 4. Advantageous embodiments are contained in the subclaims.

According to the invention, the mixer tap MB is designed in such a way that it allows the creation of a flow connection between the cold water line KWL and the hot water line WWL when the outlet is closed, wherein the outlet is closed by a shut-off valve (ÖV2) for the outlet arranged downstream of the mixing valve (MV) (Figure 2).

According to a first embodiment, shown schematically in Figure 1, a connecting line SH ("shunt") between the cold water line KWL and the hot water line WWL is provided in front of the mixing valve MV, which can be a known single-lever mixer, for example, and in which there is a normally closed shut-off valve ÖV1. The shut-off valve is also referred to below as the "eco valve" ÖV1, as it performs a water and energy-saving function.

Before warm water is drawn from the mixing valve MV, the eco valve ÖV1 is opened. Provided that there is a higher pressure in the hot water line WWL than in the cold water line KWL, (cold) water then flows from the hot water line WWL into the cold water line KWL. This water is therefore not lost unused, but is stored in the cold water line KWL. As soon as all the cooled water from the hot water line WWL has been transferred to the cold water line KWL and water of a sufficiently high temperature from the hot water preparation WWB has flowed to the tap, the eco valve ÖV1 is closed again and the drawing of (actually) warm water can begin.

The described procedure has the advantages that

• no cold water is lost from the hot water pipe;

• there is no need to keep warm water in the hot water pipe at all times, thus avoiding energy losses;

• no double piping is required for a circulation line.

The eco valve ÖV1 can be designed as a separate actuating element ("eco button") on the fitting of the MB mixer tap. It is also conceivable to integrate the actuation into a single-lever mixer, for example by pressing the lever against the left stop to actuate the eco valve ÖV1.

In the simplest case, the eco valve ÖV1 can remain open until the user closes it or until he stops pressing a button.

Preferably, however, the eco valve ÖV1 contains a mechanism (as is known in principle from water taps in public sanitary facilities, for example) that automatically closes the eco valve after a certain time has elapsed since it was opened. The time constant of the mechanism should be adjustable so that it can be set individually for each tap to the time that is needed for the cooled water to flow out of the hot water pipe WWL.

It is also possible for the eco valve ÖV1 to be coupled to a temperature sensor that measures the temperature of the water flowing in the hot water pipe WWL. As soon as this temperature sensor measures a preset temperature after the eco valve is opened, which indicates that the water in the hot water pipe WWL is sufficiently warm, the eco valve ÖV1 can close. In a special design of this temperature-controlled eco valve ÖV1, for example, when the eco valve ÖV1 is operated, a spring-loaded mechanism could engage in the open position on a latch, with the latch being retracted by a bimetal element and causing the eco valve ÖV1 to return to the closed position when the temperature of the flowing water exceeds an adjustable threshold.

Figure 2 shows an inventive design of a mixer tap MB. No separate connecting line is provided between the cold water line KWL and the hot water line WWL, but only the outlet is provided with a shut-off valve or "eco valve" ÖV2. If this normally open eco valve ÖV2 is closed and the valves VWW for hot water and VKW for cold water are opened, cooled water under higher pressure can flow from the hot water line WWL into the cold water line KWL. The function is therefore the same as in the system according to Figure 1, although the

"Short circuit" of the lines occurs by closing the eco valve ÖV2 and simultaneously opening the mixing valve.

The normally open eco valve ÖV2 can be designed in a similar way to the normally closed eco valve ÖV1 with a time and/or temperature dependent return to the initial state, whereby only the states "closed" and "open" behave in a mirror image. The advantage of the system according to Figure 2 is that the eco valve ÖV2 can be easily retrofitted to existing systems by screwing it onto the outlet of a mixer tap MB.

The flow of water from the hot water pipe WWL to the cold water pipe KWL requires that there is a correspondingly higher pressure in the hot water pipe WWL than in the cold water pipe KWL. If this is not already the case, this must be ensured by suitable means of generating a pressure difference.

One possible way to do this is to install a pump P (similar to the well-known circulation pump) in the hot water pipe WWL, which increases the pressure between its inlet and outlet sides. The pump can also be connected to a pressure sensor in the cold water pipe KWL in order to be able to maintain the desired pressure difference at all times by comparing it with the pressure present there.

Alternatively or additionally, a pressure reducer DM can be installed in the cold water line KWL, which ensures a corresponding pressure difference to the hot water line WWL.

Claims (7)

1. Mixer tap (MB), containing: - a connection for a cold water pipe (KWL), - a connection for a hot water pipe (WWL), - a mixing valve (MV) with one outlet, characterized in that a shut-off valve (ÖV2) for the outlet is arranged downstream of the mixing valve (MV). 2. Mixer tap according to claim 1, characterized in that the shut-off valve (ÖV2) is designed such that, following an actuation, it returns to the initial state after a predetermined, preferably adjustable period of time. 3. Mixer tap according to one of claims 1 or 2, characterized in that the shut-off valve (ÖV2) contains a temperature sensor and is designed such that it returns to the initial state following an actuation when a predetermined, preferably adjustable, water temperature is present. 4. Shut-off valve (ÖV2) for a mixer tap according to at least one of claims 1 to 3, characterized in that it can be screwed onto the outlet of the mixing valve (MV). 5. System for supplying a tap with hot and cold water, comprising - a fresh water supply (TW), - a hot water pipe (WWL) leading from the fresh water supply to the tap, - a cold water pipe (KWL) leading from the fresh water supply to the tap, - a mixer tap (MB) forming the tap point, connected to the hot water pipe and the cold water pipe, characterized in that the mixer tap is designed according to at least one of claims 1 to 4, and that a pressure difference generating means (P, DM) is arranged in the hot water line and/or the cold water line, with the aid of which a higher pressure can be generated in the hot water line than in the cold water line. 6. System according to claim 5, characterized in that the pressure difference generating means comprises a pump (P) arranged in the hot water line (WWL) and preferably connected to a pressure sensor in the cold water line (KWL). 7. System according to claim 5 or 6, characterized in that the pressure difference generating means comprises a pressure reducer (DM) arranged in the cold water line (KWL).