DE3902113C2 - Water heater for the thermal killing of Legionella - Google Patents

Description

The invention relates to a water heater for the periodic heating of the entire memory content is suitable for killing Legionella or its infection keep the number at a very low level all the time.

Legionella are bacteria that are in the water at Tempe temperatures between 31-42 ° C have their optimum growth, from 50 ° C their number decreases, then at Dying quickly at temperatures above 60 ° C. The infect man takes place exclusively via the respiratory tract by inhaling aerosols containing legionella (e.g. Shower rooms). Manifestations of the disease are Legionnaires' disease (febrile pneumonia) and Pontiac Fever that can occur epidemically. Favors through energy saving regulations the level of hot water temperatures for sanitary purposes in generally lowered in recent years. This will thermal boundary conditions for the growth of Microorga nisms in water storage improved. Countermeasures in the form of chemical exposure, e.g. B. shock chlorination, are excluded for drinking water systems.

To the growth and spread of microorganisms to prevent, procedures and facilities are ver various types of water have become known keep germ-free.

DE 38 36 523 A1 describes such a method and the device shown here, here the memory content periodically raised to temperatures above 70 ° C  is heated to kill the germs. To a good through mixture and an even temperature distribution a circulation pump is used here.

The patent DE 58 829 C shows a sterilization device direction where the water is in a pressure vessel is heated to 120 ° C, so that sterility is guaranteed.

DE 3 40 943-C describes a drinking water heater, where the water is close to the boiling point is heated and thus freed of germs and for cooling down to drinking temperature by a Cooler is guided, which acts as a heat exchanger and the incoming cold water preheats.

The patent DE 35 25 990 C2 shows a custom water heater, which ensures that in the upper area of the storage boiler, i.e. in the area in which the process water is extracted, a tempe rature of 80 ° C, so that in this area Water is largely germ-free.

Another form of a water heater shows the US-A-2 633 108 which is the water heater flowing water to about 180 ° Fahrenheit (82 ° C) is heated.

Document EP 0 270 993 A2 shows a custom water heater and a method and device to prevent the preservation and multiplication of harmful germs, taking various measures a uniform temperature is taken division of the heated water in the storage tank Afford. Once, as already mentioned above, by means of a  Circulation pump, also with a so-called external heater, where the boiler wall is mostly double-walled is designed so that the kettle contents evenly can be heated from all sides. Still is a so-called outflow at the bottom of the boiler aperture provided, which the inflowing warm Distribute water evenly in the boiler.

All of the procedures and setup described above Services for domestic water heating have a or several of the following disadvantages.

For one thing, it makes no sense to use the entire memory content heat up to 100 ° C or more as this will enormous energy consumption needed. Will the memory content to save energy only periodically heated to about 70-80 ° C, there is the disadvantage that by this brief heating up an equal moderate mixing of the water and thus a uniform temperature distribution not guaranteed is accomplished. Find in the so-called "cold zones" the bacteria still have good propagation conditions in front. Remedy against the formation of "cold zones" create various facilities through which the Memory content is mixed.

However, the mixing conditions described above sometimes drive insufficiently or with a relatively high level Associated effort. Even so-called double-jacket water heater in a standing version with heated floor show a temperature difference in the stratification up to 20 ° C. The latter is specific to the low Heating surface load and on the primary circulation direction from top to bottom.  

Other physical treatments to kill the germs, like UV radiation, oligodynamic processes still have have not reached a practical level or have others Disadvantage.

What remains for the time being is the periodic, short-term warm-up storage at temperatures around 70 ° C.

Disinfection of the downstream water circulation netzes is the subject of other innovations.  

All of these storage water heaters are due to their construction not suitable, the entire water content evenly to high tem heat up temperature. There are always certain zones not or not be sufficiently high temperature.

The invention has for its object the entire memory content heat to a uniformly high temperature. This also applies to the bottom area, especially for sediments that are deposited on it. From publications it is known that the number of germs in the Deposits 150 times that of the one above Reach water.

In addition, the floor should be easy to clean and the cold Do not fill sediment with water during cleaning.

This object is achieved by the technical teaching of claim 1. It is advantageous that for the heat transfer a specific highly loaded spiral tube heating surface ge was chosen, which - interrupted by the necessary, large dims based cleaning opening - also into the lower storage room puts.

The remaining lower volume including sediments is heated by the double floor.

Contrary to the usual flow direction of the heating medium Guided tour from bottom to top.

The cold water inlet is from the rear, the floor recess is without Connection made.

The advantages that can be achieved with the invention are in particular in that the water content of the storage tank is completely even (tem temperature gradient between the lower and upper floor 1.4-2 ° C) is heated.

A constant floor temperature over the surface is achieved by the wedge-shaped distribution chamber ( 7 ). The flow of water must pass through a cavity ( 6 ) which is formed by the tank bottom ( 5 ) and double bottom ( 4 ). The resulting flow resistance prevents direct flow to the connection ( 9 ) and favors a radial distribution in the cavity ( 6 ) (see Fig. 2).

By reversing the flow direction of the heating medium, the highest temperatures in the heat-emitting areas of the double ground up.  

When sediments are deposited, the temperature in the discharge increases struggled disproportionately. The worse compared to water Thermal conductivity reduces the heat exchange with the one above lying water until off due to increased sediment temperature done immediately.

The advantage achieved is the highest temperatures in legionella populated deposits.

An embodiment is shown in the drawings and is described in more detail.

Fig. 1 shows the water heater in a side view

Fig. 2 the details in the floor area.

You can see the three-way division of the heating surface.

The highest temperatures are given in the floor heating surface, which is formed from the tank bottom ( 5 ) and double floor ( 4 ). Heating water flows through the flow ( 10 ) into the distribution chamber ( 7 ), is distributed in a wedge shape ( Fig. 2) and continues radially in the cavity ( 6 ).

The entire lower floor is heated. The collecting chamber ( 8 ) combines the partial flows and supplies the lower tube heating surface ( 3 ) or tube heating surface ( 2 ) via the connection ( 9 ).

The cold water inlet was deliberately not placed in the lower floor area assigns to pollution of the nozzle during cleaning prevent. The floor recess is completely smooth, the access through the Cleaning opening without problems.

Is part of the water heater to kill Legionella a control that is every 2-4 days (not over 6 days) the storage tank is heated to 70 ° C.

A second thermostat is switched on by a timer, the superimposed on the normal thermostat.

An alarm monitor controls the correct heating at the set time.

Claims (4)

1. Water heater for the thermal killing of Legionella, a double floor is provided in which the loading container bottom ( 5 ) acts as a heat transfer surface and from which spiral, concentric tubular heating surfaces are guided upwards through the storage container, with the heat transfer surfaces acting from bottom to top are characterized in that the double floor ( 4 ) has two forms, which are designed as a distribution chamber ( 7 ) and a collecting chamber ( 8 ), the flow ( 10 ) opening horizontally into the distribution chamber ( 7 ) on the one hand and a narrowed gap on the other Raised bottom ( 4 ) and container bottom ( 5 ) is formed and that in the collecting chamber ( 8 ) on the one hand a narrowed gap, formed by the double bottom ( 4 ) and container bottom ( 5 ), opens and on the other hand the connection ( 9 ) of the tubular heating surface () 3 ) goes off. 2. A method of operating a water heater according to claim 1, characterized in that, starting from the wedge-shaped distributor chamber ( 7 ), the water flowing into the double floor ( 4 ) is distributed in a wedge shape over the narrowed gap and then flows radially in the cavity ( 6 ) , and that the collecting chamber ( 8 ) summarizes the partial flows flowing in the cavity ( 6 ) and forwards them via the connection ( 9 ) via the tubular heating surfaces ( 3 , 2 ). 3. Procedure for operating a water heater according to Claim 1 or 2, thereby characterized that for automatic periodic heating uses an external control that is by means of timer and high temperature thermostats as well as an integrated alarm detector which ensures germs. 4. A method of operating a water heater according to one or more of claims 1 to 3, characterized in that starting from the raised floor over the ascending spiral-shaped concentric tubular heating surfaces ( 3 , 2 ) the entire memory content ( 1 ) periodically to temperatures of 70 ° C. is heated.