DE10049597A1 - Control device for switching pumps in hot water circuits with heat exchanger, switches circulating pump based on rate of change of temperature - Google Patents

Abstract

Temperature sensors measure the temperature increase near to the heat exchanger when hot water is drawn. Based on the rate of change of temperature, an electronic evaluation device detects the drawing of hot water and switches the circulating pump for a set time, as demand requires, to convey hot water quickly and with low electrical energy or heat loss to the draw point.

Description

In a large number of buildings, hot water is provided by a heat exchanger ( 1 ), a circulation pump ( 2 ) and a pipeline laid as a closed ring.

However, since the warm water cools in the generally long water pipes, the circulating pump ( 2 ) transports the hot water during the main periods of use. The longer the pump runs, the longer the heat losses occur. If the circulation pump is not running, a large amount of cold water must first drain off before the warm water runs out of the valve. This significantly increases water and heating energy consumption. In addition, the waiting time until the warm water from the hot water valve runs is often long.

The following invention enables the demand-dependent connection of the Circulation pump and thus saves heating energy and water. It will be above all It is important that an intervention in the piping system is avoided by existing systems to avoid expensive plumbing.

The device is intended to enable the layperson to retrofit old systems by one to enable wide application.

The basis of the invention is that in hot water network pipes the enclosed hot water slowly cools down and does not heat up or heats up very slowly when the water is heated by the heat exchanger ( 1 ).

When hot water is drawn off, the warm water enters the beginning of the hot water pipeline network and causes a steep rise in temperature, which is otherwise not achieved by any other process. A rapid rise in temperature at the starting point of the pipeline network can thus be taken as evidence of a consumption of hot water, which in turn leads to the circulation pump ( 2 ) being switched on.

A corresponding arrangement is shown in FIG. 1.

For example, when the nozzle valves ( 4 , 5 ) are opened, the hot water will come out of the heat exchanger ( 1 ) and the temperature sensor ( 3 ) will heat up very quickly. Due to this temperature rise, the microcomputer ( 7 ) recognizes that hot water is being drawn off and switches on the circulation pump ( 2 ), which quickly transports the water to the tap.

In order to quickly identify the tapping of hot water, the temperature sensor ( 3 ) must be installed as close as possible to the heat exchanger ( 1 ).

Of course, the cheapest way is to install the sensor in the water circuit at a fast rate Enable response times. But since this is not easy for laypeople, it is also possible to use a contact temperature sensor which  Measures surface temperature of pipes. These sensors can also be used Plastic pipes are used.

As shown in the example, a computer ( 7 ) with analog-digital converter ( 6 ) can be used as the evaluation device, which detects the temperature change on the sensor or sensors and switches on the pump ( 2 ) if the water temperature rises rapidly and positively.

The pump must be switched on at least so long that the water is one complete circulation through the pipe system.

Then the pump remains blocked until the hot water is on the or Has cooled temperature sensors by an amount that can be entered. Another tap can now be demonstrated again by a rapid rise in temperature.

If a computer ( 7 ) with self-learning properties is used, it will "notice" that hot water is always drawn off at certain times. The computer ( 7 ) now switches on the circulation pump ( 2 ) for a short time before the usual times of use in order to make hot water available at the taps in advance. If hot water is then actually tapped, the hot water pushes the somewhat cooled water out of the heat exchanger to the sensor ( 3 ). This causes the temperature on the sensor to rise, which is recognized in the computer as a sign of water withdrawal. This is recorded in the computer and leads to pumping at the same time the next day.

The easiest way is z. B. assigned a memory location in the computer every quarter of an hour. Depending on whether hot water is used or not, the time cell of this corresponding quarter of an hour is increased or decreased by one. A change in the usage times is followed by an automatic change in the switching times of the pump ( 2 ).

To increase the reliability of the evaluation, a second temperature sensor ( 8 ) can be installed at a defined distance (e.g. one meter) from the first sensor. When tapping warm water, the first sensor and then the second sensor will report a warming. With the same sensor and the same pipe material, the flow rate can be determined as a side effect in order to monitor the function of the pump and detect blockages in the pipe.

A water meter can also be used as a sensor for water extraction, which outputs counting impulses to the microcomputer when water is drawn.

If an additional temperature sensor ( 9 ) is installed on the return of the heat exchanger, you can see when there is water with a minimum temperature in the entire pipe network after switching on the pump ( 2 ) and can therefore switch off the pump at an optimal time.

After installing the control unit, the computer becomes the system-typical Time constants (dead time after switching on the pump until the temperature rises on Sensor enters, time constant temperature sensor in connection with the pipeline etc.) and save them as tax criteria.

Legend

1

Heat exchanger with storage

2

circulating pump

3

temperature sensor

4

Outlet valve (hot water tap)

5

Outlet valve (hot water tap)

6

Analog to digital converter

7

computer

8th

temperature sensor

9

Temperature sensor on the return of the heat exchanger

Claims (5)

1.Control device for the demand-dependent switching of pumps in hot water circuits with heat exchangers, characterized in that the temperature rise when tapping hot water is measured by means of temperature sensors on the hot water connections or near the heat exchanger and, based on the rate of change in temperature, an electronic evaluation device taps the tap detects hot water and then the circulation pump switches for an adjustable time in order to transport hot water quickly and with little loss of electrical energy and heat to the tap as required. 2. The computer before the usual tap times of hot water the circulation pump switches on by notifying this event each time hot water consumption is detected saved together with the time and thus frequency tables for the Hot water consumption created, which in turn is used to provide hot water the usual tapping times by switching on the pump. 3. The water temperature is measured at the return of the heat exchanger and thus it is recognized when hot water with a The minimum temperature is around the pump at an optimal time switch off and thus save energy. 4. That with the help of at least two temperature sensors with a defined distance Flow rate of hot water can be determined. 5. Using a calculator, each tap of water in a timed order Directory is noted so that due to the frequency of hot water withdrawal can be inferred at the time of day about the consumption habits and thus the Pump is switched on before the water is drawn off.