CENTRAL HEATING SYSTEM AND WATER SYSTEM AND METHOD FOR CONTROLLING THE TIGHTNESS THEREOF

Abstract: In order to control the tightness of a central heating system (10, 11), the system is provided with a flow meter (8, 9) and a valve (6, 7) in the flow (3) and return pipes (4), respectively. Hereby it becomes possible to monitor the liquid flow through the flow meters (8, 9) and in a control unit (15) to compare the signals from the flow meters (8, 9). When a certain limit value is exceeded, an electric motor on the inflow flow (6) is ordered to shut off the flow of water into the system (10, 11) and a signalling device (16), if any is activated. In order to be able to control the water flow and the tightness of a water system (Fig. 3), the branch pipe (3) is connected to a motor valve (6) and a flow meter (8), before the water is led the water pipe (10) of the building. The flow meter (8) gives electrical signals to an electronic control unit (15, 18) which compares the electric signals being proportional to the water flow with the pre-determined limits, and when the flow is in excess of the upper limit and/or below the lower limit, a signal is immediately given to the motor valve (6), which will shut off the water flow in the system.

Description: CENTRAL HEATING SYSTEM AND WATER SYSTEM AND METHOD FOR CONTROLLING THE TIGHTNESS THEREOF. The invention relates to a central heating system or a similar closed heating system with inlet and outlet for a heat carrying medium, and a method for control¬ ling the tightnes of the system. Central heating systems of this type are usually ope¬ rated with water as the heat carrying medium. The wa¬ ter is either heated in a local heating plant or in a district heating plant. In such installations the heat carrying medium is common to the whole system, and such systems are called directly connected systems. By such directly connected systems there will be a risk of large amounts of water flowing out, eg. if a radiator or a pipe bursts resulting in damage to the building. This is due to the considerable quantity of water contained in a system of this type. If the water flow is not immediately shut off in that part of the system where the leak is, such damage will be very comprehensive since the water will at worst not be shut off until damage has been done, e.g. if there are no persons present. It is the object of the invention to overcome this d sadvange by these directly connected systems, and this is achieved by a system where a volume flow me¬ ter with an electric output signal is inserted at the inflow and return flow of the medium, and a motor valve for shutting off the flow through the flow me¬ ter and a non-return valve for shutting off the re¬ turn flow after the return flow meter. This enables a continuous control by supervising the flowing and returning amount of water, respectively, thus controlling the tightness of the system, be¬ cause any difference between the inflowing amount and the returning amount indicates a loss of fluid stem¬ ming from a leakage. Hereby such a leakage can be de¬ tected far away from the installation, and the water flow can be shut off at once, e.g. by actuating the motor valve, which can be electrically driven. At the same time the non-return valve will ensure that no water is led to the system through the return pipe which makes it possible effectively to prevent that no more water escapes than can be helped. This makes it possible at a very early stage of the leakage to take action and thus prevent any damage to the installation and the building. By, as referred to in claim 2, having a control unit automatically monitor the volume flow meters and sig¬ nal to the motor valve and maybe an alarm, in case the existence of a leakage has been established, an automatic shutting off of the flawed section of the plant is achieved. By means of the method referred to in claim 3, where the signal from the meter is compared with a pre-de¬ termined rate of water flow, the supply of water can be shut off effectively, whereby damage to the buil- ding or installations dependent on water, animals, plants, etc. can be avoided altogether. By, as referred to in claim 4, making the comparison within a certain time interval, even the smallest leak will be detected, if it is controlled at a time where no water consumption takes place. This will rule out the tremendous waste of water caused by small leaks, water taps that are not turned off, lea- ky ball cocks, etc. In the following the invention will be described in closer detail with reference to the drawing, in which fig. 1 shows a pipe diagram of a district heating installation, fig. 2 shows a block diagram of the control unit, and fig. 3 shows a pipe diagram of a single-pipe wa¬ ter installation. In fig. 1 is shown an example of an embodiment of a system comprising a district heating supply system 1, 2 and a central heating installation comprising ra¬ diators 11 with communication pipes 10 in a generally known manner. The district heating installation comprises a flow pipe 1 and a return pipe 2. Mounted to this installa¬ tion are the connecting pipes 3 and 4 of the central heating system. At the place 5 where the system is used, as indicated by a dotted line, an electrically driven motor valve 6 is mounted on the flow connecting pipe 3, which valve, when the motor is actuated, will limit the flow of hot water from the district heating pipe 1. After the motor valve 6 a volume flow meter 8 with electric output signal is mounted, a so-called flow meter. In the return end of the system a similar flow meter 9 and a non-return valve 7 are mounted shutting off the water from the return pipe 2 of the district hea¬ ting system. In a generally known manner the system comprises a number of radiators or heat exchangers 11 since it is within the scope of the invention to mount flow me¬ ters and valves at any required place of a central heating system, where it is desirable to control the tightness of the intermediate section of the instal¬ lation. Fig. 2 shows an example of a control unit 15 for car- rying out the method for controlling the system shown in fig. 1. The flow meters 8, 9 give an electrical signal which is proportional to the amounts of water passing through the flow meters. These signals 8, 9 are transmitted to counters 12, 13, which then record the amount of flowing and returning water, respectively, of the system. The signals are supplied to a comparison circuit 14 which will show whether there are any disparities above a certain limit between the two signals; if this limit is exceeded, it means that there is a leak in the intermediate sections 10, 11 of the sys¬ tem. Moreover, a counter control can take place, i.e. an indication as to whether the flow meters work accord- ing to their specifications. Should a disparity be recorded between the two coun¬ ter values, a signal is produced to the motor of the motor valve 6, which is immediately actuated and shuts off the supply of water into the system. Moreover, a signal can be given to a visual or audi¬ tive alarm 16. In the comparator 14 a unit is incorporated for re¬ jection of the results measured at a slow flow. If this cancelling of the measuring signal does not hap¬ pen, especially at low flow rates, undesirable error alarms will occur due to the different inertia and measurement inaccuracies of the measuring means. The rejection unit likewise makes up for the change of flow that occurs between the measuring means 12, 13 due to differences in temperature and/or pressure in the flow and return flow. Due to non-linearity in the measuring means 12, 13 there will at high flow velocities soon occur a dif¬ ference in the measuring results which is larger than the amount required in order to produce a signal to the motor of the motor valve 6 and actuate the alarm 16. In order to solve this problem the system is pro¬ vided with a variable cancellation device which, de- pending on the existing flow, accordingly will zero the measuring process. By means of these means and this method any leakage will be found immediately, and measures can be taken : to repair the leakages while these are minimized be¬ cause the supply of fresh water into the system is completely shut off. Moreover, measures can be taken to avoid for instance frost bursts and the like. Fig. 3 shows an example of a control unit in connec¬ tion with a single-pipe water system in a building. The system is connected to a main pipe 1 by means of a branch pipe 3. The branch pipe leads into the buil- ding 5, as indicated by the dotted line. Inside the building a motor valve 6 is inserted, who¬ se electric motor can shut off the water supply to the building. In series herewith a flow meter 8 is inserted which can be provided with an ordinary counter for the wa¬ ter supply to the building. This flow meter further¬ more transmits impulses in direct dependence on the water supply through the meter. The signal is sent to an electronic control unit 15 which will be explained below. The water pipe 10 of the building extends between the user outlets 17 in a generally known manner. Finally is shown an electronic unit 18, adjustable with respect to time and capacity, which can actuate the control unit 15 to any pre-determined water con¬ sumption and time interval. The control of the water flow in the system will now be described. Where the system is continuously controlled, the unit 18 is set at upper and/or lower limits as to when the water supply is to be stopped and shut off. Hereafter •the electronic control 15 will compare the signal from the flow meter 8 and, when the result is in ex¬ cess of the predetermined upper and lower limits, produce a signal to the motor valve 6 which will shut off the water supply to the system immediately. This exceeding of the limits will typically be caused by a burst in the pipe system, and further water damage will be prevented. If the water flow is below the limit, the water flow may either be increased by signalling to the motor valve 6 which will then open for further adding of water, and if this cannot be done, the water supply can be shut off and the installation disconnected, in order that this will not be further damaged due to a lack of water. Moreover, alarm may be given in a ge- nerally known manner. If the system is to be controlled primarily in terms of tightness, the unit 18 can be set to produce a signal to the control unit 15 within e.g. one hour in the middle of the night where usually no water is tapped. Any water consumption will therefore be cau¬ sed by a leakage which will cause the water supply to stop, because the flow is stopped from flowing through the motor valve 6. If there is a risk of unnecessarily shutting off the system, the unit 18 can for instance be set to repeat the control, e.g. within the following hour or during any other time interval. This will rule out any unin¬ tended disconnection of the system. By means of this system and this method a simple and reliable control of the water supply is achieved, whereby water damage and interruption of operations of water dependent installations can be avoided.

Claims: P A T E N T C L A I M S 1. Central heating system or a similar closed heating system with inlet and outlet for a heat carrying me- dium, c h a r a c t e r i z e d in that a volume flow meter (8, 9) with an electric output signal is inserted at the inflow and return flow of the medium, and a motor valve (6) for shutting off the flow (3) through the flow meter (8) and a non-return valve (7) for shutting off the return flow (4) after the return flow meter (9). 2. Method for controlling the tightness of the cen¬ tral heating system referred to in claim 1, c h a - r a c t e r i z e d in that the signal from the flow and return flow meter (8, 9), respectively, is compared in a control unit (15) which will produce a signal for actuating the motor valve (6), if a cer¬ tain value disparity is exceeded, for shutting off the flow (3) and perhaps will give signal to " an alarm (16). 3. Method for controlling the water flow in a water system for cold and hot water or in a similar single- p e system, in which liquid through pipes and under pressure is led to one or more user outlets, c h a r a c t e r i z e d in that the signal from the meter (8) in the control unit (15, 18) is compa¬ red with a pre-determined upper and/or lower water flow limit and when the flow is in excess of the up¬ per limit and/or below the lower limit, a signal is produced to actuate the motor valve (6) and perhaps an alarm. 4. Method according to claim 3, c h a r a c t e¬ r i z e d in that the comparison takes place within a pre-determined time interval.

Inventors: NIELSEN INGE, NIELSEN, INGE
Applicants: IK TRADING APS
Application year: 1987
Main classification: G01M3
IPC codes: F17D5, F24D10, G01M3