Replenishing and degassing device

Abstract

 The invention relates to a device for replenishing and degassing circulation water of a central heating system, which device can take a small form. The device comprises an expansion compartment and a replenishing compartment, a connecting line debouching into the bottom of the expansion compartment for connecting to the central heating system, a pressure-controlled expansion valve arranged between the connecting line and the expansion compartment and opening at a high pressure in the connecting line, and a pump actuable by a pressure-controlled switch at a low pressure in the connecting line, a level-controlled valve arranged between the expansion compartment and the replenishing compartment and opening at a low level in the expansion compartment, and a level-controlled replenishing valve opening at a low level in the replenishing compartment. The device is embodied as a self-supporting unit connectable by the connecting line to a central heating system.

Description

[0001] The invention relates to a device for replenishing and degassing the circulation water of a central heating system. Such a device is generally referred to as a server and is known from the international patent applications WO 95/20132 and WO 96/33372.

[0002] The known devices are bulky. The device according to the invention, referred to as microserver, can advantageously take a small form and is primarily intended for application as inexpensive mass-produced article in central heating systems for dwellings. The invention can however also be used for larger systems.

[0003] In addition, the microserver according to the invention is particularly intended for mounting instead of the traditional (hanging) expansion tank.

[0004] A suitable embodiment of the device according to the invention is characterized in claim 2. The expansion compartment is herein formed by the annular space round the cylindrical chamber.

[0005] An embodiment of the device according to the invention which is structurally simple and therefore favourable in terms of cost is obtained by applying the feature of claim 3.

[0006] A very suitable embodiment of the pressure-controlled switch is herein obtained with the embodiment characterized in claim 4. Owing to the pressure-dependent up and downward movement of the plunger the base plate is mounted such that the contacts thereof are closed when a pressure corresponding to a determined minimal operating pressure prevails in the central heating system.

[0007] A very advantageous further development is characterized in claim 5. In the case of a considerable water loss from the central heating system, for instance through leakage, a situation will arise with a low level in the replenishing compartment and simultaneously a low pressure in the central heating system. By applying the feature of claim 5 the pump will not be activated in this situation and the system will in principle switch off until the leakage is repaired and the system has been brought to pressure again.

[0008] Control of the replenishing valve is achieved in simple manner by applying the feature of claim 6. At a normal pressure level in the central heating system the replenishing valve will be activated in the desired manner to compensate water loss through for instance degassing of the c.h. water. However, when the pressure is too low as a consequence of leakage or the like, the replenishing valve will not be activated.

[0009] The invention will be further elucidated in the following description with reference to the annexed figures.

Figure 1

shows a partly broken away front view of a device according to the invention in a preferred embodiment;

figures 2-5

shows cross-sections corresponding with figure 3 of the device shown in figure 1 in four different operating positions;

figure 6

shows a side view of a float used in the device in three operating positions; and

figure 7

shows a schematic view of an alternative embodiment of a device according to the present invention.

[0010] In the manner of a usual expansion tank the microserver 1 is fixed with a connecting tube 6 to the expansion pipe of a c.h. system. A connection to the water supply system is made on replenishing valve 10. In addition, a connection to the sewer is possible by means of pipe 12.

[0011] Microserver 1 is divided into two compartments: an expansion tank 2 and a replenishing buffer 3 in an inner pipe 4.

[0012] The pressure in expansion tank 2 can vary from an underpressure to practically atmospheric. The pressure in replenishing buffer 3 is always atmospheric due to a direct connection with the outside air.

[0013] Via connection 6 on the expansion pipe to the c.h. system the central heating water under pressure is guided to a distribution dish 5 in the bottom of tank 1. Distribution dish 5 connects the c.h. system to main control valve 7. From the connection onto the c.h. system to the underside of the plunger of the main control valve the pressure is substantially the same as the pressure in the c.h. system.

[0014] At high pressure in the c.h. system the main control valve 7 regulates the feed of water out of the c.h. system to expansion tank 2, whereby the pressure in the c.h. system is reduced. In addition, the main control valve transfers a low pressure in the c.h. system to a mercury switch 26, whereafter a pump 28 is switched on to increase the pressure in the c.h. system. The pressure in the c.h. system can be adjusted to any desired value, depending of course on the embodiment of the microserver in terms of pump capacity and main control valve.

[0015] By adjusting the tensioner (screw with lock) the pressure can be increased (screwing in) or decreased (unscrewing). A tensioning bracket 15 is rotated upward or downward with the tensioner whereby the upper cover 16 on the valve housing is then moved in the same direction. The spring tension on the plunger in main control valve 7 is hereby increased or decreased.

[0016] The different positions of the plunger are transferred via a connecting rod 17 to a base plate 24 on which are mounted two mercury switches 25, 26. When the pressure has reached the lowest level, the plunger will pull base plate 24 so far downward via connecting rod 17 that mercury switch 26 associated with pump 28 makes contact as shown in figure 3. Pump 28 then draws water out of expansion tank 2 via suction line 27 and pumps this water to the c.h. system via pressure line 29 which is connected to connecting tube 6. The pressure in the c.h. system is increased, whereby the plunger in main control valve 7 is moved upward from the lowest position. Eventually the base plate 24 with mercury switches 25, 26 is hereby tilted into the neutral position of fig. 2 and pump 28 is switched off. At a higher pressure the base plate is held in a neutral position. Connecting rod 17 can move with limited freedom in a slot in base plate 24.

[0017] In the lowest position the plunger in the main control valve seals fully against a seat 20. This ensures a lowest pressure in the c.h. system. When the plunger is raised it seals practically completely with a piston/cylinder fitting in cover 16, so that the c.h. system and replenishing buffer 3 cannot come into communication with each other.

[0018] Some leakage is permitted, particularly to allow gases to escape from the c.h. system. Gas will pass more easily along the seal in cover 16, but for water the seal is good.

[0019] Because the valve is controlled directly by water from the c.h. system, wherein the plunger is opened further and eventually completely as the pressure increases, as shown in figure 2, safety in respect of overpressure in the c.h. system is ensured. A separate safety valve is therefore unnecessary. It will be evident that when main control valve 7 is opened, wherein the plunger moves upward, the pressure in the c.h. system becomes lower as a result of water being taken from the c.h. system into the expansion tank until a new balance has been found at the set pressure.

[0020] There is the further option of draining excessive quantities of water from expansion tank 2 via overpressure valve 9 and subsequently via replenishing buffer 3 and sewer connection 12.

[0021] When the liquid level in the expansion tank falls to below a minimum level, inlet valve 22 is opened by float 23 as shown in figure 4. If there is too great an underpressure in expansion space 2, a small opening is first created by displacing a small pin valve 33 in inlet valve 22 whereby the underpressure is eliminated. The float will then certainly be able to open inlet valve 22.

[0022] Figure 6 shows an embodiment variant of the inlet valve or replenishing valve 22. Figure 6A shows the closed situation and figure 6B the situation wherein float 23 has descended just so far that pin valve 33 leaves clear the opening in inlet valve plate 22. The pressure difference over inlet valve plate 22 becomes small due to this opening, so that float can press the whole valve plate further open into the situation shown in figure 6C. Float 23 is embodied in this embodiment as a vessel in which water remains, thereby increasing the downward force of the float for pressing open the valve.

[0023] After opening of inlet valve 22 water flows out of replenishing buffer 3 into expansion tank 2. The water level in replenishing buffer 3 will hereby be reduced. A float 21 descends together with the liquid level in replenishing buffer 3. Under the influence of the spring tension of spring-controlled limiter 19 the connecting rod 18 is co-displaced downward as shown in figure 4. Base plate 24 is carried along with this movement and tilts mercury switch 25 for replenishing valve 10, whereby replenishing valve 10 is switched on. Switch-off of replenishing valve 10 takes place in reverse sequence.

[0024] The moment at which the replenishing valve is switched on depends on the angle of inclination of mercury switch 25 mounted on base plate 24. The water level in the replenishing valve will be reduced the moment the pump is activated. A low pressure in the c.h. system is after all the reason to pump water out of the expansion tank to the c.h. system. The position of the plunger in main control valve 7 is herein low and mercury switch 26 is closed.

[0025] The different angles of inclination or angular positions of mercury switches 25 and 26 on base plate 24 are chosen such that a correct pressure is first obtained in the c.h. system. Mercury switch 26 remains closed until the plunger in main control valve 7 has reached a suitable higher position, which is the case when the pressure in the c.h. system is equal to the set value. Base plate 24 will now take up a neutral position on the side of rod 18. The now altered angle of inclination causes pump 28 to switch off and replenishing valve 10 to open. On base plate 24 the mercury switch 25 for the replenishing valve is now closed and mercury switch 26 for the pump is open.

[0026] It is however possible for the water level in the expansion tank to be at the minimum level while the c.h. system is fully operational. This may occur due to initial water leakages in a c.h. system, this being dealt with at length in the above mentioned patent applications. Work may also have been carried out on a c.h. system wherein water has been lost. The water cools after the c.h. system has been switched off. The microserver must now compensate the reduction in the volume of water in the c.h. system, while a minimal amount of water is present. If the c.h. system is sufficiently sealed, sufficient filling water will always be available in the microserver to compensate volume reduction during cooling of water in this c.h. system.

[0027] The microserver must be able in a critical situation to maintain the pressure in the c.h. system with at least the quantity of water equal to the volume between the minimum and basic level of the expansion tank increased by the quantity of water present in the replenishing buffer. If this minimal supply of this collective volume of water present in the microserver virtually equals the maximum quantity of expansion water of the c.h. system (volume difference of water at highest operating temperature and lowest temperature at switch-off), the microserver can permanently ensure a correct operating pressure in the c.h. system.

[0028] When it is found that this minimum quantity of water is inadequate to realize a proper operating pressure in the c.h. system, this indicates an unacceptable water loss in the c.h. system through leakage. In this extreme situation the microserver remains "inoperative" until the problems of the c.h. system have been resolved. The c.h. system will first have to be brought to sufficient pressure before the replenishing valve can be opened. Base plate 24 with mercury switches 25 and 26 is then pulled downward on both sides, replenishing and pump side, whereby both mercury switches remain switched to open. This is shown in figure 5.

[0029] Another safety device is formed by vacuum valve 8 and pressure valve 9. Vacuum valve 8 ensures a lower limit of the underpressure in the expansion tank, for instance an underpressure of a maximum of 0.5 bar below atmospheric or 0.5 bar absolute. Too great an underpressure can among other things endanger proper operation of pump 28. There will never be too great an underpressure due to the air buffer in the top of the expansion tank. As the case may arise, the water level in the expansion tank may have been too high, whereby an excessive underpressure is created during pumping out. Air can then be admitted with vacuum valve 8. Conversely, a situation may occur wherein the supply of water from the central heating system is too great. Pressure valve 9 then prevents a pressure occurring in the expansion tank which is higher than about atmospheric pressure. In such disastrous situations pressure valve 9 could open at a pressure of for instance 0.1 bar above atmospheric to drain the excess water.

[0030] As safeguard against the danger of contamination of the drinking water the microserver has two atmospheric interrupters. Firstly, there is a safe height difference between sewer connection 12 and the opening of outlet pipe 11. In addition, the top part of the horizontal part of the sewer connection is partially removed (13). Finally, it is possible in the design to make an opening in the wall in inner pipe 4 between outlet pipe 11 and the connection to sewer 12, whereby a further atmospheric interrupter is obtained. The dimensioning of diameters, distances and openings must be in accordance with local water safety regulations.

[0031] Figure 7 shows a schematic view of an alternative embodiment of a device according to the present invention. Corresponding components are designated with the same reference numerals as in figure 1.

[0032] Main control valve 7 is under the control of a membrane and, in contrast to the embodiment of figure 1, is arranged at the top of device 36. At high pressure the membrane is pushed aside and water can flow through tube 6 out of the c.h. system into expansion tank 2.

[0033] When the pressure in the c.h. system falls again, switch 37 in main control valve 7 is energized, whereby pump 28 is set into operation to pump water out of expansion tank 2 back into the c.h. system via suction line 27.

[0034] Underpressure prevails in tank 2. As described in the foregoing with reference to figure 1, gas is hereby extracted from the water. This gas can escape via discharge 38 which debouches outside expansion tank 2 and replenishing buffer 3. Discharge 38 is per se closed by a valve 39 which is loaded with a spring and which is pressed open under the influence of the escaping gas. Float 40 in discharge 38 serves to ensure that no water can escape through discharge 38, for instance if the water level in expansion tank 2 is higher than this float and/or when main control valve 7 is opened to admit water from the c.h. system into expansion tank 2 through connecting tube 6.

[0035] In this embodiment a minimum fixed air volume remains present to preclude an excessive underpressure at a low level in expansion tank 2. When there is a maximum level in expansion tank 2, the spring-loaded valve 42 will open when the (over)pressure becomes too great, whereby the excess expansion water can be drained to the sewer via replenishing buffer 3 and outlet 12.

[0036] Arranged in replenishing tank 3 is a float 35 with which the water level in the replenishing tank is controlled in a similar manner as in the embodiment of figure 1, although via a central control 41 comparable to base plate 24 with mercury switches 25 and 26 of figure 1. In response to a signal from float 35 the control 41 opens replenishing valve 10 so as to increase the liquid level in replenishing buffer 3 via pipe 11. Too high a level in replenishing buffer 3 can also be prevented here using the outlet 12 to the sewer.

[0037] Arranged at the bottom of expansion tank 2 under replenishing buffer 3 is another float 23 which is connected for mechanical tilting to an opening at the bottom of replenishing buffer 3 in order to operate a valve 42 which is held closed under spring force. At a low water level in expansion tank 2 float 23 descends and valve 42 is pressed away so that water can flow out of replenishing buffer 3 into the expansion tank. When float 23 has once again risen so far that valve 42 is closed, float 35 once again comes into operation to increase the level in replenishing buffer 3 in co-action with control 41 and replenishing valve 10. This preferably takes place only when the c.h. system has been brought to pressure, since the actual deficiency of water in expansion tank 2 is only then apparent. A float 34 is further arranged which generates a signal as an indication that such a low level has been reached in expansion tank 2 that it is no longer possible to build up pressure in the c.h. system because too little water is present in the expansion tank for this purpose. This may arise for instance when a pipe fracture has occurred. In such a situation the control 41 is programmed to keep pump 28 inoperative and replenishing valve 10 is not opened.

[0038] Expansion valve 7 comprises a membrane 43 which in figure 7 lies parallel to the connecting conduit 6 and the whole membrane 43 is located outside this conduit. Membrane 43 can thus take a large form. A large surface area of membrane 43 enhances conversion of the pressure prevailing in the c.h. system into a movement of the plunger with stop connected to the membrane by arm 45. Membrane 43 is also under the influence of spring 44 which controls the pressure characteristics of membrane 43.

[0039] Arranged on membrane 43 is an arm 45 with a stop which, in the position of membrane 43 tending to the left in figure 7, closes a passage in connecting conduit 6. That is, when the pressure prevailing in the c.h. system is insufficiently high to cause membrane 43 in figure 7 to deflect to the right, the stop on arm 45 will close the passage in connecting conduit 6. In this way water from the c.h. system will then only reach expansion tank 2 when the pressure in the c.h. system is sufficiently high therefor.

[0040] In the intermediate positions between closing and opening there can then be a controlled leakage loss, whereby a dynamic process of degassing results, also when there is no immediate necessity for pressure correction of the heating installation. Due to the leakage loss the pump 28 will come into operation at any moment to compensate the pressure fall caused by this controlled leakage loss. In the case of a malfunction wherein the pump does not function, the stop closes the heating installation completely, whereby a minimal pressure is always maintained (and the heating installation cannot empty via device 36).

[0041] In the above described first preferred embodiment use is made for the electrical circuits of mercury switches wherein a mercury globule in a closed glass housing moves reciprocally due to tilting and alternately mutually connects or disconnects two contact pins. Any switch with the same properties can of course be used. A hysteresis in the circuits can be easily created by choosing mutually differing angles of inclination for the switches. The base plate is preferably suspended in a neutral position with an elastic or flexible connection. In the second embodiment use is made of a so-called reed contact which can be switched on by the approach of a magnet connected to arm 45 and membrane 43.

[0042] As addition or alternative it is quite possible per se to position the replenishing compartment other than centrally (as in the embodiments of the figures) relative to the expansion compartment, for instance laterally. The choice of the form of the two compartments can also be other than stated above. In addition, the diverse functions can also be realized in a manner other than purely mechanically, for instance with electrical pressure sensors and electrical or electromagnetic control of the diverse valves etc. in a therefore much more active manner.

Claims

1. Device for replenishing and degassing circulation water of a central heating system, comprising an expansion compartment (2) and a replenishing compartment (3), a connecting line (6) debouching in the expansion compartment (2) for connecting to the central heating system; a pressure-controlled expansion valve (7) arranged between the connecting line (6) and the expansion compartment and opening at a high pressure in the connecting line (6), and a pump (28) actuable at a low pressure in the connecting line (6); a level and pressure-controlled valve (42; 22, 23) arranged between the expansion compartment (2) and the replenishing compartment (3) and opening at a low level in the expansion compartment (2); and a level-controlled replenishing valve (10, 25) opening at a low level in the replenishing compartment (3), wherein the device is embodied as a self-supporting unit (1, 36) connectable by the connecting line (6) to a central heating system.

2. Device as claimed in claim 1, wherein the expansion compartment (2) is formed in a substantially cylindrical vessel and the replenishing compartment (3) is formed in a substantially cylindrical chamber (4) accommodated in this vessel.

3. Device as claimed in claim 1 or 2, wherein the expansion valve (7) comprises a plunger displaceable counter to spring pressure and the pressure-controlled switch (26) is activated when the plunger is displaced through a predetermined distance.

4. Device as claimed in claim 3, wherein the plunger is disposed for vertical movement and is connected eccentrically (17) to a base plate (24) which is pivotable on a horizontal axis and bears an inclination-sensitive switch, such as a mercury switch (26), which forms the pressure-controlled switch activating the pump (28).

5. Device as claimed in claim 4, wherein a float (21) arranged in the replenishing compartment (3) is likewise connected eccentrically (18) to the base plate (24) such that in the case of a low level in the replenishing compartment (3) it urges the base plate (24) into a pivoted position opposite to the pivoted position associated with a low pressure in the connecting line (6).

6. Device as claimed in claim 5, wherein the base plate (24) bears a second inclination-sensitive switch, such as a mercury switch (25), with which the replenishing valve (10) can be activated.

7. Device as claimed in claim 1 or 2, wherein the expansion valve (7) comprises a membrane (43) which is suitable, in accordance with pressure prevailing in the c.h. system, to selectively open and close the connection between the c.h. system and the expansion compartment.

8. Device as claimed in claim 7, wherein the pressure resistance of the membrane (43) is determined by a spring (44).

9. Device as claimed in claim 7 or 8, wherein the membrane (43) is connected to an arm (45) which extends toward a passage in the connecting line (6) and on which is arranged a stop closing the passage in a position of the membrane (43) corresponding with low pressure in the c.h. system.

Drawing