GB2284467A - Venting and expansion system for a central heating installation - Google Patents

Abstract

A venting and expansion system for a central heating installation having a hot water tank (20), an indirect heating coil (9) fed by a boiler (not shown) and a level controlled water storage tank (23) feeding the system. The system uses two chambers (1) and (2) connecting the top of tank (20) and the coil (9) with an expansion pipe (25) leading to tank (23). The chamber (1) has internal tubes (7) and (8) which allows the coil (9) to initially fill through pipe (21) from the tank (20) through chamber (2). Through hot water expansion and expelled air chamber (1) becomes an air-lock (see Figure 9) and chamber (2) maintains the head in coil (9). <IMAGE>

Description

TITLE Venting System for the Control and Expansion of Primary Water in a Central Heating Installation This invention relates to a venting system for the control and expansion of primary water in a central heating installation and a central heating installation containing the venting system.

At present there are on the market expansion vessels that are used to take-up the expansion of water when heated. The use of these create a sealed system and have to be sized in accordance with the volume of the water within the system, and also the pressure to which this is subjected.

This method has many disadvantages as the system may fail due to loss of pressure when the system is vented to remove air trapped in the radiators. Also there is the danger that the diaphragm of the expansion vessel may become work or age hardened, causing cracking and leaking.

The balancing of the system requires skilled technicians to install and maintain and is quite expensive.

There is also the use of feed and expansion tanks; these are separate tanks from those used to store the domestic water within a house. These feed and expansion tanks must be situated at a higher level than the highest point on the central heating system and require separate cold feed pipes to maintain the water levels within the tank. They must also be fitted with overflow warning pipes, vent pipes from the heating system and feed pipes to the heating system. These tanks must be protected from frost, and must also be situated where it is possible to gain access for maintenance to the ball valves.

The venting system of this invention largely avoids or mitigates the aforementioned problems as it is not a sealed system and does not require a separate feed and expansion tank. The system of this invention is based on a venturi method of feeding water into a heating installation and at the same time creates an expansion chamber that is constantly recharged by the natural discharge of air from water when heated.

According to one aspect of the invention there is provided a venting system for the control and expansion of water in a central heating installation, the venting system comprising a first expansion chamber adapted to be connected by a connecting pipe to a second expansion chamber of the same volume as that of the first expansion chamber and so that the first expansion chamber is disposed above the second expansion chamber; the first expansion chamber adapted to be mounted so that a first opening which is a vent opening is disposed at the top of the first expansion chamber, the first opening being provided with connecting means enabling it to be connected to an expansion pipe forming part of a central heating installation, the first opening forming the end of a first vent tube passing down into the first expansion chamber and terminating in an open end short of the bottom of the first expansion chamber, and that a second opening which is a vent opening is disposed at the bottom of the first expansion chamber, the second opening which is a primary feed and vent opening being provided with connecting means enabling it to be connected to one end of the said connecting pipe, the second opening forming the end of a second vent tube passing up into the first expansion chamber and terminating in an open end short of the top of the first expansion chamber, and that a third opening which is a vent opening is disposed at the bottom of the first expansion chamber, the third opening being spaced from the second opening and from the first vent tube, the third opening being provided with connection means enabling it to be connected to a vent pipe leading from a hot water tank or cylinder forming part of a central heating installation; the second expansion chamber adapted to be mounted below the first expansion chamber and so that a fourth opening which is a primary feed and vent opening is disposed at the top of the second expansion chamber, the fourth opening being provided with connecting means enabling it to be connected to the other end of the said connection pipe, and that a fifth opening which is a feed and expansion opening is disposed at the bottom of the second expansion chamber, the fifth opening being provided with connecting means enabling it to be connected to a pipe leading to a primary system forming part of a central heating installation.

According to another aspect of the invention there is provided a central heating installation containing the venting system of the invention.

The second expansion chamber may be one that has been formed by welding or brazing two half chambers together, one half chamber containing the said fourth opening and the other half chamber containing the said fifth opening.

By way of example preferred forms of the invention will now be described with reference to the accompanying diagrammatic drawings, wherein: Figure 1 is a sectional elevation of a first expansion chamber, Figure 2 is a top view of the expansion chamber of Figure 1, Figure 3 is a bottom view of the expansion chamber of Figure 1, Figure 4 is a sectional elevation of a second expansion chamber, Figure 5 is a top view of the expansion chamber of Figure 4, Figure 6 is a bottom view of the expansion chamber of Figure 4, Figure 7 is an exploded view of the expansion chamber of Figure 4, Figures 8 and 9 illustrate parts of central heating installations employing heat expansion chambers as illustrated by Figures 1 to 7, Figure 10 shows a central heating installation employing heat expansion chambers as illustrated by Figures 1 to 7 (the dotted lines indicating an alternative disposition of the two heat expansion chambers), and Figures 11 and 12 show in section to a larger scale the respective heat expansion chambers appearing in Figure 8.

The illustrated venting system for the control and expansion of primary water in a central heating installation includes two independent copper, steel or plastic heat expansion chambers 1 (Figure 1) and 2 (Figure 2) which may be circular, square or rectangular in shape.

Each chamber 1, 2 is of the same volume as the other to ensure that as air or water is introduced into or discharged from either chamber 1,2 then air or water from the other chamber 1,2, will replace the same volume.

The expansion chambers 1,2 may be in various sizes as required for larger or smaller heating installations. To reduce manufacturing costs and to standardise, the expansion chambers may be made in five basic sizes although special sizes can be made to order.

The first expansion chamber 1 is provided with a vent boss 3 surrounded by a top plate 4 at the top of the chamber 1 and also with a primary feed and vent boss 5 and a secondary vent boss 6 surrounded by a bottom plate 10.

Vent tubes 7 and 8 are housed by the chamber 1.

The second expansion chamber 2 is provided with a primary feed and vent boss 11 surrounded by a top plate 12 and a feed and expansion boss 13 to a primary system surrounded by a bottom plate 15. Figure 7 shows separate top spun section 16 and a bottom spun section 17 which are then brazed or welded together to form the chamber 2 of Figure 4, the welded or brazed joint being indicated at 14.

It has to be remembered that the water contained in a central heating installation expands by approximately 4% of its volume when heated by 45 degrees Fahrenheit (270 Celsius). It is this expansion that must be catered for by any expansion vessel or tank. To achieve this, the expansion chamber 2 is fitted into a primary circuit as shown in Figures 8 to 12. The expansion chamber 2 may be fitted in the circuit at any suitable position as shown in Figures 8 to 10. The method of fitting in the expansion chamber is by the two connections 11 and 13. The top connection 11 is connected by a connecting pipe 18 to the first expansion chamber 1. Chamber 1 has the three connections 3, 5 and 6. The top connection 3 continues down into the chamber 1 to within 10 mm from the bottom of the chamber 1 and terminates in an open end 19 of tube 8.

This connection 3, 8, 19 forms part of the vent and expansion pipe 21 from the secondary stored water in hot water cylinder 20 (provided with heating coil 9) and combines to make a dual vent and expansion for both the secondary and primary systems.

In the bottom surface of the expansion chamber 1 there are two connections 5 and 6. Connection 6 allows air from the secondary stored water in the hot water cylinder 20 to vent upwards and out through the vent pipe 21. The second connection 5 continues upwards as vent tube 7 into the chamber 1 and terminates 10 mm from the top of the chamber 1 at open end 22. The vent tube 7 allows water to feed into the primary system and also allows the water to expand into the chamber as it is heated. The continuous expansion and contraction of the heated water is catered for in this chamber 1. This follows because as the water from the cylinder 20 is pressurised from cold water tank 23 (24' denoting the level of water in the tank) above, the water in the cylinder 20 will continue to rise up and into the vent pipe 21 and also into the expansion chamber 1.

During the initial filling of the primary system a vent is opened to allow air to escape and fill the primary system. This is achieved by the following method.

Water will continue to rise within the expansion chamber 1 and will flood over the tube 7 leading to the lower expansion chamber 2. Water will continue to feed into the lower chamber 2 all the time that a vent in the installation is opened and whilst there is a negative pressure within the primary system. Once the vent is closed or when the system is filled, a back pressure will develop equal to the head of water supplying the secondary water in the cylinder 20. The air that is trapped in the chamber 2 cannot escape because there is a water trap in the upper chamber I which prevents this.

As the primary water expands during heating the water will enter the expansion chamber 2 and force the air trapped in the chamber 2 upwards into the expansion chamber 1, this will in turn push the air contained in the chamber 1 up and out through expansion pipe 25 to outside atmosphere.

As the water cools this will contract causing a negative pressure in the chamber 2. Water will then again flow over the tube 7 in the upper chamber 1 until pressure has been restored.

At any time when either a radiator (not shown) has been removed and replaced or when a heating system has been vented of air in the radiator's water, water will automatically flow to refill the system.

The system is virtually trouble-free as it has no moving parts or diaphragms and will not require servicing once it has been installed.

Filling of the venting system is described below with particular reference to Figures 8 and 9. As water from the cold storage tank 23 above fills the hot water cylinder 20 the water will automatically rise through the chamber 1 and into the vent pipe 25 leading to the storage tank 23. As it does so the water will pass through vent pipe 21 and flood over the vent tube 7 of chamber 1 and flow down into the lower chamber 2 located above the heating coil 9. This will continue to fill the primary system until the pressure or water level is equal to that of the water in the cold water storage tank 23 fitted at high level. The primary system will automatically refill every time the primary system is vented or when a radiator (not shown) has been removed and replaced.

Operation of the venting system will be described with reference to Figure 10. Once the primary system has completed filling then an air lock will form in the chamber 2. This will form an effective expansion barrier when the primary system has been heated. As the water in the cylinder 20 is constantly replaced and reheated this will produce a constant stream of bubbles that will pass through the chamber 2. The bubbles of air will be trapped in the chamber 1 until this is also filled with air as shown in Figure 9. This will then form a double air lock to the primary circuit. Surplus air will then escape through the vent pipe 25. 26 denotes a boiler of circulator in the circuit.

Claims (5)

1. A venting system for the control and expansion of water in a central heating installation, the venting system comprising a first expansion chamber adapted to be connected by a connecting pipe to a second expansion chamber of the same volume as that of the first expansion chamber and so that the first expansion chamber is disposed above the second expansion chamber; the first expansion chamber adapted to be mounted so that a first opening which is a vent opening is disposed at the top of the first expansion chamber, the first opening being provided with connecting means enabling it to be connected to an expansion pipe forming part of a central heating installation, the first opening forming the end of a first vent tube passing down into the first expansion chamber and terminating in an open end short of the bottom of the first expansion chamber, and that a second opening which is a vent opening is disposed at the bottom of the first expansion chamber, the second opening which is a primary feed and vent opening being provided with connecting means enabling it to be connected to one end of the said connecting pipe, the second opening forming the end of a second vent tube passing up into the first expansion chamber and terminating in an open end short of the top of the first expansion chamber, and that a third opening which is a vent opening is disposed at the bottom of the first expansion chamber, the third opening being spaced from the second opening and from the first vent tube, the third opening being provided with connection means enabling it to be connected to a vent pipe leading from a hot water tank or cylinder forming part of a central heating installation; the second expansion chamber adapted to be mounted below the first expansion chamber and so that a fourth opening which is a primary feed and vent opening is disposed at the top of the second expansion chamber, the fourth opening being provided with connecting means enabling it to be connected to the other end of the said connection pipe, and that a fifth opening which is a feed and expansion opening is disposed at the bottom of the second expansion chamber, the fifth opening being provided with connecting means enabling it to be connected to a pipe leading to a primary system forming part of a central heating installation.

2. A venting system according to Claim 1, wherein the second expansion chamber has been formed by welding or brazing two half chambers together, one half chamber containing the said fourth opening and the other half chamber containing the said fifth opening.

3. A central heating installation incorporating the venting system according to Claim 1 or 2.

4. A venting system for use in a central heating installation constructed and arranged to function as described herein and exemplified with reference to the drawings.

5. A central heating system constructed and arranged to function as described herein and exemplified with reference to the drawings.