The present invention relates to blow-off vents for heating systems and other similar systems. It has application in domestic central heating systems as well as heating systems for industrial applications, but could equally be used in any system which includes a blow-off vent for venting fluid, either gas or liquid, under pressure.

It is standard practice to provide a blow-off vent for central heating systems to allow hot air and steam to escape through an external wall of a house or building. Typically the vent is in the form of a simple pipe with two 90° bends at the end so that the open end of the pipe is directed back towards the wall. This is to prevent hot air and steam from being ejected outwards away from the wall which might otherwise create a hazard, for example to people walking past.

It can be a problem with such known vents that, because they are made from two right angle bends as well as the main pipe, the time taken, and hence the cost, to install them can be significant. Also, they tend to direct all of the hot air and steam onto a very small area of the house wall, which can mark it. They also are not particularly attractive.

The present invention therefore provides a vent system for a heating or similar system comprising a vent pipe extending substantially horizontally through an external wall of a building and terminating at an end, and having at least one aperture therein, which may be at or towards the end, and a cowl extending around the end of the pipe, and optionally at least partly around the at least one aperture, and being open towards the wall so that fluid escaping along the pipe and through the at least one aperture will impinge upon the cowl and thereby be deflected at least partially back towards the wall.

The at least one aperture may be at or towards the end of the pipe section.

Preferably the cowl is dished and has an outer edge which extends around the pipe and is spaced therefrom. Preferably said outer edge is further from the end of the pipe, in the axial direction of the pipe, than any part of the at least one aperture. Preferably the at least one aperture is defined in the side of the pipe. In this case the cowl preferably seals the end of the pipe so that the fluid can only escape through the at least one aperture.

Preferably the at least one aperture is spaced from the end of the pipe so that the end of the pipe is in contact with the cowl over substantially the whole of its circumference. This helps to form a strong assembly. Alternatively the cowl may be supported away from the end of the pipe so that fluid can escape from the pipe through said end.

The cowl may be supported on at least one support portion of the pipe. The support portion may have been deformed outwards to leave the at least one aperture in the pipe.

The present invention further provides a pipe cowl fitting comprising a pipe section terminating at an end, and having at least one aperture at or towards the end, and a cowl extending around the end of the pipe section and the at least one aperture and being open in a direction away from said end so that, in use, fluid escaping along the pipe section and through the at least one aperture will impinge upon the cowl and thereby be deflected at least partially in a direction back along the pipe section away from said end.

The present invention still further provides a method of fitting a cowl to a vent pipe for a central heating system the method comprising providing a cowl fitting according to the invention and connecting the fitting to the end of a vent pipe for the central heating system.

Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which:

• Figure 1 is a perspective view of a pipe cowl fitting according to a first embodiment of the invention;
• Figure 2 is a side view of the fitting of Figure 1;
• Figure 3 is a section through a pipe cowl fitting according to a second embodiment of the invention;
• Figure 4 is a section through a pipe cowl fitting according to a third embodiment of the invention;
• Figure 5 is a section through a pipe cowl fitting according to a fourth embodiment of the invention;
• Figure 6 is a section through a pipe cowl fitting according to a fifth embodiment of the invention; and
• Figure 7 is a section through a pipe cowl fitting according to a sixth embodiment of the invention.

Referring to Figures 1 and 2, a pipe cowl fitting 10 comprises a pipe section 12 and a cowl 14. The pipe section is straight and of circular cross section being open at one end 16 and closed off at the other end 18 by the cowl 14. A ridge 19 extends around the pipe section 12 close to the open end 16. The ridge 19 is formed by deforming the pipe section 12 outwards to form a channel on the inside of the pipe section, and the channel has solder 21 in it for attaching the fitting 10 to a pipe. The cowl 14 is dished or domed being approximately parabolic in cross section had having a circular edge 20. The closed end 18 of the pipe section 12 extends into the cowl 14 and is joined directly to the center of its inside surface 22 by brazing, such that the cowl 14 is supported on the closed end 18 of the pipe section 12. The pipe section 12 has a pair of apertures 24 in its side near to the closed end 18. These are in the form of slots extending longitudinally along the pipe section 12. The cowl 14 extends from the closed end of the pipe section 12 outwards and back along the pipe section 12 away from the closed end 18 slightly further than the apertures 24. Its edge 20 therefore extends around the pipe section 12 at a point further from the end 18 of the pipe section than any part of the apertures 24.

Referring to Figure 3, in use a boiler 30 of a central heating system has a vent pipe 32 which extends through an exterior wall 34 and has its end 36 projecting horizontally from the wall 34. The fitting 10 is fitted to the end 36 of the vent pipe 32, and is heated to melt the solder 21 inside the ridge 19 thereby to attach the fitting 10 to the vent pipe 32. Hot air and steam passing through the vent pipe 32 therefore escape through the apertures 24 and impinge on the cowl 14 which acts as a baffle and dissipates energy including heat from the gas and steam, which is re-directed at least partly back along the pipe section 12 towards the wall 34. This prevents it from being ejected outwards from the wall and thereby provides protection, for example for people standing by the wall.

It will be appreciated that, instead of a solder joint, the fitting could to connected to the vent pipe by other methods, for example using a simple sealing O-ring inside the ridge 19.

Referring to Figure 4 in a second embodiment of the invention the cowl 40 is part conical rather than domed, with a circular flat portion 43 in its center which fits over the closed end 44 of the pipe section 46. There are four apertures 42 towards the closed end 44 of the pipe section 46. Apart from this the second embodiment is the same as the first.

Referring to Figure 5, in third embodiment the fitting is similar to that in the second embodiment, but the apertures 50 in the pipe section 52 are formed as semi-circular cut-outs 53 at the closed end 54 of the pipe section 52. The cowl 56 is therefore connected to the pipe section 52 only on support portions 58 formed between the cut outs 53, rather than around its whole circumference.

Referring to Figure 6, in a fourth embodiment the apertures 60 in the pipe section 62 are each formed by cutting around three sides of a portion of the pipe section 62 so as to form a tab 64 in the side of the pipe section 62. The tab 64 is joined to the rest of the pipe section 62 only at one end 66 closest to the closed end 68 of the pipe section 62, and is bent outwards to form a supporting limb. The cowl 70 is connected to the pipe section by joining the inside surface 72 of the cowl 70 to the outer ends 74 of the tabs 64. The cowl 70 is supported so that it is clear of the end of the pipe section 62. Therefore steam and hot air can escape from the pipe section 62 both through the end 68 of the pipe, and through the apertures 60 in the side of the pipe. Since the cowl extends over all of the apertures including the end of the pipe, it will deflect air and steam passing through all of those apertures back towards the wall.

Referring to Figure 7, a fifth embodiment is the same as the fourth except that the tabs 80 in the pipe section 82 are each formed by making two parallel longitudinal cuts in from the end 84 of the pipe section 82.

Referring to Figure 8, in a sixth embodiment the end 90 of the pipe section 92 has small portions bent over to form barbs 94. The cowl 95 has holes 96 through it, and the barbs 94 are pushed through the holes 96 and snap outwards to fit the cowl to the pipe section 92. A further ridge 98 on the pipe section 92 prevents the cowl 95 from sliding along the pipe section 92. This embodiment therefore provides a simple snap-fit connection between the cowl 95 and the pipe section 92.