GB2536282A

GB2536282A - Self-closing air brick

Info

Publication number: GB2536282A
Application number: GB1504255.9A
Authority: GB
Inventors: Mallett Timothy
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-03-13
Filing date: 2015-03-13
Publication date: 2016-09-14
Also published as: GB201504255D0

Abstract

A hollow air brick 2 comprising a front face with airflow openings; a vane (30, Fig. 4) pivotally mounted behind the front face that rotates between a first open position permitting ventilation and a second closed position inhibiting ventilation; and a temperature sensitive mechanism (20, Fig. 3) adapted to rotate the vane to its second position when the temperature is below a threshold value. The temperature sensitive mechanism may be a bimetallic coil having one end fixed inside the air brick and the other end connected to a projection at one end of the vanes pivoting axis. Alternatively the temperature sensitive mechanism may either be a snap acting bimetallic disc that triggers the rotation of the vane or a switch. The threshold temperature may be the freezing point of water.

Description

SELF-CLOSING AIR BRICK

Technical Field

[0001] The present invention relates to air bricks or ventilation bricks of the type used to facilitate ventilation of underfloor spaces, particularly under suspended timber floors. If such spaces are not ventilated, condensation can build up and lead to rotting of the timbers. Similarly, cavity walls require ventilation. Air bricks are installed to satisfy the ventilation requirements of building regulations.

[0002] It is normal practice to provide air bricks which have a grille of through holes. Historically, cast iron or clay air bricks have been provided, but modern air bricks are typically made from moulded plastics material. There is a British Standard BS 493:1995 Al which covers louvre design air bricks and they are widely available.

[0003] While it is necessary to maintain air circulation in the ventilated space, there may be conditions when it is desirable to temporarily close the opening.

Background Art

[0004] Air brick protectors for use during flood alerts have been provided. These typically require manual fixing. Examples are described in GB2472146A (Clarke) and GB1124752 (Close).

[0005] When temperatures are very low, it is desirable to limit the amount of ventilation temporarily in order to reduce heating costs. However, to block ventilation altogether is undesirable and will defeat the object of having air bricks in place.

[0006] It is also undesirable to have to go outside in extreme conditions to fit prior art air brick protectors.

Disclosure of Invention

[0007] The present invention seeks to solve the technical problem of temporarily restricting ventilation in extreme temperature conditions by providing a modified hollow air brick having a temperature sensitive self-closing device as described in the accompanying claims.

[0008] Since the self-closing device responds to temperature, the ventilation can be restored when the temperature rises again in order to eliminate the risk that the householder may forget to unblock the air brick.

Brief Description of Drawings

[0009] In order that the invention can be well understood an embodiment thereof will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which: [0010] Figure 1 shows a front view of a standard louvre fronted air brick which has been modified with the self-closing device of the present invention; [0011] Figure 2 shows a side view of the air brick of Figure 1; [0012] Figure 3 shows an exploded view of a temperature sensitive device in the form of a bimetallic coil and cover; [0013] Figure 4 shows a perspective view of a vane; and [0014] Figure 5 shows a perspective view of the modified air brick viewed from the rear showing the vane moving toward its closed second position. Mode(s) for Carrying Out the Invention [0015] A hollow air brick 2 has a louvered front face 4 and an open rear face 6. The front face is divided into three sections with inclined louvres 8 defining vents allowing for air flow into and through the brick in normal conditions. The brick has solid side walls 10 which may be provided with interlocking fittings. The brick is typically moulded from a plastics material such as UV stabilised polypropylene or glass-reinforced plastics material. This type of air brick is well known in the art. It will be appreciated that the invention is not limited to plastics air bricks may be adapted for cement blocks plastics blocks of different widths and therefore having more or less sections or those with no divisions at all.

[0016] The air brick has been modified by insertion of a temperature sensitive self-closing device. In the embodiment illustrated the device is a pivotal vane 30 mounted inside the air brick and driven by a self-closing mechanism or switch. The mechanism shown is a temperature sensitive bimetallic spiral coil 20 which is fitted internally of the brick adjacent a short side wall inside a coil cover 22. The pivotal vane 30 is shown in Figure 4. The vane is sized to fit within the brick and has a central pivotal axis 32 terminating in a projection 34 at one end. The other end of the axis is provided with a knub 36. Both an end of the projection 34 and the knub seat in a respective recesses 38 formed in the internal side wall to hold the vane in position. The vane has a blade 40. Each edge of the blade has two notches 42 at spaced intervals. The spacing and depth of the notches 42 is designed to match reinforcement bars or ridges 44 formed in the internal surface of the air brick as part of its moulding design. The ridges are there to support the moulding of the triple window design of the louvres on the front face of the air brick. They provide a convenient mechanism for supporting and guiding the desired movement of the vane as it pivots between a first position, where it lies parallel to the long side walls of the air brick and transverse to the front face; and a second position in which it is parallel to the front face. In the first position the vane does little to impede normal ventilation. In the second position it substantially inhibits the flow of air through the brick.

[0017] The temperature sensitive mechanism, which provides the self-closing action, is a bimetallic spiral coil 20 fitted inside the cover 22 shown in Figure 3.

[0018] The cover 22 is a flat panel 46 with a raised rear side wall 48 extending round three sides of the panel. An open front is designed to face the louvres 8 when the cover is seated against one of the shorter side walls of the brick. The panel 46 has a slot 50 with a curved end to receive the projection 34 on the end of the vane axis.

[0019] The type of coil made of flat bimetallic strip is commercially available and used, for example, in thermostats and thermometers. The bimetallic coil has an external end 60 which is bent up at 90 degrees to the remainder of the strip. The other, internal end of the strip, at the centre of the coil, is permanently fixed to the projection 34. The projection 34 is provided with a slot which conveniently receive the internal end of the strip. Other methods of fixing could also be used. As the coil expands and contracts in response to temperature, rotation of the projection and hence the vane is produced. Since the movement of the vane is constrained and guided by the inter-engagement of the notches and ridges, the vane can be made to rotate between the first and second positions.

[0020] The materials of the bimetallic strip and dimensions of the coil are chosen so that the vane is at the first position when the temperature is at an upper threshold, being a normal outdoor temperature, say 4°C or above. As the strip cools to a lower threshold, say approximately the freezing point of water 0°C, the vane moves to the second position. Therefore in such cold conditions the air brick is closed and freezing external air is prevented from entering and mixing with the warmer air in the sub-floor void. The threshold temperature and range over which closure takes place will be pre-determined as appropriate to the market where the airbrick is to be used.

[0021] The end 60 of the bimetallic coil is trapped in a slot 62 formed between the inner front face of the air brick and the edge of the side wall 48 of the cover. As the coil expands further if the temperature increases beyond the upper threshold of the coil the engagement of this end 60 with the sides of the slot prevents further rotation of the vane.

[0022] It will be appreciated that the temperature sensitive mechanism may have alternative designs. For example a snap acting bimetallic disc can be used together with a lever to amplify its movement and drive the vane. The disc can be set to "pop" at the lower threshold. The disc acts as a trigger to cause rotational movement in the vane and close off the air brick. Other temperature sensitive switches known in the art that operate at the threshold temperature can be employed.

Claims

Claims 1. A hollow air brick having a front face provided with airflow openings characterised in that the air brick further comprises a vane (30) pivotally mounted behind the front face (4) so as to be able to rotate between a first open position transverse to the front face permitting ventilation and a second closed position parallel to the front face inhibiting ventilation, and a temperature sensitive mechanism (20,22) adapted to rotate the vane to its second position when the temperature is below a predetermined threshold.
2. An air brick as claimed in claim 1, wherein the vane (30) has a projection at one end of its pivoting axis (32), and the temperature sensitive mechanism is a bimetallic coil (20) having one end (60) fixed inside the air brick and the other end connected to the projection in order to bias the vane into the first position and rotate the vane to the second position when the temperature has reduced sufficiently to contract the coil.
3. An air brick as claimed in claim 1, wherein the temperature sensitive mechanism is a snap acting bimetallic disc that acts as a trigger to cause rotational movement of the vane at the threshold temperature,
4. An air brick as claimed in any one of the preceding claims, wherein the threshold temperature is the freezing point of water.
5. An air brick as claimed in any one of the preceding claims, wherein the temperature sensitive mechanism is a switch adapted to operate at the threshold temperature.