GB2180925A - Ventilators - Google Patents

Abstract

The ventilator for dwellings or other buildings comprises a rectangular section duct of inner and outer telescopic parts 10, 12 made of rigid PVC. The inner part 10 has two internal inclined flanges 18 at opposite sides on which is supported a rigid rectangular, parallelepiped porous body of mineral wool. The body is clamped at its upper end between the top wall of the duct and the flanges 18. The body allows water vapour to diffuse outwardly from the interior of the building; it also resists air flow through the duct reducing the speed of through air-flow to 20% to 50% of external air speed, depending on the speed. The ducts are fitted in openings through opposite external walls near the ceiling in ground floor rooms e.g. kitchen. Condensation is prevented without an excessive increase in air flow through the building. The telescopic duct can be fitted to walls of different thicknesses. <IMAGE>

Description

SPECIFICATION Ventilation means The invention relates to ventilation means.

It is already established that the basic ventilation requirementfora dwelling, for example, is between 1/2 and 3/4 volume airchange per hour. This isto allow the internally-generated water vapourto es- cape to the exterior, to control odours and to provide combustion airforfuel-burning appliances. Energyconservation measures in dwellings, primarilyto reduce space-heating bills, have resulted in the extensive use ofdraught-excluderstrips and a considerable reduction in the opening of windows during the space-heating season. The resultant reduction in the supply of fresh air has caused a considerable increase in internal condensation. This occurs when the internal water content ofthe air rises to above its dew-pointtemperature.This is usually at 70% relative humidityforinternal airtemperatures of between 16 and 24 Celsius when the dew-point temperature is between 10.5 and 18.2 Celsius. The avoidance of condensation requires an increased ventilation rate, resulting in increased heat consumption and higher energy bills.

The object of the invention is to provide ventilation means which allows internal watervapourto escape from a building to the exterior by the action of differential watervapour pressure and air movement, but in which the rate of heat loss by airflow is limited by a porous barrier permitting passage ofwater vapour, so that the risk of condensation is reduced without severe heating consumption penalty.

Ventilation means according to the invention comprise a porous body of water-resistant material and structure defining an opening, a path for airflow passing through both the body and the opening, and the body presenting resistance to airflow along said path and enabling watervapourto diffuse th rough the pores ofthe body along said path.

Preferably, the body comprises inorganicfibrous material.

It is particularly preferred thatthefibrous material is mineral wool.

There are many possible ways of arranging the porous body in relation to the opening, for example by mounting the body directly on the building structure, either outside or inside the opening provided in the structure. However, it is preferred thatthe structure defining the opening is a duct.

Embodiments ofthe invention will now be described with reference to the accompanying drawings in which Figures 1 and 2 are end elevations of ventilating means in the form of a duct showing a porous body inside the duct; Figure 3 is a vertical longitudinal section on the line Ill-Ill in Figure 1; and Figures4 and 5 are respectively ground and first floor plans of a dwelling provided with ventilation means according to the invention.

Figures 1 to 3 showa two-part duct made up of a longer part 10 telescopically insertable in a shorter part 12. The duct can be adjusted in length from 350 millimetres to 275 mm to suitvarious cavity wall thicknesses typically between 325 mm and 275 mm.

Typically the part 10is inserted from the outside of the external wall ofthe building andthe part 12from the inside. The duct parts are of rectangular trans- verse cross-section, the end faces 14, 16 of the parts 10,12 respectively correspond to standard external metal louvre and internal cast, plaster louvre sizes.

The parts 10,12 are moulded from rigid non-metallic material such as polyvinylchloride, forexample.

Typically, the thickness of the walls of the parts is 3 mm.

The longer part 10 hastwointernal,coplanar flanges 18which extend away from respective side wall faces ofthe part 10. The flanges 18 are inclined to the lengthwise direction of the duct.

The longer part 10 carries within it a porous rigid body 20 offibrous mineral wool. Typically, the body 20 is of material available from Rockwool Limited, Pencoed, Bridgend, Mid-Glamorgan, CF35 6NY.

The body 20 is generally of rectangular parallelepiped shape and has its side faces 22 abutting respective inner, opposed faces 23 of the duct part 10. The body 20 rests on the flanges 18 so that its majorfaces 24 are inclined. The upper end ofthe body 20 is slightly chamfered at its upper majorface 24so that the end of the body20 effectively clamped between the flanges 18 and the top wail of the duct part 10.

The duct parts 10 and 12 define an opening extending lengthwise through the duct. A path for airflow passes through both the pores of the body 20 and the opening through the duct. The body 20 presents re sistance to air flow along that path . The body 20 also enables water vapour to diffuse along the path through the body 20 bythe action of differential water vapour pressure. Typically, for example, the material ofthe body 20 has a density of 23 to 32 kilograms per cubic metre. Its resistance to airflow is such that it reduces air speed to some 50% to 20% of the speed of air outside the building, depending on the speed. It has awatervapourdiffusion rate of 0.14 kilogram per metre per second pergigapascal.

When tested in accordance with British Standard 2972 the maximum water absorption ofthe material from the air is approximately 1.0 volume per cent.

The material is water-resistant, non-combustible and will not rot or attract or harbourvermin or insects.

Typically the body 20 is some 50 mm thick between the major faces 24.

The transverse cross-section of the part of the path ofairflowthrough the body 20 is obviously greater than the transverse cross-section ofthe remainder of the path within the duct.

The ducts are typically installed in external walls of a building such as a dwelling. In each case, the duct is preferably installed nearto the ceiling in a ground floor room. Preferably, one duct opens to the kitchen and another opens from a room atthe opposite side ofthe building,forexample.

Atypical layout of ducts in a small dwelling in which field trials have been conducted is shown in Figures 4 and 5. Fourducts of the kind described with reference to Figures 1 to 3 are indicated at 30,32,34 and 36 in Figure 4, the ground floor plan. In each of the other rooms, a slot ventilator such asthetype known as "Greenwood-Airvac" available from Greenwood-Airvac Limited, Brookside Industrial Estate, Rustington, Littlehampton, Sussex, was provided atthewindow head.

Each duct can pass air either inwardly or outwardly depending on ambient conditions especially wind direction.Watervapourdiffuses outwardly most rapidly atthe or each ductthrough which the airflow is outwards. However, outward diffusion of vapour continuesunderconditionswhere airflowis nil and even to some extent in ducts through which airflow is inward.

In the dwelling represented in Figures 4 and 5, very severe condensation was originally present. After the installation oftheventilation means in accord ance with the invention, the structure ofthe dwelling progressively dried out even during a winter season.

Athermohygrograph was installed and gave a record showing that (i) peaks ofwatervapour generation first occurred then rapidly declined; and (ii)the weekly average internal air temperature was about 20with relative humidity of 52% and a dew point temperature of 10.5 C. Only limited periods of excessive humidity occurred and condensation was intermittent only and limited to the single-glazed windows.

In modifications (not shown) the body is outside the duct; orthe duct is dispensed with, the body being mounted in an opening in the wall of the building; or outside the opening. For example, in a solid wall,the body may be mounted in an opening withoutthe use of a duct, the wall structure defining the respective opening.

Claims (13)

1. Ventilation means comprising a porous body of water-resistant material and structure defining an opening, a path for airflow passing through both the body and the opening, and the body presenting re sistancetoairflowalongsaid path and enabling watervapourto diffuse through the pores of the body along said path.

2. Means according to Claim 1, in which the body comprises inorganicfibrous material.

3. Means according to Claim 2, in which the fibrous material is mineral wool.

4. Means according to any preceding claim, in which the body is a rigid body.

5. Means according to any preceding claim, in which said structure is building structure.

6. Means according to Claim 5, in which said structure is afirstwall of said building and said building has second ventilation means also according to Claim 1 in which the structure is a second wall ofthe building.

7. Means according to any preceding claim, in which the body is within the opening.

8. Meansaccordingto anyclaim ofciaims 1 to6, in which the body is outside the opening.

9. Means according to any preceding claim, in which the transverse cross-section of the part of said path through the body is greaterthan the transverse cross-section ofthe remainder of said path.

10. Means according to claim 1,2,3 or4, in which said structure is a duct.

11. Means according to Claim 10, in which the cross-section of the duct transverse to the lengthwise direction thereof is rectangular and in which the body is a rectangular parallelepiped having its major faces inclined to said direction and having its side faces abutting respective opposed innerfaces ofthe duct.

12. Means according to Claim 10,inwhichthe duct has two internal coplanarfianges inclined to said direction and extending inwardly each from a respective one of said opposed innerfaces ofthe duct, the body being supported on the flanges.

13. Ventilation means according to Claim 1 sub stantially as described herein with reference to the accompanying drawings.

13. Means according to Claim 1,substantiallyas herein described with reference to Figures 1 to 3 of the accompanying drawings.

14. Means according to Claim 1 installed in a building substantially as described herein with reference to the accompanying drawings.

Amendments to the claims have been filed, and have the following effect: *(a) Claims 1-14 above have been deleted *(b) New ortextually amended claims have been filed asfollows:

1. In a building, ventilation means comprising a porous body of water-resistant material and structure defining an opening which communicates with onlythe outside and inside of the building, a pathfor airflow passing through both the body and the opening,the length ofthe part of said path through said body being a minor proportion of the total length of said path, and the body presenting resistance to air flow along said path and enabling watervaporto dif- fuse through the pores of the body along said path.

2. Ventilation means according to Claim 1,in which the body comprises inorganic fibrous material.

3. Ventilation means according to Claim 2, in which the fibrous material is mineral wool.

4. Ventilation means according to any preceding claim, in which the body is a rigid body.

5. Ventilation means according to any preceding claim, in which said structure isafirstwall ofsaid building and said building has second ventilation means according to any preceding claim in which the structure is a second wall ofthe building.

6. Ventilation means according to any preceding claim, in which the oreach body is within the respective opening.

7. Ventilation means according to any claim of claims 1 to 5, in which the or each body is outside the respective opening.

8. Ventilation means according to any preceding claim, in which the transverse cross-section ofthe part of said path through the or each body is greater than the transverse cross-section ofthe remainder of said path.

9. Ventilation means according to any preceding claim, in which said structure, or each structure, comprises a duct.

10. Ventilation means according to any claim of Claims 1 to 6, or Claim 8 or9 as dependent on any claim of Claims 1 to 6, in which the cross-section of the or each ducttransverseto the lengthwise direc tionthereofisrectangularand in which the respective body is a rectangular parallelpiped having its majorfaces inclined to said direction and having its side faces abutting respective opposed innerfaces of the duct.

11. Ventilation means according to Claim 10, in which the duct or each duct has two internal coplanar flanges inclined to said direction and extending inwardly each from a respective one of said opposed innerfaces of the duct, the respective body being supported on the flanges.

12. Ventilation means substantially as herein de scribed with reference to Figures 1 to 3 of the accompanying drawings for use according to Claim 1 in a building.