GB2138934A

GB2138934A - Hot air recirculation system

Info

Publication number: GB2138934A
Application number: GB08407566A
Authority: GB
Inventors: George Alfred Forbes
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-04-25
Filing date: 1984-03-23
Publication date: 1984-10-31
Also published as: GB8407566D0; GB2138934B

Abstract

A hot air recirculation system for a building structure comprises an upper duct section (10) extending along an upper part of the interior of the building. Inets (12) allow warmer air to enter the duct section and a fan flows the air towards a joining duct section. Thence the air is passed downwardly into a lower duct section (17) for discharge into cooler regions of the building interior. When a smoke and/or heat detector (20) is activated, it causes actuation of a flap valve (19) which normally closes a vent passage (18) whereby the combustion products are vented outside the building structure. <IMAGE>

Description

SPECIFICATION Hot air recirculation system This invention relates to a system for recirculating hot air in a building structure, e.g. a factory, and which is preferably also capable of discharging to the ambient atmosphere products of a conflagration which could occurwithin the building structure.

In order to reduce the energy requirements of a heat source in a building structure, particularly a large internally undivided building such as a factory or a warehouse, itwould be desirable to recirculate hot air, which accumulates at upper parts ofthe building, to lower colder parts thereof to provide a more even overall temperature within the building. This could be achieved by providing fans at upper levels in the building, which are directed to cause a downdraught to recirculate hot airto lower parts of the building.

However such a system has disadvantages, one of which is that, in the case of an outbreak of fire, the fans will tend to increase the spread of smoke and hot products ofthe combustion.

According to the invention, a system for recirculating warmer air in a building structure comprises duct means adapted to receive warmer air at an upper part of a building structure and to pass such airfor discharge at a lower, colder area of the building structure. Preferably vent means to extend outwardly ofthe building structure are provided to communicate with said duct means through a control means which opens the duct means to the vent means in response to detection of combustion products in the duct means so asto discharge such products through the vent means and outwardly of the building structure.

Said control means may comprise a pivotally mounted flap valve movable between a first position in which it closes an in let to the vent means while allowing substantially unobstructed flowthrough said duct means and a second position in which it allows substantially unobstructed flowthrough said vent means while preventing flowthrough the duct means past the pointtherein where the control means is located. Said control means includes means respon sivetothe present of products of combustion in said duct means to cause movement of said flap valve from said first position to said second position thereof. Said flap means may be held in said first position by latch means and may be arranged to drip under gravity to said second position when said latch means are released.Said latch means may be controlled by temperature sensitive means andlor smoke detection means. Alternatively said control means may comprise a pivotally mounted flap valve arranged in the side of the duct means being activated by a spring controlled hinge released by either a heat sensitive and/or smoke sensitive control to divert smoke into a duct means which rises through the roof structure.

Saidtemperaturesensitive means may comprise a fusible link constituting said latch means. In other embodiments one or more smoke detector(s) could be provided, inside or outside said duct means, to detect smoke, said latch means being released in response to a signal generated by said smoke detector(s) when smoke is so detected.

Said duct means may include an upper duct section for extending generally along a roof portion of a building structure which duct section communicates at one of its ends with a further duct section which extends downwardlyto a lower part ofthe building structure. Said upper duct section may have at least one inlet in a lower portion of its wall to admitwarm air into the upper duct section. Preferably means, e.g. a fan, is provided to create a flow ofairthrough the upper duct section towards said further duct section thereby inducing additional warm air into the upper duct section at the, or each, inlet therein.

Said control means may be provided in a duct joining section which has respective branch connec tionstosaid upper duct section, said further duct section and said vent means. In such arrangements said pivotally mounted flap valve may, in said first position thereof, cover the inlet to the branch connection associated with said vent means and, in said second position thereof, extend across the interior of said joining sectionto divertflowfromthe branch connection associated with said upper duct section into the branch connection associated with the vent means.

Asystem according to the invention may incorporate a plurality of duct means as aforesaid at suitable positions in upper parts ofthe building structure.

In the drawings: Figure lisa diagrammatic representation of a hot air recirculation system in accordance with the invention; Figure 2 is a diagrammatic end view ofthe system of Figure 1; and Figure 3 is an end view along a second embodiment.

Referring to the drawings, a duct 10 is positioned along an upper part of a building structure,for example a factory, to receive hot air which accumulates thereatfor recirculation to lower levels ofthe structure. In Figure 2 the duct loins shown positioned adjacent a sloping roof section 11 ofthe building to receive hot air accumulated in an apex, or one of a number apex sections, ofthe building. The ducting 10 is perforated along its lower side at a number of positions designated 12, these perforations being covered by grills 13 which will admit hot air into the duct 10.At one end of the duct section loins located a generally cruciform joining section 14 having a pair of horizontal limbs, one ofwhich is joined to one end of the duct section 10, and the other of which is closed by a plate 15. The section 14 has a downwardly extending limb 16 which is connected to a further duct section 17 through which hot air is recirculated to lower parts of the building structure. An upwardly extending vertical limb 18 ofthe joining duct section 14 provides a vent, for a purpose to be described below, which extends through the roof line 11 and is preferably covered by a cowling 9, as illustrated in Figure 2.

The direction offlowthrough the joining duct unit 11 is controlled by a pivotally mounted flap valve 19. The flap 19 is normally held in a position across the entrance to the vent duct section 18 of the joining unit.

Howeverwhen released, the flap 19 will drop under gravitytoa position shown byadotted line in Figure 1, so as to divert gaseous, and other products flowing intothejoining section 14from duct 10, upwardly through the vent section 18 and thence to the ambient atmosphere.

Theflap valve 19 is held in its position closing vent duct 18 (as shown in solid line) by releasable latching device engageable with the free end ofthe flap valve.

Such a device may comprise a latching member associated with a solenoid for movement between a "latched" position and an "unlatched" position in whichtheflap is allowed to drop to the position shown in dotted line in Figure 1 to divertthe flow emanating from duct 10 to the vent section 18. The control device may be governed by a smoke detector20,for example located in the duct 10 as shown in Figure 1. When the smoke detector 20 detects the presence of smoke, it generates an electric signal which is communicated to the aforesaid latching device in order to cause the flap 19 to become "unlatched" and to drop to its position to divertthe flowthrough the vent duct 18.In other possible embodiments, the flap valve 19may be controlled by a temperature sensitive device, e.g. it may be held in its upper position by a fusible link which allows the valve to drop when a predetermined temperature is reached.

Figure 3 shows an alternative flap valve arrange ment.The duct 10 has a vent aperture 28 in its side wall which communicated with a vent duct section 1 8a which is L-shaped and extends through the roof 11 to discharge combustion products to the ambient atmos phere. This aperture 28 is normally closed by a hinged flap valve 21 to allow passage of hot air along the duct section 10 and thence into the downwardly extending ductsection 16. The flap valve 21 is spring biased to its "closed" position as shown in Figure 3 but is normally held in its "open" position across the aperture 28 by latch means as described above in connection with the first embodiment.When the latch means are released the flap valve 21 is moved by its spring bias to extend obliquely across duct section 10 so as to divert combustion products into the vent passage 1 8a to prevent recirculation thereof within the building structure.

Afan 21 is mounted in the duct 10 at or adjacent a closed end thereof, to create a flow of hot air through the ducttowards the joining section 14thereby inducing additional hotairthrough each entry grille 12 along the duct. Therefore in normal operation, with the flap valve 19 closing the vent duct section 18, hot airwhich accumulates at an upper portion of the building is induced into the duct 10 and caused to flow along the duct 10 through the joining unit 14 and downwardly into the vertical duct 17 for recirculation to lower levels of the building. In this way a more even overall temperature throughoutthe building structure can be achieved thereby reducing heat loading on the heating sourceforthe building. In other possible arrangements the fan 21 may be located atthe opposite end ofthe duct 10 and possibly incorporated in the joining unit 14.

In the case offire breaking out in the building structure, the products of combustion will rise towards the roof of the structure. When the products of combustion are received in the duct 10 and are caused to flow along the duct by the fan 21,th ey a re detected by the smoke detector 20 which is actuated to produce a signal to release the latching device holding the valve flap 19 wherebytheflap is allowed to drop across the central portion of the duct section 14 thereby diverting the products of combustion and the hot gases associated therewith upwardly through the vent duct section 1 8to be discharged to the ambient atmosphere.

In specific embodiments of the invention, there may be a plurality of ducts 10 along the apex of a factory roof. Indeed in a building having several apex roof portions one ormoreductsectionswill be provided in each such apex portion. When a fire breaks out beneath any one apex portion the products of combustion will collect in that apex portion and after thatapex portion is filled with the toxic products of combustion, they will then overflow into the other apex portions, if such products are not discharged to the ambientatmosphere in accordance with the present invention. Such as concentration of heat could damagethe roof structures, for example asbestos materials could crack open which would then increase the supply of oxygen to supportthe combustion within the building structure. Howeverthe provision of duct sections in accordance with the invention in the apex portions of the roof, will assist in safely discharging the flames, intense heat and toxic smoke created bythe fire, to the surrounding atmosphere.

The invention therefore provides a means of achieving a fuel saving in a building structure coupled with the provision of means for reducing fire hazards by safely discharging to ambient atmosphere the products of a conflagration which breaks out within the building structure.

Claims

1. A system for recirculating warmer air in a building structure comprising duct means adapted to receive warmer air at an upper part of a building structure and to pass such airfor discharge ata lower, colder area ofthe building structure.

2. Asystem according to Claim 1 wherein vent means to extend outwardlyofthe building structure are provided to communicate with said duct means through a control meanswhich openstheductmeans to the vent means in response to detection of combustion products in the duct means so as to discharge such products through thevent means and outwardly of the building structure.

3. Asystem according to Claim 2 wherein said control means comprise a pivotally mounted flap valve movable between a first position in which it closes an inletto the vent means while allowing substantially unobstructed flowthrough said duct means and a second position in which it allows substantially unobstructed flow through said vent means while preventing flowthrough the duct means past the pointtherein where the control means is located.

4. Asystem according to Claim 2wherein said control means includes means responsive to the presence of products of combustion in said duct means to cause movement of said flap valve from said first position to said second position thereof.

5. Asystem according to Claim 3 wherein said flap valve means is held in said first position by latch means.

6. Asystem according to Claim Swherein said flap valve means is arranged to drop under gravity from said first position to said second position when said latch means are released.

7. Asystem according to Claim Swherein said flap valve means are resiliently biassed to move from said first position to said second position when said latch means are released.

8. Asystem according to Claim Swherein said latch means are controlled by temperature sensitive means and/or smoke detection means.

9. Asystem according to Claim 8wherein said temperature sensitive means comprise a fusible link constituting said latch means.

10. Asystem according to Claim 8wherein at least one smoke detector is provided, inside or outside said duct means, to detect smoke, said latch means being released in response to a signal generated by said smoke detector when smoke is so detected.

11. A system according to Claim 1 wherein said duct means includes an upper duct section for extending generally along a roof portion of a building structure which duct section communicates at or adjacent one of its ends with a further duct section which extends in a downward direction to a lower part ofthe building structure.

12. A system according to Claim 11 wherein said upper duct section has at least one inlet in a lower portion of its wall to admitwarm air into the upper duct section.

13. A system according to Claim 11 wherein means are provided to create a flow of airthrough the upper duct section towards said further duct section thereby inducing additional warm air into the upper duct section atthe, or each inlettherein.

14. Asystem according to Claim 2 wherein said duct means includes an upper duct section for extending generally along a roof portion of a building structure which duct section communicates at or adjacent one of its ends with a further duct section which extends in a downward direction to a lower part of the building structure and said control means are provided in a ductjoining section which has respective branch connections to said upper duct section, said further duct section and said vent means.

15. A system according to Claim 14wherein a pivotally mounted flap valve means in a first position thereof, covers the inletto the branch connection associated with said vent means and, in a second position thereof, extend across the interior of said joining section to divertflowfrom the branch connection associated with said upper duct section into the branch connection associated with the vent means.

16. Asystem according to Claim 1 having a plurality of duct means as aforesaid located to extend from discrete positions at upper parts of a building structure.

17. Asystem for recirculating warmer air in a building structure, the system being substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 and 2 or Figure 3 of the accompanying drawing.