GB2138124A - Ventilator - Google Patents

Abstract

A ventilator for incorporation in a window frame or structure surrounding a window frame includes heat-exchange surfaces (26,28) providing for exchange of heat between air extracted from an associated room and air drawn into that room. <IMAGE>

Description

SPECIFICATION Ventilator This invention relates to ventilators such as are used in conjunction with or adjacent to window openings of houses and other buildings.

Over a period of years the standards of comfort in houses, offices and other buildings has increased substantially because ofthe use of central heating systems, but more recently the relatively rapid in crease in energy costs has resulted in the need to conserve the heat which provides the desirable additional comfort. ltfollowsfrom thisthatmany buildings are provided with double glazing and every effort is made to minimise heat losses by sealing cracksthroughwhich heated air can readily escape.

While highly desirable from the viewpoint of thermal conservation, the near hermetic seal of rooms and other spaces leads to inconvenient and some times unpleasantside-effectsfrom excessive humid ity and inadequateoxygen supplies.

Ventilators,whetherforced draught or natural draught have been proposed to overcome this prob lem, but the advance provided in relation to merely openinganopenabtelightisnotvervgreat In particularthe heat loss can be substantial and draughts are sometimes produced in the room with resultantdiscomfortforsomeorall of the occupants.

According to the present invention there is provided a ventilatorfor incorporation in a windowframe or structure surrounding a windowframe including heat exchange surfaces providing for exchange of heat between air extracted from an associated room and air drawn into that room, or alternatively air extracted from the room can be passed through the heat exchanger and recirculated to the room, the heat exchange surfaces serving to condense out a propor- tion ofthewatervapourintheextracted air.

The heat-exchange is preferably of counter-flow type and may conveniently extend within a window frame over a height orwidth dimension enabling a substantial heat exchange surface to be traversed by the flows. Where large mass flows are required at low velocities the heat-exchanger may be incorporated both in the vertical and horizontal members ofthe frame or adjacent structure. The heat-exchanger may be made of extruded aluminium or aluminium alloy sections and may be treated to ensure corrosion does not arise in one or other pass or both passes of the heat-exchanger.

Controls may be provided to exclude fresh air being drawn in from the outside when conditions are exceptionally cold but air can nevertheless be circu 3 lated through the heat-exchanger in order to conde nse out excessive moisture which is drained to the outside. Means may be provided in the form of baffles to prevent rain being drawn in through the fresh air intake(s).

The invention will now be described, byway of example only, with reference to the accompanying diagrammatic drawings in which: Fig. 1 is a perspective view of a window assembly in which the sub-framethereof incorporates a ventilator in accordance with the invention; Fig. 2 is a highly diagrammatic view showing the heat-exchange aspect of the ventilator; Fig. 3 is a diagram illustrating a multi-pass heatexchanger which can be incorporated in the ventilator; and Fig. 4 is a cross-section of the ventilator heatexchanger illustrated in Figure 3.

Referring nowtothedrawingsthewindowframe of the assembly illustrated in Figure 1 may be of conventional-type of wood, aluminium, aluminium alloy, steel or plastics butthe sub-frame 12 incorporates in each vertical member a heat-exchange system 14 having extraction vents 16 nearthe upper end and fresh air inlets 18 nearthe lower end. Grills or louvres will prevent or reduce the intake of rain through the inlets 18.

Figure 2 illustrates in a highly diagrammatic manner the heat-exchange system 14 and in addition to the parts shown in Figure 1 shows the inlet 20 to the room from the ambient atmosphere and the outlet 22 from the room for stale air. An additional outlet 24 is provided for condensation which is liable to drain from the hot pass 26 of the heat-exchanger. The cold pass is denoted by 28 and may also include provision for drainage in the eventthat any rainwater gains access through the inlets 18.

As will be appreciated the diagrammatic showing of Figure 2 is unlikely to be adequate from the efficiency standpoint and an acceptable exchange of heat from the stale air to the fresh air can best be achieved by the construction illustrated in Figures 3 and 4. In this embodimentthe principle remains the same as in Figure 2 butthe hot and cold passes ensure successive traverses, the one by the other, so that the heatexchange can be as good as 70 per cent of the theoretical which is possible, or in other words a 70 per cent efficiency.

As is particularly apparent in Figure 4the heatexchangermaytaketheform of an extrusion or sheet metal fabrication having a rectangularwave-form in cross-section. Headers (not shown) will distribute the inflow and outflow in such a way that alternate channels provide forthe passage of the stale air and the fresh air. The flow paths through the hot and cold passes will both be of elongate sinuous form. Thus, before fresh air actually enters the room through the opening 18 it will have passed over a heat-exchange surface equal to three times the height of the window frame.

Afan will be provided in both the hot pass and cold pass ofthe heat-exchanger conveniently at or adjacent the headers and a shutter may be provided to close off the air inlets 18from the ambient atmosphere The drawing(s) originally filed was (were) informal and the print here reproduced is taken from a later filed formal copy.

The claims were filed later than the filing date with the period prescribed by Rule 25(1) of the Patents Rules 1982.

so that stale, humid, air can be recirculated through the hot pass which will have the effect of condensing out excessive moisture.

Although the heat-exchanger has been illustrated as incorporated in the vertical members of the sub-frame it is also possible to incorporate the heat-exchanger in the horizontally extending member of the sub-frame, particularly since this will normally provide for a longer heat-exchange pass with consequent im proved efficiency. As is apparent in Figure 4the preferred sub-frame itself is made offoamed plastics material which has a high thermal insulating value and the incorporation of the heat-exchanger will also serve a structural purpose since the extruded heatexchanger matrix will have appreciable strength in bending and if incorporated in the vertical members it will have appreciable compressive strength.Since the framed plastics itself has appreciable strength the heat-exchanger matrix will not, because of wherein forcement aspect result in frame members of larger cross-section than conventional.

In the description hereinbefore setforth in relation to the drawings the heat-exchanger has been proposed to be incorporated in a sub-frame of a window but in instanceswhereawindowisnottobeinstalled for the firsttime or exchanged as a whole, the heat-exchanger of the ventilator may be made as a separate unitfor incorporation asa structure replacing one ortwo courses of brickwork immediately above or below the respective horizontal member of the sub-frame assembly.

Calculations indicate that for a heat-exchange surface area offoursq.m. a heat-exchange recovery of upto 70 per cent can be achieved and this would allow 1 to 2 air changes per hour in an average size of domestic room.

It will be appreciated thatthe heat-exchanger illustrated in the diagrammatic drawings accompanying this application can be modified furtherto improve the heat-exchange coefficient and in one construction 25 laminations based at the edges by plastics spacers provides for a good heat-exchange coefficient.

Claims (8)

1. Aventilatorforincorporation in a windowframe or alternatively a structure surrounding a window frame, theventilator including heat exchange surfaces providing for an exchange of heat between air extracted from an associated room and air drawn into that room, means being provided selectively to extractairfromthe room through the heat exchanger and return to the room, the heat exchange surfaces serving to condense out a proportion of water vapour in the extracted air whichever mode of operation is selected.

2. Aventilator incorporated in a windowframe or structure surrounding a window frame comprising heat exchange surfaces providing for exchange of heat between air extracted from an associated room and air drawn in from the ambient into that room.

3. Aventilatoraccording to claim 1 or claim 2 comprising fan means for assisting circulation through the heat exchange surfaces.

4. Aventilator according to any one of the preceding claims wherein the heat exchange surfaces operate on a counterflow principle.

5. Aventilatoraccordingto any one of the preceding claims wherein the heat exchange surfaces extend over the height of the window frame or other structure.

6. Aventilator according to any one of claims 1 to 4 wherein the heat exchangesurfaces extend both over a height and width dimension of frame or other structure.

7. Aventilatoraccording toanyone of the preceding claims wherein the heat exchange surfaces are provided on extruded aluminium craiuminium alloysectfons treated to protectthie-m from. corrosion.

8. Aventilator incorporated in a windowframe or structatesurrounding awindowframesubstantially as hereenbefore described with referencetothe aceompanying drawings.