The present invention relates to a heating and ventila¬ tion system of the kind defined in the preamble of Claim 1.

It is found difficult in systems of this kind to adjust an incoming fresh-air flow to a temperature which will provide the various rooms of a building or living apartment with draughtfree ventilation at a comfortable temperature and to maintain said fresh-air flow at the adjusted temperature.

The present invention provides an extremely simple system of the aforesaid kind which fulfills the high comfort requirements placed thereon. This is achieved despite the fact that the system can be operated with low temperature energy in its true meaning, even at extremely low ambient temperatures, namely with the aid of an incoming flow of liquid whose input temperature is not more than about 7°C above the desired room temperature. Thus, the return pipes of a district heating network can be used advantageously for heating apartment buildings, and solar energy can also be used as a significant supplement to the system. When ambient temperatures are high, the system will function automa¬ tically as a ventilation system with fresh-air cooling.

This has been achieved in accordance with the invention through a combination of the devices and arrangements recited in the introduction, including floor-mounted heating loops or the like, wherein a control means is provided for maintaining the input temperature of the liquid delivered to the system and to the floor heating loops at a temperature which is at most 7°C, preferably

at most 4°C above or beneath the desired room tempera¬ ture when respectively heating or cooling the locality concerned, and wherein the fresh-air inlet devices are configured with heat exchange surfaces which are so large, and therewith generate a temperature difference relative to a given room temperature which is so low that said devices are self-stabilizing with respect to the temperature of the fresh air flowing into the room and attemperate said air to a temperature which differs by at most a few degrees from the desired room tempera¬ ture.

The inventive heating and ventilating system attempera- tes the incoming fresh air to a temperature close to the desired room temperature with the aid of a heat ex¬ changer whose heat-exchanging surfaces maintain a temperature which differs by only some few degrees from the temperature of the attemperated fresh air, irres¬ pective of the ambient air temperature. When the am- bient air temperature rises from its original low values to the same temperature values as the heat- exchanger temperature, the heat transfer decreases to zero and if the ambient temperature increases still further, the heat exchanger will cool the incoming fresh air. This obviates the need to adjust the tempe¬ rature of the fresh air in connection with its intro¬ duction into the room or locality concerned. The whole of the apartment building can be served by one ambient- temperature sensing control device which controls the input temperature within the aforesaid limits.

The invention will now be described in more detail with reference to the accompanying drawings, which illu¬ strate schematically an exemplifying embodiment of an inventive heating and ventilating system and in which

Figure 1 is a cross-sectional view of a two-storey building;

Figure 2 is a cross-sectional view of a fresh-air inlet and fresh-air attemperating device and shows adjoining parts of an outer wall fitted with a window;

Figure 3 is a principle diagram illustrating the con¬ nection of the heating and ventilating system to a central heating system; and

Figures 4a and 4b are diagrams which show the tempera- ture conditions in a room as a function of the hours of the day and of the ambient temperature respectively.

Figures 1 and 2 illustrate a building of modern con¬ struction having good insulation and being of robust construction, which is necessary if the inventive system is to be used to the best possible effect. Formed in the external wall 1, beneath windows 2, are through-passing openings 3 which are lined with sheet- metal walls, wherein the bottom wall 4 is inclined slightly outwards so that- any water condensation that may form can drain away from the building, as will best be seen from Figure 2. A heat exchanger unit 5 is inserted into the opening 3, from within the building, and is connected to pipes 16 which conduct flowing, attemperated liquid to and from the pipes 7 of the heat-exchanger unit, these pipes being in good thermal contact with the heat-exchange plates 8 of said unit. An exchangeable sound and particle filter unit 9 is inserted into the opening 3 from outside the building and is covered with an outwardly openable fine-mesh grid 10. A fine-mesh filter 11, for instance a pollen filter, is mounted at the opposite end of the opening.

The inventive system also includes floor-mounted heat- ing loops 13. similar to the heat-exchanger unit 5 of

the fresh-air intake device, these heating loops are connected to a coupling box 14 which houses stop valves 15 and a control valve 16, as illustrated in Figure 3. The floor-heating loops and the heat-exchanger unit are connected by means of the valves in the coupling box to an input pipe 17 and a return pipe 18 to which liquid is supplied from a central heating station 19. The central heating station is supplied, in turn, from an appropriate low-temperature network, which may advanta- geously be the return line 20 of a district heating system. A simple control device 21 functions to main¬ tain the temperature of the liquid medium in the input pipe 17 at a value which is contingent on ambient temperature, as illustrated in Figure 4a (which illu- strates the conditions prevailing at an ambient tempe¬ rature of ± 0°C) and Figure 4b.

In order to obtain uniform distribution of the tempera¬ ture in a confined apartment or flat, or like locality, and to obtain draughtfree ventilation, the system includes a suction device 25 which communicates, for instance, with the cooker hood 26 in a kitchen and an exhaust air valve 27 fitted in a bathroom for instance. Any partition walls that may be present can be provided with connecting channels 28, preferably in a manner such as to obtain a sound-trap at the same time.

The suction device 25 is constructed to provide a basic ventilation of the order of about 15 1/sec through the fresh-air intake device 5,9, which is also constructed to throttle the air flow slightly, so as to obtain a pressure drop of 15 Pa.The output of the suction device 25 can be adjusted to some extent by means of a control device 29.

A typical example is one in which a room temperature of +20°C is obtained at a basic ventilation and an ambient temperature of -20 ^β C when the input temperature of the incoming liquid has a temperature as low as 26-27"c.