WO1989009369A1

WO1989009369A1 - An air heating and ventilation system

Info

Publication number: WO1989009369A1
Application number: PCT/FI1989/000053
Authority: WO
Inventors: Heikki Andersson; Matti Haapakoski
Original assignee: Imatran Voima Oy
Priority date: 1988-03-29
Filing date: 1989-03-22
Publication date: 1989-10-05
Also published as: FI881467A; AU3438089A; FI85763B; FI881467A0; FI85763C

Abstract

This invention relates to an air heating and ventilation system, comprising a supply air duct (1); an exhaust air duct (2); a heat recovery unit (LTO) between the supply and exhaust air ducts (1, 2) for transferring heat from the exhaust air into the supply air; a heat storing unit (MV) for storing heat and for delivering it into the air passed therethrough; and a damper (SP) in the supply air duct (1) for passing air partly directly and partly through the heat storing unit (MV) into room spaces (3, 4, 5, 6) to be heated. In the invention, in order to enable efficient adjustment of temperature separately in each room space within the air heating system having the heat storing unit (MV) as the main source of heat, the damper (SP) is controlled in such a manner that the heat storing unit (MV) supplies the heating system with basic heat while adjustment heat is supplied separately for each room space by duct heating units (KL4, KL5, KL6) provided in a supply air distribution duct (7) and controlled by thermostats (TE4, TE5, TE6) for each room space, respectively.

Description

An air heating and ventilation system

The invention relates to an air heating and ventilation system, comprising a supply air duct; an exhaust air duct; a heat recovery unit between the supply and exhaust air ducts for transferring heat from the exhaust air into the supply air; a heat stor¬ ing unit for storing heat and for delivering it into the air passed therethrough; and a damper in the supply air duct for passing air partly directly and partly through the heat storing unit into room spaces to be heated.

One air heating and ventilation system is dis¬ closed in Finnish Patent Specification 59664. The sys- tern is for a major part of the type described above and it is used for heating a block of flats in such a manner that the amount of heat to be supplied can be controlled separately on each side of the building. However, this system does not comprise any heat stor- ing units, and it is not particularly suitable for the heating of a detached house, for instance. On the other hand, the use of a heat storing unit as a source of heat in an air heating system is known from Finnish Patent Application 851630, for instance. Therein the heat storing unit is a unit assembled of soapstone, which is quite suited for the purpose when the tem¬ perature limit is taken into consideration, that is, the fact that if the temperature of soapstone exceeds 600°C, the carbonates contained in the stone begin to decompose and the stone begins to become brittle. Other heat-storing materials of the known type include concrete, water, oil and masonry tile constructions. A drawback common to all these materials is that they require a lot of space and that the installation of the system is laborious. Normally a single electrical- ly heated heat storing unit of one of the different types has been positioned in each room space to be heated, which results in unreasonably high costs for the system. On the other hand, problems are involved in the use of a single heat storing unit as a central heat source of an air heating system mainly because it has not been possible to any greater degree to take into account the varying heat requirements of the dif¬ ferent room spaces. Therefore the temperature may rise unreasonably high in some room spaces while it is too low in the others. A further problem of conventional air heating systems is that they often require circu¬ lation of air so that the air to be supplied into the rooms is obtained partly from outside the building and partly from the room spaces, as a result of which im¬ purities formed in one room space tend to spread to the other room spaces in spite of filters used. As a consequence, air circulation systems of this type do not necessarily meet the modern high requirements con- cerning indoor climate, especially as far as the purity of the air is concerned.

The object of the present invention is to pro¬ vide an air heating system which also serves as a ven¬ tilation system and which avoids the above-mentioned problems of conventional air heating systems.

This object is achieved by means of an air heating and ventilation system according to the inven¬ tion, which is characterized in that the damper is controlled in such a manner that the heat storing unit supplies the heating system with basic heat while ad¬ justment heat is supplied separately for each room space by duct heating units provided in a supply air distribution duct and controlled by thermostats pro¬ vided for each room space, respectively. In this way the heat storing unit can be used for the generation of the basic heat for the air heating system even though it cannot be used for controlling the tempera¬ ture separately in each room space. This is because the basic heat is adjusted so that a sufficient tem- perature can be obtained by means of it only in some well-protected spaces whereas the basic heat does not wholly fulfill the heat requirement in all the other spaces in normal use. Therefore, the electrically heated duct heating units controlled by the room space thermostats supply additional heat for each room space, thus enabling the temperature in each indi¬ vidual room space to be adjusted separately. In order to achieve such an adjustment in the system, it is preferable that the damper of the supply air duct is controlled by means of a thermostat disposed in a suitable room space to be heated. This suitable room space may be, e.g., a space which is positioned in the middle of the building and from which relatively little heat is dissipated into the surroundings so that it is unaffected by rapid changes caused by weather. Furthermore, it is to be preferred that the storing of heat in the heat storing unit is controlled on the basis of the outdoor temperature, so that the amount of heat stored therein would fulfill the heat requirement while power supply to the heat storing unit is disconnected. In a normal case, when using electrical energy, for instance, heat is stored in the heat storing unit merely at night when the price of electrical energy is substantially lower than at the daytime. This practice is advantageous both to the consumer and the producer of electrical energy since it does not rise the daily consumption peak of elec¬ trical energy.

In the following the air heating and ventila- tion system according to the invention will be de- scribed in more detail with reference to the attached drawing, whose figure illustrates schematically the structure of the air heating and ventilation system according to the invention. The air heating and ventilation system accord¬ ing to the invention shown in the figure comprises a supply air duct 1; an exhaust air duct 2; a heat re¬ covery unit LTO between the supply and exhaust air ducts 1 and 2 for transferring heat from the exhaust air to the supply air; a heat storing unit MV for storing heat and delivering heat to the air passed through the heat storing unit; a blower 15 positioned in the supply air duct 1; and a damper SP for introducing supply air partly directly and partly through the heat storing unit MV into room spaces 3, 4, 5 and 6 to be heated. A filter 8 is provided in the supply air duct 1 for filtering off impurities from fresh outdoor air, and a blower 9 for introducing fresh air into the system. The function of the filter 8 is to prevent the entrance of impurities into the room spaces to be heated and the contamination of the cells of the heat recovery unit LTO. A filter 10 is similarly provided in the exhaust air duct 2 before the heat recovery unit for preventing impurities from entering it. After the heat recovery unit, there is further provided, in the exhaust air duct 2, an ex¬ haust air blower 11 for removing a sufficient amount of air from the spaces to be heated. By controlling the blowers 9 and 11, the system according to the in- vention can also function as a ventilation system meeting the requirements concerning ventilation. It thus should be possible to control these blowers ac¬ cording to the need of ventilation so that the venti¬ lation can be kept at a relatively low level when the room space to be heated is not occupied and corre- spondingly at a higher level when the room is occupied. This control of the ventilation is not con¬ tradictory to the air heating function of the same system, because a major part of the heat contained in the exhaust air is recovered by means of the heat re¬ covery unit LTO. It is further to be noted that the air heating system according to the invention is con¬ trolled mainly by adjusting the temperature of the supply air, so that the amounts of air can be kept within limits advantageous for the ventilation pur¬ poses, thus avoiding unnecessary heat losses. In order to prevent unreasonably great heat losses with this kind of combined ventilation and heating system even at very low subzero temperatures, the system is further provided with a circulation duct 12 com¬ prising a damper KSP and a filter 13. Through the cir¬ culation duct 12, it is possible to suck part of the air for the supply air duct 1 by means of the blower 15 from the room spaces where the air is already warm. The proportion of the recirculation air can be adjusted by means of the damper KSP.

The core of the air heating system according to the invention is formed by the heat storing unit MV, which in practice can be of any known structure. How- ever, it is preferable that this unit is as small as possible and insulated to such an extent that no sig¬ nificant heat losses into the surroundings take place through conduction. It is further to be preferred to provide a tap water spiral KV in connection with the heat storing unit for producing warm tap water. In the figure, an electrical resistor SV is connected to the circuit of warm tap water. The function of the elec¬ trical resistor is to produce warm water when the heating is off or when the heat storing unit is not able to heat the water sufficiently. The storing of heat in the heat storing unit is controlled by means of a control unit TCI on the basis of a thermostat TE1 sensing the outdoor temperature. In this way the amount of stored heat is sufficient in view of the heat requirement of the room spaces to be heated in the daytime when the heat storing unit is disconnected from the mains. The same control unit TCI also con¬ trols the damper KSP of the circulation duct 12 by means of a motor 14, so that this damper can be ar- ranged to respond to the outdoor temperature in such a manner that is opens, e.g., at extremely low subzero outdoor temperatures only.

By means of the damper SP disposed in the supply air duct 1, supply air is introduced with the blower 15 partly through the heat storing unit MV and partly directly into a supply air distribution duct 7. In this way the temperature of the supply air in the distribution duct 7 will be such as desired. The damper SP is controlled by a control motor M which in turn is controlled by a control unit TC2. The control unit TC2 operates partly in response to the tem¬ perature measured from a suitable space by means of a thermostat TE3 and partly in response to the tempera¬ ture measured from the supply air distribution duct 7 by means of a thermostat TE2. The space 3 wherein the thermostat TE3 is positioned is chosen so that the temperature prevailing therein can be regarded as a basic temperature suitable for all the spaces to be heated. In practice, the space 3 is such that its heat requirement is relatively small and, in practice, smaller than that of the other spaces. Further, the temperature of the space may be slightly lower than that of the normal room spaces to be heated. The room space 3 could be e.g. a room reserved for the storage of clothes. When the basic heat to be supplied into the heat distribution system is determined as de¬ scribed above, the amount of heat supplied into the room spaces 4, 5 and 6 to be heated is not sufficient to satisfy the entire heat requirement of the spaces. This situation is created with purpose because the re¬ quired amount of additional heat can be supplied by means of electrically heated duct heating units KL4, KL5 and KL6 provided for respective room spaces and controlled by thermostats TE4, TE5 and TE6, re- spectively. In this way the temperature of each indi¬ vidual room space can be easily set separately, and the structural features of the different rooms, such as a great number of windows or a location on the southern side of the building, can be taken into ac- count.

Due to the structure and operating principle of the air heating and ventilation system according to the invention, it does not normally require circula¬ tion of air, that is, it is not necessary to reheat slightly contaminated air and recirculate it in the air distribution duct into the room spaces to be heat¬ ed. This is a major advantage to be obtained by means of the system according to the invention. For this reason as well as for the other structural features of the system according to the invention, it can be en¬ sured that the indoor climate and ventilation provided in a building by means of the system meet all official regulations and instructions. This is achieved by means of the single, integrated system according to the invention, which eliminates the need of two separ¬ ate systems for effecting ventilation and heating. This involves considerable savings in costs both at the planning and installation stage. In addition, the system according to the invention enables the use of the heat storing unit as a main source of heat. which, as mentioned above, is an advantage not only to the consumer of electrical energy but also to the producer as daily consumption peaks of electrical energy are levelled out. The air heating and ventilation system accord¬ ing to the invention has been described above by way of example by means of one specific embodiment, and it is to be understood that the structure of the system may differ from the specific structure shown in the drawing without, however, deviating from the scope of protection defined in the attached claims. The basic idea of the invention is that the required basic heat is produced by the heat storing unit while the tem¬ perature adjustment is carried out by means of the duct heaters controlled separately for each room space. The duct heaters may be of any known structure though electrically heated units offer the simplest and most easily controllable alternative.

Claims

Claims :

1. An air heating and ventilation system, com¬ prising a supply air duct (1); an exhaust air duct (2); a heat recovery unit (LTO) between the supply and exhaust air ducts (1, 2) for transferring heat from the exhaust air into the supply air; a heat storing unit (MV) for storing heat and for delivering it into the air passed therethrough; and a damper (SP) in the supply air duct (1) for passing air partly directly and partly through the heat storing unit (MV) into room spaces (3, 4, 5, 6) to be heated, c h a r a c¬ t e r i z e d in that the damper (SP) is controlled in such a manner that the heat storing unit (MV) supplies the heating system with basic heat while ad¬ justment heat is supplied separately for each room space by duct heating units (KL4, KL5, KL6) provided in a supply air distribution duct (7) and controlled by thermostats (TE4, TE5, TE6) provided for each room space, respectively.

2. A system according to claim 1, c h a r a c¬ t e r i z e d in that the damper (SP) is controlled by means of a thermostat (TE3) disposed in a suitable room space (3) to be heated.

3. A system according to claim 1, c h r a c¬ t e r i z e d in that the temperature of the heat storing material contained in the heat storing unit (MV) is controllable by means of a thermostat (TE1) sensing the outdoor temperature.