The present invention relates to a method and a heat con¬ sumption meter for recording the amount of heat consumed from radiators, comprising a housing with a calculator unit and with temperature sensors connected thereto for radiator and room temperatures, wherein the calculator unit is intended for calculating the heat emission from the radiator on the basis of the measured temperatures.

Heat consumption meters for radiators are used m par¬ ticular for central and district: heatmσ installations for the distribution of the total heat costs m propor¬ tion with the heat consumption. The neat emission of a radiator is proportionate with the effective neatmg sur¬ face multiplied by a function of the difference between the temperatures of the radiator and the ambient air. Thus, in reality the meter serves to integrate this func¬ tion over time, and numbers of different types of heat consumption meters are known of which some do not take into account the temperature of the ambient air, but base the measurement entirely on the temperature of the radia¬ tor, such as evaporation measuring devices, wnile other well-known types measure both said temperatures by means of thermoelements, and wherein the thermocurrent produced is measured by means of an Ah-meter which may consist of e.g. an irreversible electrolyte meter that discharges mercury in an amount that corresponds to the heat emis¬ sion of the radiator.

Although radiators with dual-sensor meters for measuring the radiator as well as the room temperature provide a comparatively accurate measurement of the heat consump¬ tion, the known αesigns of such meters, however, are as- sociated with a number of drawbacks, such as various pos¬ sibilities for cneatmg the heat consumption meter, e.g.

by covering, heating or cooling of the temperature sen¬ sors, and limitations as to the accuracy of the marginal ranges for the occurring temperatures or in atypical op¬ eration conditions. Thus, in order to avoid recording of an "idle" consumption without the radiator emitting heat, the meter may be provided with such functional limitation that the meter does not record any consumption until the radiator is above a certain minimum temperature. If, how¬ ever, it is set too high it may mean that heat emission from the radiator which should have been measured is not measured. It may also occur that the meter measures a heat emission from the radiator which is actually taking place but cannot be measured since the heat emitted is not to be part of the neatmg costs to be distributed since the radiator has been heated in some other way than through the supply pipes, in particular in very hot sum¬ mers and/or by direct incident sunlight on the radiator or by simultaneous use of another heat source.

It is the object of the present invention to provide a method and a heat consumption meter for a radiator for recording the heat consumed a radiator which provides the option of a more accurate measurement relative to the actual heat consumption compared to the existing meters.

This is obtained by the method according to claim 1 and by use of the meter according to claim 9. Hereby it is namely obtained that an amount of heat which is emitted from the radiator to the room when the radiator is turned off is not recorded as heat consumption if a high room temperature has arisen within a 24-hour cycle, in par¬ ticular due to heating by sun or other heat source, com¬ pensation being made by the calculated negative heat con¬ sumption during the hottest part of said 24-hour cycle.

Hereby it is prevented that the heat consumption meter records a non-actual heat consumption during the summer when the heating installation is otherwise shut down.

Preferred embodiments of the invention utilises said mode (mode 3) only when the numerical difference between the calculated room temperature and the calculated radiator temperature is below a pre-determined limit value. Hereby it is ensured that the meter cannot be manipulated to calculate a very large negative heat consumption.

According to a further preferred embodiment of the inven¬ tion, the meter has an alternative heat recording mode (mode 1, 2) in which no recording of negative consumption is carried out when said difference in temperature is above the predetermined limit value, and wherein calcula¬ tion of the heat consumption is carried out by measure¬ ment of a predetermined substitute room temperature in¬ stead of the calculated room temperature.

The invention will now be described in further detail with reference to the drawings wherein

Figure 1 illustrates an embodiment of a heat consumption meter according to the invention, seen from the front,

Figure 2 is a vertical sectional view along the line II- II in Figure 1 of the same,

Figure 3 is a perspective view of a print card the me¬ ter shown Figures 1 and 2,

Figure 4 is a first embodiment of a fitting for a heat consumption meter seen from the front,

Figure 5 is an end view of the embodiment shown Figure 4,

Figure 6 is a front view of an alternative embodiment of a fitting,

Figure 7 is an end view of the embodiment shown in Figure

6 seen from the end,

Figure 8 is a diagram for illustrating the calculation of the heat consumption in various temperature conditions, and

Figure 9 is a flow chart for the meter's calculation of the heat consumption.

The electrical heat consumption meter shown Figures 1 and 2 has a housing 1 of a thermoand electrically insu¬ lating material, preferably plastics, consisting of a bottom portion 2 and an upper and a lower cover 3 and 4, respectively. Through a window in the uppermost cover 3 an LCD display 5 can be seen as will appear from Figure 1. The uppermost cover 3 is secured to the meter by means of a lead seal 6 which is to be destroyed in order to al- low access to the housing 1 interior. The uppermost lid secures the lowermost lid 4 in a manner not specifically illustrated which means that it cannot be removed either without breaking the lead seal 6.

Said display 5 is mounted on a bilaterally circuit board

7 secured the housing. On the side opposite the dis¬ play a calculator unit is mounted in the form of a micro¬ processor 8, and the same side of the board 7 also car¬ ries a radiator temperature sensor 9 and three rear ele- ment indication switches 17, only one of which being visible in Figure 2. On the front of the circuit board 7

a room temperature sensor 10 is also provided, a multiple plug 11 which allows for power supply from an external power source and for RF-communication with programming and data input and output readers via wire connections. Input and output reading may moreover be carried out over an optical infrared communication interface 15 with di¬ odes 15A through windows 16 in the uppermost cover 3. As a third not shown option the data input and output read¬ ing may be effected via a radio transmitter/receiver which is in that case arranged in the housing 1 and con¬ nected to the electrical circuit via the multiple plug 11.

In Figure 2, below the lowermost cover 4 a battery pack- age 12 is shown for supplying power to the meter via bat¬ tery clamps 13.

The heat consumption meter described in the aforegoing is intended for mounting on a radiator over a fitting 14 shown in Figure 12 which is preferably mounted on a not shown mounting pin secured to the radiator and extending through an opening 18 in the fitting and also through an opening 19 in the bottom portion 2 of the meter. In Fig¬ ure 2 the fitting 14 is also shown to have an indentation 20 in which the heat consumption meter 9 for a radiator is arranged when the meter is mounted on the fitting. The sensor 9 is, like the room sensor 35, preferably NTC- resistances, the resistance values of which are a measure of the temperatures that they are to read and the tem- perature of the fitting 14 and the temperature of the room, respectively. The values determined by the tempera¬ ture sensors are not the correct ones but they are calcu¬ lated by the electrical circuits 7,8 on the basis of con¬ stants determined in advance in climate rooms for the in- dividual radiator and fitting types.

Since large numbers of radiator types are available with many different designs it is necessary to use many dif¬ ferent types of fittings to obtain good and unambiguous transmission of heat from the radiator to the meter, which types of fittings are adapted to the relevant ra¬ diator constructions. Two different fitting designs are shown in Figures 4-7. The fitting 21 shown Figures 4 and 5 is intended for attachment on a plane radiator sur¬ face with its planar side while the opposite side is pro- filed with a number of grooves 22 and guides 23. Depend¬ ing on the location of the grooves, the fitting indicator switches 17 will be actuated by guides 23 when the meter is mounted in the fitting. By using three switches 17 different widths and locations of the grooves 22 may ac- tuate one, two or three of the switches 17 which means that a total of seven combinations for actuation is pos¬ sible, the eighth combination, in which neither of the switches is actuated, indicating that the meter is not mounted on a fitting. The various combination types are designated e.g. A,B,C , and the combination of actuated switches 17 will indicate the type of fitting which is caused to be displayed on the display 5 by means of the electrical circuit. Thus an unequivocal reading and dis¬ play of the fitting type is thus produced whereby it may readily be verified that the correct fitting A, B, C has been used in connection with the relevant radiator.

Figures 6 and 7 illustrate a second fitting 24 for mount¬ ing on another radiator type, and here the grooves 25 and the guides 26 have another width and location than on the fitting 21 in Figures 4 and 5. In the fitting 24, in ad¬ dition to the mounting opening 18, the indentation 20 for receiving the heat consumption sensor 9 is shown. 30 the fitting is made of a good heat-conductor, preferably alu- minium, and they have a comparatively short length which advantageously constitutes one third of the length of the

house in order to avoid that too much heat is transmitted to a mounted meter whereby it is ensured that the latter and thus also the room sensor 10 is not unduly heated. The fittings are advantageously symmetrical about a cen- tral axis thereby ensuring that they are not inverted during mounting.

If the number of switch actuation combinations is insuf¬ ficient, more grooves and guides on the fittings and fur- ther switches 17 on the meter may be provided, or switches 17 may be used which have several switch posi¬ tions m connection with guides and grooves of differing depths .

Reference is now made to Figure 8 that diagrammatically illustrates various temperature conditions that determine the way which the recording of heat consumption is to be calculated and recorded. In the diagram the horizontal ax s indicates the radiator temperature THB calculated by the electrical circuit determined on the basis of the value measured by the radiator temperature sensor 9. In a corresponding manner the vertical axis designates the room temperature TRB calculated by the circuit on the ba¬ sis of the value measured by the room temperature sensor 10. In the diagram, the various temperature modes are designated mode 0, mode 1, mode 2, and mode 3. In mode 0 that covers the temperature range which the calculated radiator temperature is below a marginal value ^THB,J , no recording is made of heat consumption since it is here assumed that no heat is emitted from the radiator. This radiator surface starting temperature ^{T B} may e.g. be set to 15°C. In this operation mode, there is only a poor possibility of falsifying the measurement result, e.g. by cooling of the radiator around the fitting or by mten- sive heating of the meter from its front whereby the room sensor measures a temperature which is too elevated.

Should this occur over a protracted period during the heating season, the calculator unit of the meter is ar¬ ranged for using a set temperature TRBE, the so-called substitute room temperature, which may e.g. be set to be 20°C, instead of the calculated room temperature TRB. However, such intensive heating of the meter through some time will also cause the radiator temperature sensor to be heated whereby the calculating unit will pass from mode 0 to one of the other modes by transgression of said border value THBG.

In the normal operation mode during the heating season the calculated radiator and room temperatures are com¬ prised within the range defined in the diagram as mode 1, and the energy consumption is calculated in accordance with the formula E = K ⁺ (THB - TRB) ¹ '", wherein K is a pre-set characteristic value for the relevant radiator type and size, and wherein the potency 1,33 is a commonly known normal value which may, particular cases, have a slightly different value. The mode-1 range has an upper limit as regards the calculated room temperature of a border value TRBG above which the calculated room tem¬ perature TRB is not used in the heat consumption, but the above-defined substitute room temperature TRBE. Like mode 0, the mode-1 state, provides only a poor possibil¬ ity of falsifying the measurement result. Thus, although the room temperature sensor could be heated a few degrees whereby the calculated room temperature TRB becomes too low, the result would very easily be that the temperature conditions leave mode 1 to transgress the said limit TRBG and enter mode 2. The other, but very unlikely risk of cheating would be to cool the radiator temperature sen¬ sor.

In the mode-2 area which is, in the diagram, above the mode-1 area, the heat consumption is calculated accor-

dance with the formula E = K* (THB - TRBE) ¹ '" which cor¬ responds to the expression defined above, the only dif ^¬ ference being that instead of the calculated room tem¬ perature TRB the said substitute room temperature TRBE is used. The mode-2 state is characterised in that the ra¬ diator is turned on while a very high calculated room temperature TRB is recorded. This may be due to e.g. the radiator being covered or incident sun, or there may be particular reasons for a high room temperature. Covering of the radiator and incident sun will cause the measured room temperature to be too high, and the measured radia¬ tor temperature will also be too high. The calculated heat consumption will be too low if the formula for mode 1 is used for the calculation. It is not possible to dis- tmguish between covering and incident sun since the tem¬ perature curves for these two situations are very much alike, but incident sun will often occur at small inter¬ vals and only case of meters which have been mounted opposite a window. Incident sun may also mean that the thermostatic valve of the radiator turns off the water flow. When the substitute room temperature is used for calculating the heat consumption, possible inconvenient side effects from undesired manipulation are avoided.

In the inclined area in the diagram m Figure 8 desig¬ nated mode 3, the dotted centre line indicates the mode which the calculated room temperature is identical with the calculated radiator temperature. The mode-3 area is delimited by lines that are parallel with said centre line and which are situated at a distance TBG therefrom, wherein TBG may be e.g. 5° above and below the centre line, i.e. the calculated room temperature may vary 5° to either side of the radiator temperature.

It is a precondition for mode 3 that the radiator is turned off or at least that no heat is supplied to or re-

moved from the radiator through the conduits leading thereto. In this context, the precondition for the calcu¬ lator unit entering mode 3 is that the calculated room temperature increases above the calculated radiator tem- perature. The heat consumption will also in mode the 3 be calculated in accordance with the formula given for mode 1, but here the consumption is calculated with signs and summed m a separate mode-3 register. If the room tem¬ perature is thus higher than the radiator temperature the heat received by the radiator from the surroundings is calculated as a negative heat consumption.

When the room temperature subsequently drops below the radiator temperature thereby causing the radiator to emit heat to the surroundings, a positive heat consumption is calculated. When the meter leaves mode 3 the contents of the separate mode-3 register is added to the total con¬ sumption and the register is re-set to zero. The mode-3 state may e.g. occur during a hot period of the year where the room temperature at daytime may exceed the ra¬ diator temperature but drops there below at night. Thus, the mode-3 state prevents that the positive "heat con¬ sumption" during the night is recorded as an actual con¬ sumption, but that event compensation is made therefor by a negative heat consumption during the day. The con¬ sumption the mode-3 register which is very often zero is added to the total consumption once during 24 hours, optionally following multiples of 24 hours, in order to avoid a sudden large leap the counts. It should be noted that it is important that a cycle of 24 hours or a multiple of 24 hours is used, whereby it is periodically estimated whether there is constantly a negative counting which could be indicative of cheating. This could be ob¬ tained with very good insulation of the meter, but practice this would probably be associated with much trouble. The temperature state which is above the mode-3

area is designated mode 2 m the diagram like the area beiow the mode-3 area. The heat consumption is calculated in accordance with the same formula as mentioned above in connection with the other mode-3 area, and it is charac- teristic of this upper mode-2 area that the calculated room temperature is considerably above the calculated ra ^¬ diator temperature.

In practice, this state would hardly occur unless as a consequence of unintentional manipulation, such as inten¬ sive heating of the meter from its front. Thus, in the calculation of the heat consumption said substitute room temperature is used to prevent undue recording of a negative consumption. If a negative consumption is con- tinuously measured mode 3, switching is made to mode 2.

The flow chart included Figure 9 shows the heat me¬ ter's determination of the actual mode by calculation of the heat consumption correspondence with the calcula¬ tion procedure described above in connection with Figure 8. The arrow 30 shown connection with Figure 8 indi¬ cates the sequence of the decisions in the flow chart, and the short bold lines 31,32 and 33 indicate the area limits at which questions are put in the flow chart of Figure 9. The meter may only enter mode 3 when the room temperature exceeds the radiator temperature (TRB>THB) . For this purpose flag 3, cf. Figure 3, is used which is applied when this condition has been complied with. If the meter enters other modes, the flag 3 is set back.

From the explanation given above connection with Fig¬ ure 8, it will appear that in case of naturally occurring temperature fluctuations, in particular when the weather is hot, an approximately correct recording of the heat consumption is obtained, since it is possible with the

meter to compensate for a positive, not actual consump¬ tion by a corresponding negative consumption. In abnormal operating conditions that usually occur due to the ma¬ nipulation in order to cheat the meter, measures have been taken to counter falsified recordings whereby, from an overall point of view, a meter is provided which would all operating conditions yield a satisfactory, ap¬ proximately correct recording of the heat consumption.

On the display 5 the meter the recorded heat consump¬ tion units and the consumption the previous year may ad¬ vantageously be shown in an information cycle, as well as an installation number and a scale size indicating the weighing factor used for the relevant radiator in the calculation of the heat consumption units.

The measured and calculated values of room temperature and radiator temperature as well as the fitting denomina¬ tions A,B,C will usually not be shown said information cycle, but may be brought on display by the operators when reading the meter during replacement of battery and the like.

Thus, this preferred embodiment of the invention provides an electric heat consumption meter for a radiator for re¬ cording heat consumed from a radiator comprising a hous¬ ing with a bottom portion and a cover with a calculator unit and temperature sensors connected therewith for ra¬ diator and room temperatures, and a power supply, wherein the calculator unit is arranged for calculating the heat emission from the radiator on the basis of the pre-set temperatures and an overall weighing factor, scale size, and wherein the room temperature sensor is arranged below the cover.

In this preferred embodiment for an electric heat con¬ sumption meter for a radiator, the bottom portion and cover of the housing are made of a non-conductive mate¬ rial, and the radiator temperature sensor is arranged ex- teriorly of the bottom portion of the housing and mounted good heat-contact with a well conducting fitting which is adapted to and secured onto the radiator, and which has, on its meter mounting surface, a number of protru¬ sions and/or indentations, the design and locations of which are characteristic of the relevant fitting, and wherein the meter has a number of switches that face to¬ wards the fitting and which may be actuated in correspon¬ dence with the protrusions/indentations of the fitting for reading the type of fitting with a well-conducting fitting adapted for and secured onto the radiator, and which has on its meter mounting surface a number of pro¬ trusions and/or indentations, the designs and locations of which are characteristic of the relevant fitting, and wherein the meter has a number of switches facing towards the fitting that may be actuated correspondence with the protrusions/indentations of the fitting for sensing the type of fitting.

Thus, by making the cover of the housing as well as its bottom portion of a non-conductive material, good shield¬ ing of the room temperature is provided which means that it is not unduly influenced by the radiator, and this ar¬ rangement known per se of the room temperature sensor m the meter housing it is simultaneously substantially pre- vented that manipulation of the meter, such as covering thereof, heating of the room temperature sensor or cool¬ ing of the radiator temperature sensor, will change the difference between the radiator and room temperatures and thus the recording of the consumption. It should be noted that the sensors, and particular the room temperature sensor, will not in normal conditions bring about the

correct radiator and room temperatures which are, how¬ ever, calculated by the calculator unit on the basis of predetermined characteristic values for the radiator and the meter. Owing to its configuration, the well conduct- mg fitting thus has an unambiguous and good contact with the radiator whereby the calculated radiator temperature will always be right. The protrusions/indentations pro¬ vided the fitting in connection with contact means on the back of the meter, which are selectively actuated by the fitting, serve to ensure that in connection with the relevant radiator that the correct fitting therefor is used which may, via said switches, be used for display on a display. This it is ensured to a high degree that the temperature measurement and thus the heat consumption re- cording are correct.

In one embodiment of the radiator meter according to the invention the conductive fitting is a separate element which is independent of the housing and whose length con- stitutes a maximum of one third of the length of the housing. Hereby the shielding of the room temperature sensor is further enhanced whereby this measurement is only to a very small degree influenced by direct heating from the radiator.

Said protrusions or indentations may have any of a number of shapes such as bosses and bores or may be through- going grooves with interjacent material guides in the me¬ ter mounting surface of the fitting. Since many different types and configurations of radiators are available, there is a need for several different fittings in order to obtain good, unambiguous transmission of heat via the fitting. For sensing the relevant type of fitting the protrusions/indentations of the fitting are, in accor- dance with an advantageous embodiment according to the invention, constituted of at least two grooves at each

side which are symmetrically arranged, and the meter has at least three switches which each has at least two switching functions. By means of these switches a number of combinations are available, depending on their actua- tion, for indicating the type of fitting, and case further combinations are required, each switch may in that case have a further switching function. The symmet¬ rical arrangement of the grooves the fitting prevents, of course, it from being inverted. The material guides situated between the grooves and with which the back of the meter is in contact transmit the radiator heat di¬ rectly to the meter housing and by suitable dimensioning of these material lists the heat supply to the meter may be balanced to prevent undue heat transmission in par- ticular to the room temperature sensor from occurring.

As stated above, the calculator unit comprises a micro¬ processor that calculates the actual values for radiator temperatures and room temperatures on the basis of the supplied measurement values for radiator temperature and room temperature by means of pre-determined characteris¬ tic figures of the relevant radiator in accordance with the invention. This is convenient since a more versatile heat consumption meter for a radiator is hereby obtained which may also be used in installations m combination with other meter types.

The microprocessor according to the invention may advan¬ tageously be connected to an optical sectional plane and a multiple plug for input and output of data for program¬ ming, etc. With an optical programming and input and out¬ put units or via a wiring to the multiple plug, the in¬ formation contained in the microprocessor may hereby readily be modified or read. Moreover, conveniently the meter also has an LDC-display in connection with the mi-

croprocessor which allows that information may always be read, even in case of a low current consumption.

It is a further option that the input and output of data, etc., may always be effected via a radio transmit¬ ter/receiver integral with the meter and connected to the microprocessor. When the meter is provided with such ra¬ dio transmitter/receiver it will be "inspected" only at infrequent intervals of e.g. 8-10 years and therefore the switches have the further essential function of causing the radio transmitter to immediately transmit a message in case the meter is dismounted from the radiator or in case manipulation thereof is carried out in any other way.