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After a brief description of the advantages of district heating, the necessity for district heat measurement is outlined and the suitability of the existing heat meters examined. A system is described where the flow-rate and temperature difference of every data point is measured by, means of corresponding transducers and-their signals transmitted on a highway to the central processor, under its own command, for computing, It also performs additional functions, such as, address sequence generation, preparation of bill, etc. The minimum number of houses and their density for an economically viable system is given. A:parallel transmission is suggested for, address signals and serial for data signals. The cable requirement with its layout is calculated. The sampling timings' and quantization intervals for transducer signals are considered and scanning timing for the system is given. The reason for choice of a thermal flowmeter as a part of the heat transducer is discussed. (Comments on other flow-meters are presented in the Appendices). After an introduction to the past work on thermal flowmeters, the interaction between heat flow and fluid flow is described in' terms of. heat transfer coefficient. The dependence of heat transfer coefficient on temperature is exemplified. Two layouts of the thermal flow transducer: the flow sensor (i) under-the heater, and (ii) at the downstream side of the heater, are considered and experiments done with both types of transducers are described. The. following dimensionless relations between the change in heat injection rate and the change in heat transfer coefficient for closed- and open-loop operation of the:flow-meter are derived, respectively: [equation removed] These equations take into account the thermal conductance invariably present between the flow sensor and the flow tube wall, but neglects the lateral thermal conductance of the flow tube. Further, it is shown that for closed-loop operation, the thermal flowmeter output is given by [equation removed] The experimental results have been compared with those derived from these equations. It is pointed out that the quantities [formula removed] and [formula removed] of a thermal transducer may be considered as its parameters. The thermal flowmeter has been operated in the pulse heat injection mode, (this has been Suggested in the literature, but not done in practice). Combined d.c. and pulse heat injection is suggested and it is shown that in such a case Δq ∝ f (3.45). This form of heat injection is successfully applied to improve the flowmeter output and its resolution. The electronic circuits, used for operation of the flow-meter are described. Experiments have been performed with four forms of transducer and found that the transducer with the flow sensor at the side of the heater and operating with the combined d.c and pulse heat injection into the boundary layer gives most Suitable output. The flowrate and temperature difference transducers are mounted together to form the heat transducer. The test of this transducer has been done employing a heat generator unit. The temperature difference meter output is linear, but the flowmeter output' is nonlinear. However, linearization is only required when the heat transducer is to be used for some purpose other than the present one. Finally, experiments are described of induced transients tests in a cable in order to get some idea of signal interaction between the address and data signals.