Using accelerated durability tests to investigate the long-term properties of district heating meters

Project programme: Phase 1. Introduction activities. Phase 2. Principles of how to acquire relevant meter data. Phase 3. Supplementary acquisition of know-how. Phase 4. Data acquistion and processing. Phase 5. Test concept draft. Phase 6. Evaluation and adjustment. Phase 7 Final report. Status: To ensure fair consumer heat metering and billing, a district heating plant must obtain and install meters that measurement correctly - also during the fluctuating conditions that occur in practice. For meter manufacturers/suppliers, it is also important that their meters fulfill these functional requirements in practice. Heat meters are in practice often exposed to considerable fluctuations in flow and temperature differences - long-term and short-term, i.e. a short term influence could be the use of an instantaneous heat exchanger for producing domestic hot water combined with the start-stop function of a modern single-handle tap or mixing valve. The meters are also exposed to influences from pipe-bends and elbows, varying water quality etc. Although dynamic operational conditions are common in consumer installations, current type test do not include requirements for testing or dicumenting the meters' response to dynamic operation, and other long-term influences are only included to a limited extent. Various initiatives are underway within this field, among other things via CEN/TC 176. The OIML R72 standard on hot water meters covers vane meters specifying a procedure for durability testing. But there is no procedure for accelerated durability testing of all types of heat meters e.g. vane meters, ultrasound, magnetic inductive, fluidistor etc. Use of results: The results of the project, additionally supplemented with results of a current nordic project (a Nordtest project' Accellerated durability testing of flow meters') will be able to be used to influence the ongoing international work, e.g. CEN/TC 176 Heat Meters