Hourly and daily average values of coolant should be determined on the basis of the readings, which record carrier options. Based on 2, metering units of heat and coolant equipped with measuring means, registered in the State register of measuring and obtaining a positive expert opinion of the Ministry of Energy of the Russian Federation Gosenergonadzor. According to 2, heat meters should be provided to measure the thermal energy of hot water with a relative error of no more than: * 5%, the temperature difference between supply and return piping from 10 to 200C * 4%, the temperature difference between feed and return are more than 200C. Heat meters shall be provided to measure the thermal energy of steam with a relative error not exceeding * 5% in the range of steam flow from 10 to 30% * 4% in the range of steam flow from 30 to 100%. Counters should be provided to measure the mass (volume of fluid) with a relative error of no more than * 2% in the range of water and condensate from 4 to 100%. Counters couple must provide a mass measurement of coolant relative error of no more than: * 3% in the range of steam flow from 10 to 100%. Metering devices that register the pressure of coolant, should be provided to measure pressure with a relative error of less than 2%. Metering devices, recording time should be provided to measure the current time with a relative error not exceeding 0.1%. Criteria for selection of heat meters.