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The relevant requirements of Annex I, the specific requirements and the conformity assessment procedures listed in this Annex, apply to thermal energy meters defined below, intended for residential, commercial and light industrial use.
A thermal energy meter is an instrument designed to measure the thermal energy which, in a thermal energy exchange circuit, is given up by a liquid called the thermal energy-conveying liquid.
A thermal energy meter is either a complete instrument or a combined instrument consisting of the sub-assemblies, flow sensor, temperature sensor pair, and calculator, as defined in Article 4(2), or a combination thereof
θ | = | the temperature of the thermal energy-conveying liquid; |
θin | = | the value of θ at the inlet of the thermal energy exchange circuit; |
θοut | = | the value of θ at the outlet of the thermal energy exchange circuit; |
Δθ | = | the temperature difference θin — θοut with Δθ ≥ 0; |
θmax | = | the upper limit of θ for the thermal energy meter to function correctly within the MPEs; |
θmin | = | the lower limit of θ for the thermal energy meter to function correctly within the MPEs; |
Δθmax | = | the upper limit of Δθ for the thermal energy meter to function correctly within the MPEs; |
Δθmin | = | the lower limit of Δθ for the thermal energy meter to function correctly within the MPEs; |
q | = | the flow rate of the thermal energy conveying liquid; |
qs | = | the highest value of q that is permitted for short periods of time for the thermal energy meter to function correctly; |
qp | = | the highest value of q that is permitted permanently for the thermal energy meter to function correctly; |
qi | = | the lowest value of q that is permitted for the thermal energy meter to function correctly; |
P | = | the thermal power of the thermal energy exchange; |
Ps | = | the upper limit of P that is permitted for the thermal energy meter to function correctly. |
The values of the rated operating conditions shall be specified by the manufacturer as follows:
For the temperature of the liquid: θmax, θmin,
for the temperature differences: Δθmax, Δθmin,
subject to the following restrictions: ; Δθmin = 3 K or 5 K or 10 K.
For the pressure of the liquid: The maximum positive internal pressure that the thermal energy meter can withstand permanently at the upper limit of the temperature.
For the flow rates of the liquid: qs, qp, qi, where the values of qp and qi are subject to the following restriction: .
For the thermal power: Ps.
The following accuracy classes are defined for thermal energy meters: 1, 2, 3.
The maximum permissible relative errors applicable to a complete thermal energy meter, expressed in percent of the true value for each accuracy class, are:
For class 1: , with Ef, Et, Ec according to points 7.1 to 7.3.
For class 2: , with Ef, Et, Ec according to points 7.1 to 7.3.
For class 3: , with Ef, Et, Ec according to points 7.1 to 7.3.
The complete thermal energy meter shall not exploit the MPEs or systematically favour any party.
After an appropriate test, taking into account the period of time estimated by the manufacturer, has been performed, the following criteria shall be satisfied:
Flow sensors: The variation of the measurement result after the durability test, when compared with the initial measurement result, shall not exceed the critical change value.
Temperature sensors: The variation of the measurement result after the durability test, when compared with the initial measurement result, shall not exceed 0,1 °C.
Accuracy class
Limits of flow rate
Limits of temperature
Limits of temperature difference
Place of the flow sensor installation: flow or return
Indication of the direction of flow
The provisions for sub-assemblies may apply to sub-assemblies manufactured by the same or different manufacturers. Where a thermal energy meter consists of sub-assemblies, the essential requirements for the thermal energy meter apply to the sub-assemblies as relevant. In addition, the following apply:
where the error Ef relates the indicated value to the true value of the relationship between flow sensor output signal and the mass or the volume.
where the error Et relates the indicated value to the true value of the relationship between temperature sensor pair output and temperature difference.
where the error Ec relates the value of the thermal energy indicated to the true value of the thermal energy.
Flow sensor: | Accuracy class |
Limits of flow rate | |
Limits of temperature | |
Nominal meter factor (e.g. litres/pulse) or corresponding output signal | |
Indication of the direction of flow | |
Temperature sensor pair: | [X1Type identification (e.g. Pt100)] |
Limits of temperature | |
Limits of temperature difference | |
Calculator: | Type of temperature sensors
|
Editorial Information
X1 Substituted by Corrigendum to Directive 2014/32/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of measuring instruments (Official Journal of the European Union L 96 of 29 March 2014).
Where a Member State imposes measurement of residential use, it shall allow such measurement to be performed by means of any Class 3 meter.
Where a Member State imposes measurement of commercial and/or light industrial use, it is authorised to require any Class 2 meter.
As regards the requirements under points 1.1 to 1.4, Member States shall ensure that the properties be determined by the utility or the person legally designated for installing the meter, so that the meter is appropriate for the accurate measurement of consumption that is foreseen or foreseeable.
The conformity assessment procedures referred to in Article 17 that the manufacturer can choose between are:
B + F or B + D or H1.