BS/EN 834-2013 pdf download.Heat cost allocators for the determination of the consumption of room heating radiators Appliances with electrical energy supply.
4 Functional principle and measurement methods
Heat cost allocators in accordance with this standard are measuring devices for the registration of the temperature integral with respect to time. The temperature is the basis for the determination of the heat emission of the room heating surfaces on which the heat cost allocators or their sensors are installed. Heat cost allocators with electrical supply as covered by this standard (in the following referred to as heat cost allocators) depending on the measurement method register all or only a part of the characteristic temperatures relevant for the heat emission of the room heating surface. The non-rated displayed reading value is the approximate value of the time integral of the measured characteristic temperature of the room heating surface or the time integral of the temperature difference between the room heating surface and the room.
The rated displayed reading value referred to as the consumption value (see 3.24) is obtained (see 5.3) from the non-rated displayed reading value (see 3.23) by multiplication by rating factors, particularly by those for the reference thermal output of the room heating surface (K0, see 3.37) and for the thermal contact between the sensors and the temperatures to be registered (Kr, see 3.38).
The consumption value is an approximate value for the heat emitted by the heating surface during the measurement period and the heat consumed by the user. The consumption value is either read off directly at the heat cost allocator or determined later by converting the non-rated displayed reading value.
The consumption value thus Is a measuring result containing properties of the measuring device, room heating surface, other boundary conditions and, in addition, uncertainties of the rating factors and the installation. Measuring deviations (measuring errors) of the registered heat therefore do not depend on the measuring device only. This means that heat cost allocators cannot be calibrated in the same manner as heat meters.
Due to the properties described, the measuring result will not be allocated any physical energy units. The consumption value is non-dimensional. It is used only as a relative value relating to the sum of the consumption values of the account unit or group of users. A relative value of a measured consumption value determined in this manner can be interpreted as a share of the heat consumption of the account unit or user group. This quantity is determined after the measurement period has ended for each individual radiator. From the sum of the consumption values for the radiators of a consumer unit, the described relative value can be determined as the share of the heat consumption of the relevant consumption unit in the total consumption of the account unit or user group.
Heat cost allocators usually consist of a casing, measuring sensors, a calculator unit, a display device, the energy supply, fixing elements and the seal. The seal serves to protect the heat cost allocator against unauthorized manipulation. The components of the heat cost allocator are manufactured in compliance with certain tolerances. Thus, each individual one of a particular kind of heat cost allocator (type, make) functions the same when used in an identical way.
Each heat cost allocator in accordance with this standard is a functional unit. It fulfils its intended task only as a whole, with all its components and properties acting in systematic cooperation and together with all other heat cost allocators within the same account unit or group of users. Tests of heat cost allocators in accordance with this standard are therefore always system tests, the results of which are only valid for the tested heat cost allocat,on system as a whole.
Heat cost allocators in accordance with this standard work according to one of the following measurement methods.
The single-sensor measurement method utihzes one temperature sensor. The sensor registers the temperature of the room heating surface or heating medium. Appliances with room temperature start sensors fall under the single-sensor measurement method.
The two-sensor measurement method utilizes two temperature sensors. One sensor registers the temperature of the room heating surface or heating medium, the second sensor registers the room temperature or a temperature in a defined relation to it.
Multiple-sensor measurement methods register a measure of the mean heating medium temperature using at least two radiator sensors and the room temperature using one other sensor. The measured values are used for determining the heating medium excess temperature applying a suitable algorithm.
5 General specifications
5.1 Base condition
The following applies for the base condition of the radiator:
— upper flow inlet;
mean heating medium temperature m = 40 °C to 60 °C;BS/EN 834-2013 pdf download.