ÖNORM EN 835

Heat cost allocators in accordance with11115 standard are instruments for the registration of the heat output of radiators in consumer units. Consumer units are dwellings, office buildings, business premises or industrial plants in which the heat is supplied by a common central heating system or by a common district heating connection. A complete grouping of consumer units is called an account unit. It could be necessary to divide an account unit into user groups, if an account unit comprises consumer units with typical differences (e.g. technically different types of heating systems or different by way of consumption e.g. industrial plants as opposed to private apartments). Heat cost allocators only allow the determination of the heat consumption of each radiator in a consumer unit as a share of the total heat consumption of the account unit or user group (see clause 3). It is therefore necessary to determine this total heat consumption either by measuring the consumed fuel quantity or the amount of heat delivered (the latter e.g. by a heat meter). The condition for correct use of heat cost allocators in accordance with this standard is that they are used in a heating system which - at the time of installation of the heat cost allocators, corresponds to the state of the art and - is operated in accordance with the state of the art (see annex A, A.1). Heat cost allocators in accordance with this standard shall not be used for heating systems where the temperature limits are exceeded, where the rating factor for the thermal power, Ka, is not clearly specified or where the heating surface is inaccessible. This applies e. g. to following heating systems: underfloor heating radiant ceiling heating flap-controlled radiators radiators with ventilators