What is BS EN 835 – Determining consumption of room heating radiators about? 
Heat cost allocators are used to acquire consumption charges in a decentralized manner. They're mostly employed when it comes to allocating heat charges to distinct consumers based on their particular heat use.
BS EN 835 is a European Standard discusses heat cost allocators for appliances without an electrical energy supply. The main aim of BS EN 835 is to provide best industry practices to ensure heat cost allocators play a positive role in maintaining energy efficiency of central heating systems.
BS EN 835 provides definitions, requirements and test procedures for heat cost allocators without electrical power supply.
Heat cost allocators in accordance with BS EN 835 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. 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. It is therefore necessary to determine this total heat consumption either by measuring the consumed fuel quantity or the amount of heat delivered.
Note: Heat cost allocators in accordance with BS EN 835 shall not be used for heating systems where the temperature limits are exceeded, where the rating factor for the thermal power, KQ, 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
- Fan-assisted air heaters
- Bath-tub convectors
- Heating systems where the radiators attached thereto are operated by steam
- Horizontal single pipe heating systems exceeding more than one consumer unit
Who is BS EN 835 - Determining consumption of room heating radiators for?  
BS EN 835 on determining consumption of room heating radiators  is relevant to: 
- Manufacturers of heat cost allocators
- Manufacturers of central heating systems
- Manufacturers of room heating radiators
- Quality control and testing personnel
- Engineers
- Local bodies
- Regulatory authorities
Why should you use BS EN 835 - Determining consumption of room heating radiators?  
Heat cost allocators are small low-cost devices which are fixed to all radiators in the property. The data heat cost allocators collect and remotely transfer to the billing system allows the operator to allocate the cost of the heating system to where it is being consumed. Hence consumption-based billing can be provided.
In this regard, BS EN 835 defines heat cost allocators without electrical power supply, based on the evaporation principle, which serve to establish the consumption value of a room radiator. It also specifies the minimum requirements for construction, materials, production, installation, function and evaluation of the displayed readings established by these measuring devices.
BS EN 835 specifies test procedures to establish the compliance with the stated requirements and gives instruction for the manner and the extent of their realization.
Thus, BS EN 835 helps you in manufacturing, assessing and verifying the reliability of manufactured heat cost allocators to demonstrate whether they are fit for purpose and contribute to providing accurate and fair meter readings.
