Heat Cost Allocators (Radiator HCA)

A heat cost allocator is an electronic device mounted on each radiator in centrally heated buildings that records that radiator’s share of the heat emitted in the building. Consumption is not recorded in kWh but as a unitless value that can be compared with the other radiators in the same building; heating costs are allocated according to these shares. Heat cost allocators are used in buildings where the radiators are supplied from different vertical risers and there is no single metering point at the apartment entrance. In systems with a manifold for each apartment, consumption is measured directly with a heat meter. This category features the Qundis Q caloric 5.5 radiator heat cost allocator; thanks to wireless (wM-Bus) reading, it can be read without entering the apartment. Our guide How to Read a Heat Cost Allocator explains how to read the values on the display and how they are reflected in the bill.

How Does a Heat Cost Allocator Work?

The device is fixed with a mounting kit at the mounting point on the radiator determined according to EN 834. Its sensors measure the surface temperature of the radiator and, in two-sensor mode, also the room temperature; a consumption value is accumulated from the temperature difference and the time. The Qundis Q caloric 5.5 can be programmed for single-sensor operation (the room temperature is assumed to be constant) or for two-sensor operation.

Radiator Rating Factors and Evaluation Logic

A large panel radiator and a small radiator at the same temperature do not emit the same amount of heat. For this reason, each device is matched with rating factors that represent the thermal output of the radiator it is mounted on (KQ) and the thermal coupling between the sensor and the radiator (KC). If the factors are programmed into the device (product scale), the displayed values can be compared directly; with the standard (uniform) scale, the units read are multiplied by the factors in the cost calculation. This is why the type and dimensions of each radiator are recorded during installation; if radiator data is missing, the allocation will be incorrect.

When Is a Heat Cost Allocator Used Instead of a Heat Meter?

A heat meter can be installed in manifold-based systems where each apartment is supplied from a single flow–return line. In buildings where the radiators are supplied from different vertical risers, there is no single point at which one meter per apartment could be installed; in this case, a heat cost allocator is mounted on each radiator. Where heat cost allocators are used, they are generally fitted to every radiator in the apartment; check your local regulations for the specific heat cost allocation requirements.

According to the manufacturer, the Q caloric 5.5 can be used on sectional (finned), tubular and panel radiators, radiators with an internal tube register, and convectors. It is not used with steam heating, underfloor heating, radiant ceiling heating or radiators with flaps.

Reading: Wireless (wM-Bus), Without Entering the Apartment

The Q caloric 5.5 transmits radio telegrams in the 868 MHz band in accordance with EN 13757-4 (wireless M-Bus). The P2 type offered on our site works with the manufacturer’s walk-by reading (Q walk-by) and fixed-receiver automatic reading (Q AMR) systems; since it also broadcasts OMS (Open Metering System) compliant telegrams in C-mode, it can be read with OMS-enabled receivers. For our meter reading and cost allocation service in Türkiye, see our Remote Meter Reading and Billing page.

Battery and Mounting Options

The manufacturer’s data sheet specifies a battery life of 10 years of operation plus a 1-year reserve. In addition to compact mounting, the P2 and P3 types are available with a remote sensor on a 1.5 m, 2.5 m or 5 m cable.

What Affects the Price of a Heat Cost Allocator?

• Number of radiators: each radiator needs one device, so the cost is per radiator, not per apartment.
• Mounting material: a mounting kit suited to the radiator type and, if required, a remote sensor.
• Reading infrastructure: walk-by reading or permanent receivers installed in the building.
• Scope of service: installation, determination of the radiator rating factors, periodic reading and the cost allocation calculation.

The current price is shown on the product page; contact us for a quote for your building.

Heat Cost Allocator vs. Heat Meter

For a detailed comparison of the two methods, see our article Heat Meter or Heat Cost Allocator?; for the allocation calculation, see our guide How Are Central Heating Costs Allocated? In Türkiye, Novus Energy also provides meter reading and heat cost allocation services for buildings with heat cost allocators.

Frequently Asked Questions

What does a heat cost allocator measure?

Based on temperature measurement, it records the heat emitted by the radiator it is mounted on as a unitless consumption value. This value is not in kWh; it determines the cost share by comparison with the other heat cost allocators in the same building.

Does every radiator need a heat cost allocator?

As a rule, yes. Where heat cost allocators are used in an apartment, a device is fitted to every radiator, and the apartment’s consumption is determined by reading all of its devices. Check your local regulations for the specific requirements.

How is a heat cost allocator read?

The current consumption and the value stored on the annual billing date appear in turn on the device display. Since the Q caloric 5.5 also transmits these values by radio, it can be read without entering the apartment, either by walk-by reading or with receivers installed in the building.

How long does a heat cost allocator battery last?

Qundis specifies a battery life of 10 years of operation plus a 1-year reserve for the Q caloric 5.5.

Can heat cost allocators of different brands be used in the same building?

This is not recommended. Qundis states that the Q caloric 5.5 cannot be used together with devices from other manufacturers in the same building; the measuring system and calculation method must be the same throughout the building.