This text explains how to individualize a central heating system by using heat cost allocators. This technique is discouraged since the author of this text has verified in her own installation that the disadvantages are much higher than the practically non-existent advantages.
1. Central Heating
“Central heating” is understood as the technique in which a common boiler heats the water in the heating system of all the residents of a house or block of flats. The hot water is distributed throughout the building, typically through several rising and falling water pipes that simultaneously run through all the floors of each block.
In this way the cost of heating is divided equally among all neighbors. The objective of individualizing the central heating is to allow the regulation of each radiator in the building in such a way that each neighbor pays exclusively for what their radiators consume. As we will see, this objective is not achieved, and also the system is totally counterproductive since practically all the neighbors tend to pay more for having their houses colder than with the previous system.
2. How to Individualize the Central Heating.
This section explains how to individualize a central heating system. After installation, each radiator will look like the following:
The following elements are installed in each radiator:
- Thermostatic valve + Thermostatic head: These are the elements that are observed in the water inlet of the radiator. They allow you to adjust the temperature of the room by regulating the flow of hot water that enters the radiator.
- Heat Cost Allocator: It is the device located in the middle of the radiator in the photo. It is the key item of the individualization system. The allocator measures the difference in temperatures between the outside and the radiator itself and estimates an energy consumption for said radiator.
There is a very important detail to take into account. Typically, there are not two pipes, one with incoming water and one with outgoing water, for each household. Instead, ascending and descending pipes are used, which are tubes that cross the building vertically. Thus, in each home there are two tubes per room, and therefore all the tubes are shared among all the neighbors. For this reason, the heat dissipated in each home cannot really be measured, and for this reason heat cost allocators are used, which do not measure, but rather estimate the consumption of each home.
3. Disadvantages of Individualizing Central Heating
Typically the most mentioned advantage of individualization is that each radiator can be adjusted according to the needs of each home. The reality is that it is not necessary to individualize the central heating system to have that advantage. This can be achieved with the traditional system by regulating the faucet of each radiator. Furthermore, the multiple disadvantages of individualization are as follows:
- Work: There is not always adequate space to put the thermostatic valves on each radiator. The original system was not designed for them. That can translate into the installation of valves with less benefits, and in botched jobs that each neighbor is forced to do at home. Bear in mind that the cost of this installation is paid by each neighbor and can be high.
- Cost of materials: Apart from the previous works, you have to take into account the cost of each visit of the individualization provider (46€ plus VAT in my case), the cost of each heat cost allocator (27€ plus VAT) and the cost of each valve plus the thermostatic head (30€ minimum). In a home with 7 radiators we are talking about almost 500€ plus the price of the work if it were necessary to adapt a pipe for the installation of the valves.
- Renewal of heat cost allocators: Every time a cost allocator breaks or the battery runs out (typical if there are children at home who can press the reading button regularly), it is necessary to pay again the 46€ + VAT of the visit of the installer, and the 27€ + VAT of the allocators’s price. As long as the cost allocator is not changed and it does not work, the company assumes that the radiator is on all the time and associates a very high consumption with it.
- Heat cost allocator reading price: the reading of the consumption of each allocator is done remotely every month, typically by a protocol known as RFID. The intermediary company charges 1.25 euros per allocator unit and month. That is, in a home with seven radiators, and a heating season of six months, there is an additional cost for the owner of more than 50 euros.
- Estimation: Cost allocators do not measure actual consumption. As explained above they are not able to do it. They simply estimate by measuring the temperature difference between the radiator and the exterior, by assigning a K factor based on the characteristics of each radiator.
- Invention: in some cases, for example a radiator near a bathtub, it is not possible to install the cost allocator due to the risk of habitual breakage due to humidity. In those cases, the allocator is not installed and consumption is just invented, which, in my opinion, gives very little credibility to the system. Of course, in that case they continue to charge the cost of reading / inventing the consumption of said radiator.
- Heat generated in the distribution pipes: the cost allocators are installed on the radiators, but a lot of energy is also consumed by the water distribution pipes. As this consumption cannot be measured, the company simply estimate it, which is like saying that they invent it, which has a greater impact on the idea that no one pays for what they actually spend.
- High cost even if the radiators are not turned on: in my community, adding the estimated consumption costs of the distribution pipes, plus the allocators reading fee, the monthly price amounts to more than € 65 even when not a single radiator has been turned on. Those who want to install this system to save because they are not at home, and think that this way they will not pay anything, are completely wrong.
- The radiators cannot be covered: as explained, the cost allocator measures the temperature difference between the radiator and the exterior. When the radiator is covered, normally by a typical cabinet that covers a radiator, the allocator does not measure temperatures correctly and assigns a very high consumption to said radiator.
- Cost allocator wich gets the sun: in line with the previous point, if by chance the cost allocator gets the outside sun in a way that confuses him in the measurement of temperatures, it can assign a very high consumption to the radiator, as if it were always on , although in reality it has always been off. When these installations are put into operation, it is typical that a neighbor receives a disproportionate bill that does not correspond at all to their actual consumption.
- Noise: the thermostatic heads that regulate the flow of water to adjust the temperature of the room, generate a very uncomfortable noise, enough to not even be able to watch TV. This is because you can hear how the water flow is permanently regulated and how it enters the radiator.
- Loss of efficiency: normally, buildings with central heating are well insulated from the outside, but little insulated between floors and floors. In this way, by turning on all the radiators at the same time, a uniform heating of the building is achieved very efficiently. On the other hand, when individualizing, if only the radiators of a home are turned on, the heat is dispersed between the adjoining floors on the sides and above and below, so that the energy consumption is very inefficient for the owner, because it does not transform into heat. This incurs a higher cost.
Individualizing a central heating system is discouraged due to the many disadvantages mentioned. In short, individualization is a bad idea because buildings with central heating system were built to be thermally optimal with such a system, and because individualization requires the incorporation of a ‘parasitic’ intermediary company that charges a significant amount of money that does not transform into heat.
If, despite everything, in a community they decide to individualize their central heating system, I strongly recommend opting for an intermediary company that places open source cost allocators. In this way, if the community decides to change the intermediary company that performs the reading of the allocators, it will not be necessary to change these devices, saving each neighbor a significant amount of money.