Adjust underfloor heating - why this is important

The optimal setting of underfloor heating is essential for energy-saving and effective operation of underfloor heating. In many cases, it is not design errors of the system, but installation errors in the system, which lead to high energy consumption and low efficiency of the heater. Read all about setting a floor heating system here.

Important settings

Some values ​​in the system are determined by the dimensions of the underfloor heating, and should not be changed. Changes require an experienced specialist who knows the heating, or at least has a heating plan and the necessary calculations for the dimensioning available.

Hydraulic balancing

Every underfloor heating needs (as well as a radiator heating) a so-called hydraulic adjustment.

This determines which pressure should prevail in which heating circuit. The pressures in the different heating circuits are not the same. The distribution of the individual pressure values ​​depends on different factors:

  • the required heat output in the respective heating circuit (heating heat demand!)
  • the volume flows in the individual heating circuits
  • the pipe length in the respective heating circuit
  • the underground below the underfloor heating in the respective heating circuit
  • the floor covering and the covering thickness in the respective heating circuit
  • the respectively set flow temperature of the heater

If possible (if not necessary), the values ​​of the hydraulic balancing should not be changed, but the settings should be left to a heating contractor.

Other important settings for underfloor heating

flow temperature

The flow temperature for underfloor heating is significantly lower than for a radiator heater. This is because the underfloor heating is a radiant heater that gives off its heat directly via heat radiation. In contrast, the radiator heating is a so-called convection heating, which is intended to heat the room air.

While the flow temperature for radiator heating must always be above 55° C, modern underfloor heating systems normally set a flow temperature of no more than 35° C. It can be chosen lower in some cases for reasons of economy.

Return temperature

The return temperature is the temperature of the water flowing back from the heating pipes. Changes in the flow temperature always affect the return temperature, and vice versa.

By adjusting the return temperature, you can also control the power delivery of the heating up to a certain degree. However, settings should only be changed by the specialist who knows the system and its values.


The spread is the temperature difference between flow and return temperatures. It is usually given in Kelvin in technical plans and calculations. When specifying temperature differences, however, the values ​​in Kelvin correspond 1: 1 to the values ​​in° C.

If the flow temperature is 35° C, and the return temperature is 32° C then the spread is exactly 3° C or 3 K.


The flow rate is the amount of water that flows through the heating pipes of a particular heating circuit. The term "volume flow" is thus not always the same, because it is defined technically slightly different.

The changes in the flow rate change the heat output of individual heating circuits. In principle one can say: the higher the flow, the more power in the respective heating circuit.

The determination of the flow rate for the individual heating circuits is a matter of so-called "hydraulic balancing". In addition, however, all other performance values ​​are always to be taken into consideration, since they have an influence (flow and return temperature, spread, pipe lengths, etc.).

Settings as a layman

In most cases (if there are no room thermostats) you can only set the room temperature control.

This is done via the adjustment valves for the temperature control. On the other hand, you should better keep your fingers away from the hexagon bolts, as they are used solely for hydraulic balancing. Making changes here without planning can be problematic if you do not act purposefully.

To test the heater and roughly regulate it, you can proceed as in the instructions below. Then let the heating pass through.

But you should not make any changes to the flow temperature and spread, as these values ​​are a matter of calculation. Only the specialist company can adjust this correctly.

Quick adjustment - step by step

  • underfloor heating
  • Hexagon key in matching size

1.Open all setting controls

Fully open all valves for temperature control. Also open all hexagon adjusting screws fully. Hang a thermometer in each room. Wait two days, keeping the rooms always closed.


Check the temperatures after two days. For all rooms above the set temperatures, slowly close the hexagon bolts for the hydraulic adjustment. After a reasonable waiting time (hours to about 1 day), check how far the temperature has fallen. The setting should reach a temperature that is 1° C above the setpoint temperature.

3. Control room temperature

If setpoint temperature + 1° C is reached in all rooms, carefully adjust (!) With the temperature controllers until the desired setpoint temperature is reached in each room.

Tips & Tricks

Note: all set values ​​of the heater are connected! Changes in one value may result in adverse changes in another value, making the heating inefficient or less efficient. If you are not sure, always have the settings made by an experienced heating contractor who knows the particular underfloor heating system.

Video Board: How To Adjust your manifold Flow Rates