Underfloor heating : The most common installation mistakes

If the underfloor heating is set up and adjusted just once, it will keep the apartment at the same temperature.

Usually, mistakes don’t happen very often. Because the worst mistakes already happen when underfloor heating is being put in. The first signs of a problem with the underfloor heating system are:

  • Even though there is underfloor heating, the rooms aren’t warm.
  • The floors in each room only get warm in different places.
  • Moisture stains appear.


Not all damage to underfloor heating is obvious at first glance. Humidity is different. Most mechanical damage to pipelines happens during conversion or renovation work. It rarely happens when the pipelines are first put in place.

If the underfloor heating system loses water or pressure, the pipes’ damage is fixed immediately or found before the system is turned on.

If it does start to rain, move quickly. First, the distributor should be used to turn off the heating circuit in question. This keeps water from leaking and the underfloor heating from not working.

Then, the point in the floor structure that goes with it must be shown. The broken section of the pipe is cut out and replaced with a new pipe with two connections to connect it to the existing pipe system.

The rooms don’t get warm

If the rooms aren’t really warm, even though they have underfloor heating, or they don’t feel comfortable, this can be caused by a few things:

Cable distances are too large

You shouldn’t leave too much space between the pipes when you lay them. The room won’t get warm enough after that.

The heating load calculation for the rooms is now wrong, and the flow temperature of the heating system needs to be raised. This makes the heating system work less well.

Incorrect pipe diameter

Using the wrong pipe diameter can lead to a lot of problems. The whole heating system is affected when the pipes aren’t the right size.

It changes the flow rate, the throughput, and, in the end, the amount of heat given off. All of the calculations for the hydraulic balance, the space heating requirement, and the heating system settings are no longer correct.

Installation based on empirical values, often done when building a single-family home or making home improvements, is always risky.

This is where heating experts come in, and you should follow the numbers they give you.

The lines are too long

When putting the pipes down, you should consider how long they are. If the length of each heating circuit is too long or if the lengths of the different heating circuits are very different, this will cause hydraulic problems.

Too much water moves through the shorter heating circuit, while not enough moves through the longer heating circuit.

When the length of a heating circuit is too long, there is too much cooling between the flow and the return. If possible, all of the pipes for the underfloor heating should be laid at the same length.

The heating specialist will tell you the longest length per heating circuit. Also, heating circuits with the same length make it easier for the whole heating system to be hydraulically balanced.

The floors in individual rooms only become unevenly warm

If the rooms aren’t really warm in some parts of the floor or don’t feel comfortable, this can be caused by one of two things:

Missing edge zones

If the air or surface temperature is cooler on the outer walls of a room or in front of floor-to-ceiling windows and patio doors, something is wrong with the edge zones of the underfloor heating.

So that these thermal bridges don’t happen, the pipes for the underfloor heating are laid in these areas more narrowly than in the rest of the room.

Because the pipes are closer together, the surface temperatures in the edge zones will be higher. When putting in the underfloor heating, you need to pay attention to how close the pipes are to each other in the edge zones.

Insulate supply lines

At the heating circuit manifold, the air or surface temperature is much higher than in the rest of the room. This is because all the pipes for underfloor heating are put together at the heating circuit distributor.

So, the distributor is usually set up in the corridor or hallway. Since a small plank doesn’t need much heat, it can also overheat.

Since you can’t control the temperature in the area of the heating circuit distributor, heating experts suggest insulating the heating lines to the rooms in this area or integrating them into the insulating layer of the floor.