Underfloor heating with warm and cold spots

Hello,

when considering the underfloor heating in the new building, my father-in-law recommended the underfloor heating from Athe-therm (he means the OptImus there).
In this system, metal plates are laid over the heating pipes to ensure a better distribution of heat.

He already did this himself a few years ago, especially because with the old underfloor heating from anno ducto there were cold and warm tiles. As a child, my wife used to slide around playing only on the warm tiles.

I think it is not as bad today as described here.
Now I asked my brother-in-law if they also have cold and warm spots, that is, if you can tell where a pipe runs and where not. He said in winter you can feel that by placing your hand on it.

My question is now: Is it normal with modern underfloor heating to have cold and warm spots? (this has nothing to do with the warmth of the ambient air, but only with the contact heat)

If this is nothing unusual, I will definitely include the Athe-therm principle in my considerations.

Normally, you shouldn't have any cold spots... even warm is only conditionally true for the floor. The floor should be evenly very, very slightly warm. If it is cold anywhere, no snakes are there.

Hello,

I think people have a wrong understanding of underfloor heating. The days of having 'warm' tiles are over since KFW 55/40. The energy demand that flows through the surface into the living space is usually so low that supply temperatures of 24, 25, 26 degrees are used (also optimal for heat pumps). That always feels cold!! If you are afraid of 'cold' spots on the floor, you simply lay pipes at a 10 cm spacing; then the temperature is definitely evenly distributed over the floor.

If you actually have warm/cold areas, then the pipes were saved on and, for example, a 20 cm grid was installed. To get the energy into the room, the supply temperature was turned up. So you had large pipe spacing and high supply temperatures, which led to warm/cold zones. The people who had that simply didn’t inform themselves in advance.

I built my first house with underfloor heating in 1994; the 10 cm spacing I demanded for the underfloor heating was something the heater at the time wanted to talk me out of. It would only be expensive and the house would also be warm with 20 cm...

There are no warm-cold zones!!! A few years ago a dishwasher leaked in that house, and holes had to be drilled into the screed for drying. They took thermal images of the floor to avoid drilling into the heating coils. You could clearly see how evenly the floor warmed up.

ok, good info about the spacing, I didn't know that until now.

Although it still doesn't seem to be standard to work with 10-15cm. From what I read, 10cm seems to be laid in bathrooms and on window fronts, otherwise 20cm in the rooms.
Others wrote again that you can't even feel the difference because the flow temperature is so low anyway that the tiles always feel cool.

Lower spacing probably leads to lower flow temperatures which should reduce energy costs. Although in this context only heat pumps are actually mentioned. But I assume that the potential energy savings also apply to a gas condensing boiler.

Then either like this (5-10-15cm spacing), or maybe still work with these thermal conductor plates. I could imagine that it comes down to the same thing. But I don't know!
If applicable, maybe someone else has experience with the dry systems and thermal conductor plates, whether you can also achieve lower flow temperatures with a larger spacing (20cm) this way.

The not feeling anything is only subjective! We have no pipes in the shower area and believe me you can notice it very clearly.

So, the smaller installation spacing leads to lower flow temperatures regardless of the source (heat pump, gas, oil, wood).

In my current house, I heat with wood, solar thermal, and gas condensing boiler, all feeding into a buffer tank from which the underfloor heating and domestic hot water draw energy. I have laid 5 cm in the bathroom and 10 cm everywhere else.

Personally, I do not see the metal sheets as an advantage. I think flowing screed that perfectly surrounds the pipes is more effective. The additional cost for the pipes is negligible compared to the other costs. I have 2500 m on the ground floor, which cost around €1200 for the pipes. Since I don’t know how the technology will develop, I would definitely install pipes closer together so that in the future you can easily switch the energy source. If I want to switch from gas to heat pump in 15 years, I’ll have that option without having to modify the screed.

But that is just my very personal approach.