ᐅ Wall heating systems do not reach the desired temperature

Created on: 8 Dec 2021 20:22
E
EdelStoff
Hello everyone,

I need your help. We have the problem that we can’t get our bathroom properly warm. Due to the small underfloor heating area in the bathroom, three additional wall heaters were installed. Still, we can’t get the temperature above about 21 degrees Celsius (70°F). The calculation was based on 24 degrees Celsius (75°F). I have already switched off the EER and set the flow rate to the maximum (3 liters per minute). All other rooms easily reach their target temperature and are sometimes already at the minimum flow rate.

Do you have any other ideas on what could be done?

Thank you very much and best regards
D
driver55
11 Dec 2021 08:23
@TE: please share some pictures of the underfloor heating installation and the heating circuit valves (all flow rates).
E
EdelStoff
11 Dec 2021 15:55
face26 schrieb:

However, that’s not how the design was calculated.

Well, it really depends on the circumstances. The energy saving regulation (Energieeinsparverordnung) is not the same as KfW40.
I also follow the energy saving regulation, with 0.35 at a 21.5m (71 feet) room target. And that’s not driving me into financial trouble.
I also have offsets and recesses, plus a basement within the thermal envelope that I’m not currently heating, and so on.

Yes, 21.5m (71 feet) in the bathroom is also achievable with 0.35. I just haven’t tried lowering the heating curve yet.

@TomTom @driver55
Currently, I have the flow rates set back to the installer’s settings.

Distribution block with transparent tubes and orange connectors.

Metal distribution manifold with multiple transparent tubes and orange caps.


@edit:
I’ve attached another picture from the bathroom.

Underfloor heating pipes arranged in a spiral on top of insulation, prepared for screed.

Red heating pipes standing vertically against a brick wall in the shell construction, with brackets.

Red heating pipes running vertically along a brick wall during construction, with brackets.
D
driver55
11 Dec 2021 16:37
For a bathroom, I consider underfloor heating to be a "bad joke." It can never be 10 cm (4 inches) VLA. Of course, you have to run it with a supply temperature above 30 degrees Celsius (86°F).

I can barely see any flow rates; I’ll have to take a closer look later.
I’ll upload a picture of our underfloor heating in the bathroom later for comparison.
Mycraft11 Dec 2021 17:02
I guess the bathroom also has an exterior wall? On the floor, maybe it should have been 5cm (2 inches), since the area is quite limited.
driver55 schrieb:

That can never be 10 cm (4 inches) VLA.
Well, it’s actually around 10-12cm (4-5 inches). You can quite clearly see it based on the grid. But that doesn’t change the fact that it’s too little for a bathroom. The heat output is simply too low.
E
EdelStoff
11 Dec 2021 17:08
Yes, the bathroom has two exterior walls. There is also some underfloor heating at the front and back. Unfortunately, I couldn’t find a picture quickly. The grid is 10cm (4 inches), so I think the VLA is approximately correct.
D
driver55
11 Dec 2021 18:26
EdelStoff schrieb:

Yes, the bathroom has two exterior walls. There is also a section of underfloor heating at the front and back. Unfortunately, I couldn’t quickly find a picture. The grid spacing is 10cm (4 inches), so I think the VLA is roughly correct.
Exactly, just approximately.
You could easily have installed twice the length, or needed to, and then you wouldn’t be in this situation now. 😉

Here is a picture from our “mini bathroom” (8.7 m² (94 sq ft) floor area, according to DIN standard 7 m² (75 sq ft)) from 2009.

Underfloor heating pipes laid spirally on a wooden frame in a shell construction.