ᐅ Always colder in the attic than on the ground floor?

Created on: 6 Mar 2017 21:22
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Nafetsm
Hello,

we are currently struggling with our heating system. It is warm everywhere in the house—both on the ground floor and in the heated basement room—around 21-22°C (70-72°F). However, the temperature in all rooms in the attic is noticeably lower, usually about 2°C (3.6°F) difference. This is problematic because a) it is too cold and b) it also affects the bathroom.

We have already tried various measures. We adjusted the heating curve, the manufacturer’s service performed a firmware update, and the hydraulic balancing was done again... but the problem remains the same. The attic stays consistently about 2°C (3.6°F) cooler than the other floors. The heating technician said this is normal because of the many windows and that it always tends to be cooler in the attic. He advised us to simply increase the supply water temperature. But that can’t be the solution, right? Although this raises the temperature in the attic, we then have to lower the temperature on the ground floor because otherwise it becomes too hot. The 2°C (3.6°F) difference always stays the same. We have solid ceilings and walls, underfloor heating everywhere, and the room thermostats turned up fully.

Is this really normal, or is the heating technician just trying to sell us that because he has no other ideas? What is your experience? Do you also have such temperature differences?
Mycraft23 Mar 2017 13:07
Nafetsm schrieb:
So poor insulation can be ruled out as the cause

It’s not about being good or bad... simply put, double the amount of exterior surface area, whether wall or roof, means twice the heat loss...
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Bieber0815
23 Mar 2017 20:50
The upper floor should also be capable of being heated above 21°C (70°F)! Most people have a bathroom or children’s room on the upper floor, and the temperature there is often above 21°C (70°F).
Nafetsm schrieb:
despite all measures, room temperature never exceeds 21.2°C (70.2°F)

I consider that a deficiency. Have you already reported this formally?

What else could be done:
- Have the heating load calculation and heating system sizing checked by an independent expert (is the theoretical data correct?). If okay, then:
- Measure the supply and return temperatures as well as the flow rate for each room to determine the actual heat input (under full load conditions). --> Is the issue insufficient heat input or heat losses?

Keep us updated; this is an interesting topic.
Musketier24 Mar 2017 07:22
Do you always use the same thermometer? I have noticed significant differences with both digital and analog types. Also, is the thermometer placed in the center of the room, or is it possibly mounted on an exterior wall?
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Knallkörper
24 Mar 2017 07:50
From my point of view, the issue must lie with the supply temperature. You say the flow rate is 2 liters/min (0.53 gallons/min), but increasing the supply temperature does not affect the surface temperature of the floor. That cannot be correct, regardless of the insulation.

So, check the thermometer reading.
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bierkuh83
24 Mar 2017 12:34
Your description doesn’t actually make sense in context. There must be a mistake somewhere. A couple more questions: How long did you keep the modified settings, and was the same type and thickness of screed poured throughout the entire house? Also, do you have the insulation under or above the concrete slab?
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bierkuh83
24 Mar 2017 12:54
I would honestly just suggest trying this as a test:
1. Record all settings
2. Close off the system at the bottom
3. Open at the top, set the building circulation pump to full power
4. Observe what happens (at least 24 hours)
5. Increase the flow temperature, then repeat step 4

Admittedly, this is a bit unconventional and it will get slightly cooler at the bottom, but it should provide some useful clues.

If this all seems too complicated or bothersome, you will need to involve your contractor or hire an external professional to continue troubleshooting...