ᐅ Efficiency of Heliotherm Flat Plate Collectors

Created on: 18 Aug 2016 12:27
M
Meneike
M
Meneike
18 Aug 2016 12:27
Hello, we are quite confused and hope you can help us. The developer Aktuell Bau wants to install a 180m2 (1,937 sq ft) large collector field with 8 external loops for extracting geothermal energy using ground collectors. Our living area is also 180m2 (1,937 sq ft). Everywhere we read and hear that at least 1.5 times the collector area is required. However, Aktuell Bau says that due to their highly efficient system from Heliotherm, see link:

it is not necessary, and they will definitely only install 180m2 (1,937 sq ft). What do you think? Is this correct?

Thank you very much for your help!

Best regards, Mareike
W
Wastl
18 Aug 2016 13:17
Requirement:

  • a sufficient contiguous undeveloped plot area around 1.5 times the heated floor area of the building
S
Saruss
18 Aug 2016 18:22
No matter how efficient the heating system is, heat energy is extracted from the ground. This causes the ground to cool down. If the collected area is too small, the ground may freeze, potentially heave, or the brine temperature will drop significantly.

In fact, a particularly inefficient brine heat pump requires less collector area because less energy is drawn from the ground, and more electricity is used instead, but that’s not what you want ;p
Edit: It sounds like a direct expansion system, is that correct? These systems involve maintenance costs due to the amount of refrigerant used.
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T
taxpayer
30 Aug 2016 21:04
Hello,

so... the company regularly installs direct expansion systems. This means it is not a brine-to-water heat pump. This way, they apparently achieve higher performance in a small area… Please note, this is just my non-expert understanding.
S
Saruss
30 Aug 2016 21:18
See my post about this. It is not possible to extract unlimited energy from a certain area (volume) without resulting disadvantages.

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C
Carsten-le
22 Nov 2016 12:34
@Meneike: Did you choose the Heliotherm system?

@Saruss: Yes, the system Meneike is referring to uses a direct evaporator. What kind of maintenance costs related to the refrigerant should be expected? I don’t need to maintain my refrigerator either (which works on the same refrigerant principle, just reversed).
Regarding "You cannot extract unlimited energy from a certain area (volume) without causing disadvantages."
Are the disadvantages just a slightly cooler ground in that area, or does the performance of the direct evaporator surface or the heating system decrease over time, especially during a longer cold winter? (Compared to a deep borehole)