ᐅ Which brine-to-water heat pump: Viessmann, Nibe, or Stiebel WPE-I 10 H?
Created on: 10 Mar 2024 08:32
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Alrico1Hello,
my two-family house (KfW40 standard, over 300 sqm (3,230 sq ft) of living space with underfloor heating) will be connected to cold local district heating (raw water), and the question is which brine-to-water heat pump (with passive cooling function) is optimal. I can freely choose between Viessmann, Nibe, or Stiebel. The heating capacity should be at least 9 kW. The installer initially recommended a Stiebel brine-to-water heat pump WPE-I 10 H 400 Plus with a sound power level of 44 dB(A). Are there any experiences with this or good alternatives?
Good luck, Alrico1
my two-family house (KfW40 standard, over 300 sqm (3,230 sq ft) of living space with underfloor heating) will be connected to cold local district heating (raw water), and the question is which brine-to-water heat pump (with passive cooling function) is optimal. I can freely choose between Viessmann, Nibe, or Stiebel. The heating capacity should be at least 9 kW. The installer initially recommended a Stiebel brine-to-water heat pump WPE-I 10 H 400 Plus with a sound power level of 44 dB(A). Are there any experiences with this or good alternatives?
Good luck, Alrico1
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RotorMotor10 Mar 2024 09:26Why so much power?
Yes, 300m² (3,229 ft²) is not a small house, but KFW40 is very efficient.
What temperature or temperature range does your low-temperature district heating network operate at?
With oversized heat pumps, you always have the problem of short cycling, which leads to early wear.
Yes, 300m² (3,229 ft²) is not a small house, but KFW40 is very efficient.
What temperature or temperature range does your low-temperature district heating network operate at?
With oversized heat pumps, you always have the problem of short cycling, which leads to early wear.
Except for heating installers, most people have little experience with multiple brands and models.
Have you received a proper heating load calculation? 9 kW could possibly be oversized despite the floor area – to me, that sounds like a rough estimate based on 300 sqm (3229 sq ft) * 30 kWh per sqm KfW40 limit. It might be correct, but not necessarily.
If, for example, 6 to 7 kW are more realistic, you could also consider a Nibe S1155-6 PC, which is a bit more efficient and has integrated cooling without additional components. It can be “overclocked” up to 7.5 kW if needed. However, it still uses older refrigerants, which might be an issue for you.
If 9 kW is really needed, then in my opinion Nibe is out, since they only offer 6 kW / 12 kW / 16 kW models. In that case, Stiebel is certainly not a bad alternative.
What about the controlled mechanical ventilation? Should it be connected to the heat pump, or implemented as two separate systems?
Have you received a proper heating load calculation? 9 kW could possibly be oversized despite the floor area – to me, that sounds like a rough estimate based on 300 sqm (3229 sq ft) * 30 kWh per sqm KfW40 limit. It might be correct, but not necessarily.
If, for example, 6 to 7 kW are more realistic, you could also consider a Nibe S1155-6 PC, which is a bit more efficient and has integrated cooling without additional components. It can be “overclocked” up to 7.5 kW if needed. However, it still uses older refrigerants, which might be an issue for you.
If 9 kW is really needed, then in my opinion Nibe is out, since they only offer 6 kW / 12 kW / 16 kW models. In that case, Stiebel is certainly not a bad alternative.
What about the controlled mechanical ventilation? Should it be connected to the heat pump, or implemented as two separate systems?
Thank you for the feedback.
The cold district heating network operates with a raw water temperature of about 10 to 12°C (50 to 54°F).
The installer assumed a higher capacity based on the (potential) consumers. However, I will still receive a proper heating load calculation.
For the controlled residential ventilation, I am considering an independent system: Meltem heat recovery II, but apparently not many installers here offer it, and understandably, they tend to propose the well-known ventilation brand.
Otherwise, the price difference for the Stiebel WPE-I 10 H 400 Plus, with or without the additional cooling function components, was around 3,000 EUR. I am still wondering if I really need this passive cooling. I am building with a 24cm (9.5 inch) calcium silicate exterior wall plus external thermal insulation composite system (ETICS).
The cold district heating network operates with a raw water temperature of about 10 to 12°C (50 to 54°F).
The installer assumed a higher capacity based on the (potential) consumers. However, I will still receive a proper heating load calculation.
For the controlled residential ventilation, I am considering an independent system: Meltem heat recovery II, but apparently not many installers here offer it, and understandably, they tend to propose the well-known ventilation brand.
Otherwise, the price difference for the Stiebel WPE-I 10 H 400 Plus, with or without the additional cooling function components, was around 3,000 EUR. I am still wondering if I really need this passive cooling. I am building with a 24cm (9.5 inch) calcium silicate exterior wall plus external thermal insulation composite system (ETICS).
Regarding passive cooling, with our Novelan system it was “only” about a 1,500€ (approximately $1,500) additional cost and was installed. We have had it activated since the beginning (1.5 years ago), but unfortunately, I cannot say how it would perform if deactivated.
We also have 24cm (9.5 inches) and 16cm (6.3 inches) aerated concrete walls plus external thermal insulation composite system (ETICS) and find it sufficiently cool in summer. I believe shading (roller shutters or blinds) supports cooling more effectively than any retrofit cooling system.
Oh, and the mechanical ventilation with heat recovery naturally also pushes warm summer air into the house, so that combination is not ideal. However, the advantages (no mosquitoes or flies, clean air, no need to open windows) clearly outweigh that.
We also have 24cm (9.5 inches) and 16cm (6.3 inches) aerated concrete walls plus external thermal insulation composite system (ETICS) and find it sufficiently cool in summer. I believe shading (roller shutters or blinds) supports cooling more effectively than any retrofit cooling system.
Oh, and the mechanical ventilation with heat recovery naturally also pushes warm summer air into the house, so that combination is not ideal. However, the advantages (no mosquitoes or flies, clean air, no need to open windows) clearly outweigh that.
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