ᐅ Exhaust air heat pump (F750) combined with solar thermal system (heating + domestic hot water) or ground source heat pump
Created on: 18 Jun 2019 11:09
D
DonTermi
Hello,
we are currently in the planning phase for a new single-family house (Energy Saving Ordinance standard, 36.5 cm (14 inches) aerated concrete; 125 m² (1,345 ft²) living area, underfloor heating). For several weeks, I have been thinking a lot about the heating system. Our construction company is recommending the Nibe approach. However, we had already chosen this builder beforehand because, thanks to a fortunate circumstance, we can acquire a "very affordable" plot of land.
Since I don’t want to use up our entire budget and want some flexibility for "unexpected costs," I am struggling to decide between:
- Nibe F750 (exhaust air heat pump with heat recovery) combined with a solar thermal system for heating and hot water (additional cost €11,000)
- Nibe F1255 ground-source heat pump (approx. €14,000 including earthworks, installation, etc.)
The combination of exhaust air heat pump + solar thermal is a somewhat more cost-effective solution than the ground-source heat pump. However, I’m not only considering the purchase price but also the operating and maintenance costs. I am initially disregarding the €4,000 BAFA subsidy for the ground-source system, as I would still have to finance the full amount upfront.
From my perspective, the majority of energy for a heat pump system is used for heating and hot water. I am aware of the many controversial discussions about exhaust air heat pumps. That is why I would like to use solar thermal support (complete replacement in summer) for heating and hot water to reduce costs related to the exhaust air heat pump, as it can still provide water temperatures up to 45°C (113°F) during the cold season.
For me, as mentioned, the economic aspect is important. I look forward to your opinions. Perhaps someone already has experience to share...
we are currently in the planning phase for a new single-family house (Energy Saving Ordinance standard, 36.5 cm (14 inches) aerated concrete; 125 m² (1,345 ft²) living area, underfloor heating). For several weeks, I have been thinking a lot about the heating system. Our construction company is recommending the Nibe approach. However, we had already chosen this builder beforehand because, thanks to a fortunate circumstance, we can acquire a "very affordable" plot of land.
Since I don’t want to use up our entire budget and want some flexibility for "unexpected costs," I am struggling to decide between:
- Nibe F750 (exhaust air heat pump with heat recovery) combined with a solar thermal system for heating and hot water (additional cost €11,000)
- Nibe F1255 ground-source heat pump (approx. €14,000 including earthworks, installation, etc.)
The combination of exhaust air heat pump + solar thermal is a somewhat more cost-effective solution than the ground-source heat pump. However, I’m not only considering the purchase price but also the operating and maintenance costs. I am initially disregarding the €4,000 BAFA subsidy for the ground-source system, as I would still have to finance the full amount upfront.
From my perspective, the majority of energy for a heat pump system is used for heating and hot water. I am aware of the many controversial discussions about exhaust air heat pumps. That is why I would like to use solar thermal support (complete replacement in summer) for heating and hot water to reduce costs related to the exhaust air heat pump, as it can still provide water temperatures up to 45°C (113°F) during the cold season.
For me, as mentioned, the economic aspect is important. I look forward to your opinions. Perhaps someone already has experience to share...
A brief update from my side... We have now decided to invest the additional €14,000 in a brine ground source heat pump. To my surprise, the offer even includes the ground drilling. Until now, I had always assumed a horizontal collector or trench collector would be used. Therefore, we are happy to accept the extra costs.
guckuck2 schrieb:
Well, for 14,000€ you get the heat pump including drilling. Complete, not as an extra charge. That includes not only the ground drilling and heating system, but also the extension for heat recovery (central controlled ventilation system for living spaces).
We have the F750 installed and are very satisfied with it. However, as always, the details matter. Solar thermal systems can only save you about 70 kWh of electricity during the summer months, which is roughly 14 EUR per month. In winter, the solar thermal system provides around 20°C (68°F), so it doesn’t really help much. Depending on the operator and billing model, I would recommend a photovoltaic system, but those typically cost an additional 10,000–15,000 EUR. The F750 operates very efficiently and economically. The problem is that very few people are familiar with this pump, so it often gets set up incorrectly. While with other pumps you usually try to avoid too many operating cycles, the F750 should ideally run almost continuously in winter. Since it’s a highly efficient inverter-driven system, it runs at about 100–1,300 watts at 3–5°C (37–41°F) outdoor temperature, which even our photovoltaic system can handle on a cloudy winter day.
In principle, geothermal heat pumps have a higher COP and are therefore more efficient. Here, you just need to make sure you have a proper borehole with the right medium. If you’re drilling in dry sand, the pump won’t be able to extract any heat. So, the composition of the ground is extremely important for geothermal pumps.
If it helps, our COP—including the ventilation system, heating control, and photovoltaic control—is around 3.0–3.5. (Geothermal heat pumps should have a COP of 5 or higher.)
In principle, geothermal heat pumps have a higher COP and are therefore more efficient. Here, you just need to make sure you have a proper borehole with the right medium. If you’re drilling in dry sand, the pump won’t be able to extract any heat. So, the composition of the ground is extremely important for geothermal pumps.
If it helps, our COP—including the ventilation system, heating control, and photovoltaic control—is around 3.0–3.5. (Geothermal heat pumps should have a COP of 5 or higher.)
As the initiator of this thread, I wanted to give a brief update. We decided to go for the 13,600 € (about 14,800 USD) extra cost for a ground source heat pump with a ground probe.
Our Bafa application has already been processed, and we have received an approval notice for a 4,500 € (about 4,900 USD) grant.
Best regards
Our Bafa application has already been processed, and we have received an approval notice for a 4,500 € (about 4,900 USD) grant.
Best regards
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