ᐅ Air-to-air heat pump vs. air-to-water heat pump vs. trench ground collector – Differences
Created on: 12 Dec 2019 10:33
N
Neubau2020N
Neubau202012 Dec 2019 10:33Hello,
I am currently trying to decide how the heating energy should be generated.
Here in the forum, I came across the horizontal ground loop collector, which I find very interesting. In conversations with two prefabricated house suppliers, I mentioned that I am considering generating energy with a horizontal ground loop collector. Both times, the response was, "We’ve heard of horizontal ground loop collectors, but never installed one."
One offer included an air-to-water heat pump (Luxhaus KfW55), and the other included an air-to-air heat pump with controlled residential ventilation (Streif Haus KfW40). The house will have two levels, no basement, around 190 m² (2,045 sq ft), on a fairly flat plot with no special features.
I am wondering how the horizontal ground loop collector differs technically and in price from the air-to-water heat pump.
Is the technology inside the house the same, or are there other factors to consider, such as system size and design?
Is the main difference simply that instead of the external unit of the air heat pump, I install the trench and lay the pipes?
What is the price difference?
What about the long-term difference in energy consumption? The air heat pump needs to run continuously on electricity to draw in air—how does it work with geothermal energy from the horizontal ground loop in this regard?
Lastly, a question regarding the air-to-air heat pump:
The sales representative from Streif Haus said that if I wanted to switch from the air-to-air heat pump to an air-to-water heat pump, it would cost about 10,000 euros more. Is that a realistic estimate?
I am currently trying to decide how the heating energy should be generated.
Here in the forum, I came across the horizontal ground loop collector, which I find very interesting. In conversations with two prefabricated house suppliers, I mentioned that I am considering generating energy with a horizontal ground loop collector. Both times, the response was, "We’ve heard of horizontal ground loop collectors, but never installed one."
One offer included an air-to-water heat pump (Luxhaus KfW55), and the other included an air-to-air heat pump with controlled residential ventilation (Streif Haus KfW40). The house will have two levels, no basement, around 190 m² (2,045 sq ft), on a fairly flat plot with no special features.
I am wondering how the horizontal ground loop collector differs technically and in price from the air-to-water heat pump.
Is the technology inside the house the same, or are there other factors to consider, such as system size and design?
Is the main difference simply that instead of the external unit of the air heat pump, I install the trench and lay the pipes?
What is the price difference?
What about the long-term difference in energy consumption? The air heat pump needs to run continuously on electricity to draw in air—how does it work with geothermal energy from the horizontal ground loop in this regard?
Lastly, a question regarding the air-to-air heat pump:
The sales representative from Streif Haus said that if I wanted to switch from the air-to-air heat pump to an air-to-water heat pump, it would cost about 10,000 euros more. Is that a realistic estimate?
Neubau2020 schrieb:
The Streif house salesperson said, in response to my question about how much more it would cost to install an air-to-water heat pump instead of an air-to-air heat pump, that the additional cost would be around 10,000 euros. Is that realistic?That could be accurate, although the extra cost is not primarily due to the different heat pump itself, but rather the underfloor heating system, which is omitted when using the air-to-air heat pump.
Trench collector + brine-water heat pump is (a rough calculation, since I did the work myself) cheaper than an air-water heat pump because the subsidy is significantly higher. For example, I built the trench collector myself, which cost me less than €2,500 (including pipes, manifold, rental for excavator and operator, house entries, etc.), but I received a €5,500 subsidy (so I effectively got the collector for free plus €2,000 extra pocket money).
Advantages: Passive cooling in summer is possible (almost free, not a huge effect, but definitely a benefit during warm periods), higher efficiency compared to an air-water heat pump, durability (the collector itself will outlast you by far; brine-water heat pumps are said to have longer lifespans since the heat transfer medium is more stable), and what was very important to us: no ugly outdoor unit like on an air-water heat pump! (Air-air heat pumps were out of the question anyway since they are significantly less efficient compared to air-water heat pumps).
Regarding your electricity question: A brine-water heat pump also runs on electricity, but it generates more heat energy per kWh of electricity.
Advantages: Passive cooling in summer is possible (almost free, not a huge effect, but definitely a benefit during warm periods), higher efficiency compared to an air-water heat pump, durability (the collector itself will outlast you by far; brine-water heat pumps are said to have longer lifespans since the heat transfer medium is more stable), and what was very important to us: no ugly outdoor unit like on an air-water heat pump! (Air-air heat pumps were out of the question anyway since they are significantly less efficient compared to air-water heat pumps).
Regarding your electricity question: A brine-water heat pump also runs on electricity, but it generates more heat energy per kWh of electricity.
An air-to-air heat pump does not include underfloor heating.
Fresh air is drawn in, heated through heat recovery, and any additional warmth needed is generated by electricity at the air outlet, similar to a small hairdryer. Domestic hot water is produced solely by electricity.
Because underfloor heating is missing, this can save up to 10,000 euros.
Air-to-water heat pump
The air-to-water heat pump has a refrigerant circuit and a compressor. It works like a refrigerator but in reverse. Usually, underfloor heating is connected. Hot water is also generated by the pump. Only at very low temperatures does the system’s capacity become insufficient.
A trench collector is more efficient. How much this saves in euros is unknown.
I would not install a pure air-to-air heat pump.
Air-to-water heat pumps can also be installed without an external unit.
Fresh air is drawn in, heated through heat recovery, and any additional warmth needed is generated by electricity at the air outlet, similar to a small hairdryer. Domestic hot water is produced solely by electricity.
Because underfloor heating is missing, this can save up to 10,000 euros.
Air-to-water heat pump
The air-to-water heat pump has a refrigerant circuit and a compressor. It works like a refrigerator but in reverse. Usually, underfloor heating is connected. Hot water is also generated by the pump. Only at very low temperatures does the system’s capacity become insufficient.
A trench collector is more efficient. How much this saves in euros is unknown.
I would not install a pure air-to-air heat pump.
Air-to-water heat pumps can also be installed without an external unit.
Air-to-air heat pumps are the biggest scam since the invention of the surprise egg and should be avoided. They are only outdone by exhaust air heat pumps.
Air-to-water heat pumps represent the current state of technology and can work well if everyone involved (including the end user) knows what they are doing. However, with poor design and use, they can become a money pit. Taking time to thoroughly understand the subject is an absolute must.
The trench collector is excellent, a direct competitor to other ground-source systems, but very simple and cost-effective to install. If your builder agrees to use it, you should document and share it on their website as a thank you. We didn’t do this simply because we heard about it too late. This is something from which builders can learn and then offer as a unique selling point to their future clients.
Air-to-water heat pumps represent the current state of technology and can work well if everyone involved (including the end user) knows what they are doing. However, with poor design and use, they can become a money pit. Taking time to thoroughly understand the subject is an absolute must.
The trench collector is excellent, a direct competitor to other ground-source systems, but very simple and cost-effective to install. If your builder agrees to use it, you should document and share it on their website as a thank you. We didn’t do this simply because we heard about it too late. This is something from which builders can learn and then offer as a unique selling point to their future clients.
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