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
Neubau2020
Hello,
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?
We are currently facing the difficult decision of which heating system is the best fit for us. We need to choose one of the three options:
1.) Proxon (air source heat pump)
2.) Air-to-water heat pump with underfloor heating and separate controlled ventilation system
3.) Ground source heat pump with underfloor heating and separate controlled ventilation system
Gas is not an option since no gas lines are being installed in the new development area.
For option 1), the comparatively low initial costs are certainly a major advantage over options 2) and 3). However, we are discouraged mostly by the predominantly negative experiences shared on various online forums (mainly: insufficient heating power, high running costs due to high electricity consumption).
Basically, we are leaning more towards option 2) or 3). But even here, we often read about the significant sluggishness of hydronic (water-based) radiant heating systems. Can anyone share their experience with this? How should we understand this?
Does this sluggishness mean, for example, that the house cools down noticeably during a rapid outdoor temperature drop of 10°C (18°F) because the underfloor heating cannot keep up?
Or does sluggishness rather refer to the time it takes to increase the temperature of a room (for example, raising a bathroom from 23°C to 25°C (73°F to 77°F)) over several hours?
Put differently: Can the underfloor heating maintain a constant 23°C (73°F) in the bathroom and 21°C (70°F) in the other rooms regardless of the outside temperature?
1.) Proxon (air source heat pump)
2.) Air-to-water heat pump with underfloor heating and separate controlled ventilation system
3.) Ground source heat pump with underfloor heating and separate controlled ventilation system
Gas is not an option since no gas lines are being installed in the new development area.
For option 1), the comparatively low initial costs are certainly a major advantage over options 2) and 3). However, we are discouraged mostly by the predominantly negative experiences shared on various online forums (mainly: insufficient heating power, high running costs due to high electricity consumption).
Basically, we are leaning more towards option 2) or 3). But even here, we often read about the significant sluggishness of hydronic (water-based) radiant heating systems. Can anyone share their experience with this? How should we understand this?
Does this sluggishness mean, for example, that the house cools down noticeably during a rapid outdoor temperature drop of 10°C (18°F) because the underfloor heating cannot keep up?
Or does sluggishness rather refer to the time it takes to increase the temperature of a room (for example, raising a bathroom from 23°C to 25°C (73°F to 77°F)) over several hours?
Put differently: Can the underfloor heating maintain a constant 23°C (73°F) in the bathroom and 21°C (70°F) in the other rooms regardless of the outside temperature?
Yes, it works if it has been properly calculated and dimensioned using a room-specific heating load calculation.
Then, for example, with your requirements (bathroom warmer than the rest), it could turn out that due to the small floor heating area in the bathroom, an additional wall surface needs to be planned as wall heating, or alternatively, the commonly used purely electric towel radiator would be necessary.
Or the standard heating renovation installer sets everything to 23°C (73°F) and reduces the flow rate to the other rooms, which would not be optimal from an energy or hydraulic perspective...
Then, for example, with your requirements (bathroom warmer than the rest), it could turn out that due to the small floor heating area in the bathroom, an additional wall surface needs to be planned as wall heating, or alternatively, the commonly used purely electric towel radiator would be necessary.
Or the standard heating renovation installer sets everything to 23°C (73°F) and reduces the flow rate to the other rooms, which would not be optimal from an energy or hydraulic perspective...
In general, underfloor heating takes some time because the screed needs to warm up first. And once it is warm, it stays warm for a while.
Especially when hosting a party with many people, you usually heat as you normally would, so that the first guests don’t feel cold. Then, when many guests arrive, their body heat adds extra warmth. A regular radiator can simply be turned off quickly. With underfloor heating, this doesn’t make much sense because by the time the screed cools down, the guests have usually already left.
This is just one example. With an active ventilation system, you of course have additional advantages. Since we currently don’t have ventilation, we regularly do short bursts of airing to bring in fresh air, which is necessary anyway.
The point is that underfloor heating is slow to respond. You can’t quickly turn it on and off. Depending on the thickness of the screed, it takes some time. Therefore, the temperature is usually kept stable. This works well for us; we maintain 21°C (70°F) throughout the house, just a bit warmer in the bathroom.
Since all new buildings are well insulated, sudden drops in temperature don’t have much effect. The indoor temperature doesn’t drop quickly. Heating a room within 30 minutes won’t work (without additional heating).
Especially when hosting a party with many people, you usually heat as you normally would, so that the first guests don’t feel cold. Then, when many guests arrive, their body heat adds extra warmth. A regular radiator can simply be turned off quickly. With underfloor heating, this doesn’t make much sense because by the time the screed cools down, the guests have usually already left.
This is just one example. With an active ventilation system, you of course have additional advantages. Since we currently don’t have ventilation, we regularly do short bursts of airing to bring in fresh air, which is necessary anyway.
The point is that underfloor heating is slow to respond. You can’t quickly turn it on and off. Depending on the thickness of the screed, it takes some time. Therefore, the temperature is usually kept stable. This works well for us; we maintain 21°C (70°F) throughout the house, just a bit warmer in the bathroom.
Since all new buildings are well insulated, sudden drops in temperature don’t have much effect. The indoor temperature doesn’t drop quickly. Heating a room within 30 minutes won’t work (without additional heating).
D
DerGuteTon8 Jun 2020 08:12Earlier in the thread, passive cooling was briefly mentioned. We are installing an air-to-water heat pump, which apparently can also provide active cooling, at least according to some of the marketing claims. It’s a Daikin Altherma 3 R. Daikin makes good equipment.
I didn’t choose it because of the cooling feature, but it’s a useful side note. Does an air-to-water heat pump’s cooling function actually work well? Does it basically just mean a cooler floor in the summer? (We have underfloor heating installed)
I didn’t choose it because of the cooling feature, but it’s a useful side note. Does an air-to-water heat pump’s cooling function actually work well? Does it basically just mean a cooler floor in the summer? (We have underfloor heating installed)
DerGuteTon schrieb:
I didn’t choose it for the cooling function, but that’s a small side benefit. A cooling function on an air-to-water heat pump – is that any good? Does it basically just mean a cooler floor in summer? (Underfloor heating installed)It’s definitely not air conditioning, but you can lower the temperature by a few degrees.
Honestly, I’m not a fan if it runs through an air-to-water heat pump, because it uses quite a bit of electricity. In that case, you might consider installing an actual air conditioner. For a brine-to-water heat pump, where you can cool passively almost for free, I think it’s a very sensible concept, both environmentally and economically. But for an air-to-water heat pump… well, I’m undecided, leaning towards it not being worthwhile…
@dab_dab and @Teemoe86:
Thank you for your replies! So, if I decide to install underfloor heating, would I need to cover the additional heat demand in the bathrooms with, for example, an electric towel warmer and in the living area with a fireplace?
How is it with the Proxon system? Is it similarly slow to respond?
What kind of electricity consumption can be expected? In various forums, I have seen very different consumption figures, sometimes between 3,000 and 4,000 kWh per year and sometimes as high as 7,000 kWh.
Overall, I find the topic of Proxon’s energy consumption quite unclear and in my opinion, it represents a significant risk—especially since we are planning to build a “55” house...
Has anyone gained any personal experience with this?
Thank you for your replies! So, if I decide to install underfloor heating, would I need to cover the additional heat demand in the bathrooms with, for example, an electric towel warmer and in the living area with a fireplace?
How is it with the Proxon system? Is it similarly slow to respond?
What kind of electricity consumption can be expected? In various forums, I have seen very different consumption figures, sometimes between 3,000 and 4,000 kWh per year and sometimes as high as 7,000 kWh.
Overall, I find the topic of Proxon’s energy consumption quite unclear and in my opinion, it represents a significant risk—especially since we are planning to build a “55” house...
Has anyone gained any personal experience with this?
Similar topics