ᐅ Would you choose an air source heat pump again? I am looking for alternatives to air source heat pumps.
Created on: 9 Apr 2015 19:45
X
xycrazy
Hi everyone,
we are facing a decision regarding the heating system for our new build! The house has 160m² (1,722 sq ft) of living space plus a basement apartment with about 80m² (861 sq ft).
I have to admit, it’s not easy. Initially, I was leaning towards an air-to-water heat pump, then we considered pellets for a while, and now we are back to the air-to-water heat pump. Meanwhile, I’ve also read about trench collectors, which, if installed by yourself, can save the high investment costs of geothermal systems and make them similarly priced to air-to-water heat pumps.
You often read that air-to-water heat pumps only work well if everything is properly sized and the winter is relatively mild. I would be interested in hearing generally if you would choose an air-to-water heat pump again and what your monthly electricity consumption is. I’m concerned about heating with electricity. In the past, night storage heaters were criticized, and now we are supposed to heat with electricity again? Even though the air-to-water heat pump is much more efficient, I still feel uneasy because of the dependency on electricity prices and all the horror stories about very high energy bills.
By the way, we were recommended the Wolf BWL-1-A (outdoor installation). It is supposed to be very, very quiet but not exactly small. Does anyone have experience with it?
What would you choose as an alternative to the air-to-water heat pump? Gas? That’s basically not an option for me. I’m not comfortable having a gas line in the house, unless you have good arguments for it.
Other alternatives? Fireplace with buffer tank? Pellets?
Looking forward to your answers.
we are facing a decision regarding the heating system for our new build! The house has 160m² (1,722 sq ft) of living space plus a basement apartment with about 80m² (861 sq ft).
I have to admit, it’s not easy. Initially, I was leaning towards an air-to-water heat pump, then we considered pellets for a while, and now we are back to the air-to-water heat pump. Meanwhile, I’ve also read about trench collectors, which, if installed by yourself, can save the high investment costs of geothermal systems and make them similarly priced to air-to-water heat pumps.
You often read that air-to-water heat pumps only work well if everything is properly sized and the winter is relatively mild. I would be interested in hearing generally if you would choose an air-to-water heat pump again and what your monthly electricity consumption is. I’m concerned about heating with electricity. In the past, night storage heaters were criticized, and now we are supposed to heat with electricity again? Even though the air-to-water heat pump is much more efficient, I still feel uneasy because of the dependency on electricity prices and all the horror stories about very high energy bills.
By the way, we were recommended the Wolf BWL-1-A (outdoor installation). It is supposed to be very, very quiet but not exactly small. Does anyone have experience with it?
What would you choose as an alternative to the air-to-water heat pump? Gas? That’s basically not an option for me. I’m not comfortable having a gas line in the house, unless you have good arguments for it.
Other alternatives? Fireplace with buffer tank? Pellets?
Looking forward to your answers.
Always make sure to gather information!!! This is a sensitive topic... Someone tried to sell us a 4 kW borehole for a 6 kW heating system. Contact the national geological agency (or equivalent) – they have detailed maps of soil conditions and heat extraction capacities, etc. Also, educate yourself about underfloor heating and related topics.
xycrazy schrieb:
f-pNo, could you share the size of your house and which heating system you installed? May I ask what the total cost for the geothermal system was? Our house has a total area of 172 sqm (1850 sq ft), including the utility room and storage room.
We installed a Vaillant Geotherm Plus VWS 82/3 with two boreholes providing a capacity of 7.8 kW.
The all-inclusive cost for the drilling—which covers the filling with brine concentrate and so on—was 7,126 euros. The company we hired is very reputable in our area, based in the Eifel region, and as far as I know, they operate within a radius of about 150 km (93 miles).
I can’t specify the exact cost for the Vaillant system itself, as it was included in the overall house price (the drilling had to be paid separately).
During our consultation, our general contractor estimated that the total cost for the ground source heat setup, including drilling, would be between 12,000 and 14,000 euros.
The comment by @Saruss is correct:
We built to KfW 70 standard (according to the 2009 Energy Saving Ordinance). For this, we used 36.5 cm (14 inches) Ytong blocks for the ground floor and 30 cm (12 inches) Ytong blocks for the upper floor.
One small note, which I’m not sure is usual or directly related to the heating system itself:
Up until moving in—including the heating phase to dry the screed—we consumed about 1,300 kWh of heating electricity. This amounted to approximately 275 euros during the construction phase. I mention this because two colleagues of mine said they spent well over 1,000 euros just on electricity for drying the screed.
[/QUOTE]
We used 2300 kWh for drying the screed, but the heating was done directly with electricity. So it has little to do with geothermal energy. My house is built to KfW 70 standards according to the 2009 Energy Saving Ordinance, but with a Tecalor 6.8 kW heat pump.
What does "drill holes for 7.8 kW" mean? There are so many variables: probe length, probe type, filling material (many still use one with poor thermal conductivity as packing), ground conditions, and different calculation models. Some standard calculations often assume too few operating hours, for example. For the drilling, not only the maximum power but also the amount of energy extracted over the year is important.
In our case, the brine return temperature in winter did not drop below about 5°C (41°F). It also matters how well the heating system is adjusted. Fine-tuning the heating curve and hysteresis helped me; this way I can currently maintain the temperature in the house perfectly without individual room controls.
What does "drill holes for 7.8 kW" mean? There are so many variables: probe length, probe type, filling material (many still use one with poor thermal conductivity as packing), ground conditions, and different calculation models. Some standard calculations often assume too few operating hours, for example. For the drilling, not only the maximum power but also the amount of energy extracted over the year is important.
In our case, the brine return temperature in winter did not drop below about 5°C (41°F). It also matters how well the heating system is adjusted. Fine-tuning the heating curve and hysteresis helped me; this way I can currently maintain the temperature in the house perfectly without individual room controls.
Saruss schrieb:
We had 2300 kWh for the screed drying, but it was heated directly with electricity. So it had little to do with geothermal energy. I also have a KfW70 house according to the 2009 Energy Saving Ordinance. However, with a Tecalor 6.8 kW heat pump.
What does “boreholes for 7.8 kW” mean? There are so many differences: probe length, probe type, grout (many still use materials with poor thermal conductivity as pressing material), soil, etc. And there are different calculation models. Some standard calculations, for example, often assume too few operating hours. For the drilling, not only the maximum output but also the amount of energy extracted over the year is important.
In our case, the brine temperature on the return side in winter did not drop below about 5°C (41°F). It also matters how well the heating system is adjusted. For me, fine-tuning the heating curve and hysteresis helped; so currently, without individual room controls, I can maintain the temperature in the house precisely.That’s true—now that you mention it, I remember it too. Our screed heating phase was also done using electricity only. Our general contractor once told us (because we initially thought geothermal was used for this) that heating the screed with geothermal energy could potentially cause the borehole to cool down.
The specification “boreholes for 7.8 kW” I took from the invoice. I don’t recall the exact depth—only that a double borehole was drilled. I think 120 m (about 394 feet) was mentioned once—it’s possible that this was the combined depth of both boreholes or the depth of each individually. It was quite a while ago—the drilling was done about one year ago. Damn age—the memory is fading.
The boreholes were filled with 95 liters (25 gallons) of brine concentrate.
Regarding the other points, I can’t say much—I’m still quite a layperson and am not very familiar yet a) with the Vaillant heat pump and b) with the various adjustment options and analyses. What I mean is that there may even be optimization potential in our system.
I hope the brine concentrate is inside the pipes. The boreholes are sealed with a material similar to cement (but a special compound made specifically for this purpose) to ensure the best possible surface contact with the pipes, enabling efficient heat transfer. There are significant differences in price and thermal conductivity here (unfortunately, better quality usually means higher cost).
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