ᐅ Heating System Question for New Build KfW 70: Air Source Heat Pump + Solar, Ice Storage?
Created on: 24 Feb 2015 11:42
H
hiasl86
Hello dear forum users!
We are currently planning a new build in southern Bavaria near the border with Salzburg. At the moment, we are looking for the right heating system for our home. We have a living area of about 140 sqm (1507 sq ft). We plan to build to KfW 70 standard (36 cm (14 inch) bricks with perlite filling).
What we definitely do not want is oil heating. Gas is also not an option for us since there is no connection available, and I do not want to have a gas tank buried in the garden. We also don’t really want a pellet heating system because of the required storage space.
We are actually leaning towards a heat pump. We initially wanted geothermal energy with a deep borehole (ground collectors are not feasible due to limited land area). We received an offer for the deep drilling, but to me, it seems very expensive (12,000 - 15,000 Euro). The problem is that the water management authority limits the drilling depth to 10 m (33 ft). This is partly because sulfate rock was found nearby at depths of 30–40 m (98–131 ft), and no drilling has been done directly in our neighborhood yet. The drilling company suggested drilling 9 times to 10 m (33 ft) as a safe option. The less certain option (1. due to permits and 2. because it is unclear how far you can actually drill) would be 4 times 23 m (75 ft).
Now we might consider switching to an air-to-water heat pump with solar support (for domestic hot water and heating assistance). What do you think about this combination? How effective is it and what about electricity consumption? How well do air-to-water heat pumps perform in winter on very cold days? What investment costs should we expect roughly?
We also came across the solar heat pump system, combining solar, air, heat pump, and ice storage. Has anyone had experience with such a system? How does it perform in winter? Is it possible that you might end up heating only with electricity if the ice storage freezes too early and cannot thaw quickly enough, or is the solar and air energy usually sufficient? What about investment costs—how much higher are they compared to the solar plus air-to-water heat pump version?
I have browsed quite a few forums looking for answers and experiences with ice storage. Opinions seem quite divided (too early freezing, not cost-effective due to high investment costs).
Thank you in advance for your help and advice!
Best regards
Matthias
We are currently planning a new build in southern Bavaria near the border with Salzburg. At the moment, we are looking for the right heating system for our home. We have a living area of about 140 sqm (1507 sq ft). We plan to build to KfW 70 standard (36 cm (14 inch) bricks with perlite filling).
What we definitely do not want is oil heating. Gas is also not an option for us since there is no connection available, and I do not want to have a gas tank buried in the garden. We also don’t really want a pellet heating system because of the required storage space.
We are actually leaning towards a heat pump. We initially wanted geothermal energy with a deep borehole (ground collectors are not feasible due to limited land area). We received an offer for the deep drilling, but to me, it seems very expensive (12,000 - 15,000 Euro). The problem is that the water management authority limits the drilling depth to 10 m (33 ft). This is partly because sulfate rock was found nearby at depths of 30–40 m (98–131 ft), and no drilling has been done directly in our neighborhood yet. The drilling company suggested drilling 9 times to 10 m (33 ft) as a safe option. The less certain option (1. due to permits and 2. because it is unclear how far you can actually drill) would be 4 times 23 m (75 ft).
Now we might consider switching to an air-to-water heat pump with solar support (for domestic hot water and heating assistance). What do you think about this combination? How effective is it and what about electricity consumption? How well do air-to-water heat pumps perform in winter on very cold days? What investment costs should we expect roughly?
We also came across the solar heat pump system, combining solar, air, heat pump, and ice storage. Has anyone had experience with such a system? How does it perform in winter? Is it possible that you might end up heating only with electricity if the ice storage freezes too early and cannot thaw quickly enough, or is the solar and air energy usually sufficient? What about investment costs—how much higher are they compared to the solar plus air-to-water heat pump version?
I have browsed quite a few forums looking for answers and experiences with ice storage. Opinions seem quite divided (too early freezing, not cost-effective due to high investment costs).
Thank you in advance for your help and advice!
Best regards
Matthias
hiasl86 schrieb:
Thanks for the answers.
How does it work with domestic hot water? Since heat pumps are best suited for small temperature differences, doesn’t heating water to 60°C (140°F) in winter require a lot of electricity?
What about combining an air-to-water heat pump with photovoltaics? That probably doesn’t pay off either, right?With "heat pump users," you will hardly find anyone in single-family homes producing hot water at 60°C (140°F) – it’s usually around 45–50°C (113–122°F). Of course, there should be sufficient flow to ensure the storage tank refills regularly (important regarding Legionella).
The situation is similar with photovoltaics. High self-consumption in practice is not possible without battery storage – and solar output is low in winter. For a third-party financed photovoltaic system including interest, insurance, repairs, reserves, etc., it is definitely no longer economically worthwhile.
See also: https://www.hausbau-forum.de/threads/lwwp-mit-Solarthermie-und-Kamin-kosten-nutzen-Sinn.11621/page-3
Häuslebau3r24 Feb 2015 13:26If I’m not mistaken, only heat pumps designed for older buildings provide 60 degrees Celsius (140 degrees Fahrenheit) to heat traditional radiators to the required temperature, right? For regular underfloor heating, as mentioned, the water temperature should be around 40-50 degrees Celsius (104-122 degrees Fahrenheit). That’s what I’ve understood so far.
From what I understand, an air-to-water heat pump alone would be sufficient for underfloor heating and domestic hot water and would be the most economical option without any combination, correct?
There are two types available here: the compact version and the split unit. Which one is recommended in terms of noise levels and efficiency?
Is it advisable to also install a ventilation system with heat recovery?
Thank you very much for your help!
There are two types available here: the compact version and the split unit. Which one is recommended in terms of noise levels and efficiency?
Is it advisable to also install a ventilation system with heat recovery?
Thank you very much for your help!
There are already many posts about controlled residential ventilation WITH heat recovery. Just make an effort and search through the forums. The general consensus is something like: not absolutely necessary (but who really ventilates properly manually), probably never economically worthwhile – but a tremendous gain in comfort.
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