ᐅ Air-to-water heat pump combined with solar thermal and a wood-burning stove: costs, benefits, and practicality
Created on: 1 Feb 2015 15:57
M
M.Mustermann
Hello everyone,
Here are a few key points upfront:
We plan to build a single-family house with 121sqm (1300 sq ft) of living space this summer. Ground floor and upper floor, for 2 adults and 2 children.
The roof will face south.
We will use Ytong (30cm (12 inches)) blocks, with triple-glazed windows. Underfloor heating will be installed.
We live in Hesse, Rhine-Main area.
A air-to-water heat pump will be installed since we do not have gas and do not want to have any tanks for gas, oil, or pellets either inside the house or buried in the garden.
We would also like a fireplace for coziness and because we have almost free access to firewood. Solar thermal is also being considered; the question is whether it is worthwhile and if it should be used just for hot water or also for heating.
The following offer has already been presented to us:
A Nibe air-to-water heat pump split system with building heat load up to 7 kW, a buffer storage tank of 270l (71 gallons) with an additional 100l (26 gallons) buffer tank including Pedotherm underfloor heating.
For solar, 4sqm (43 sq ft) – 2 collectors and a 230l (61 gallons) buffer tank would be added.
The extra cost for solar is about 4000,- €.
For connecting a hydronic fireplace, including piping, pump, return lifting, and drainage protection, nearly 3000,- € is charged.
I am calculating about 3500,- € for a fireplace with an external chimney.
So, including the air-to-water heat pump, it would be over 10,000,- € for the fireplace and solar combined.
Regarding the questions:
The buffer storage tank seems very small for this project—is that accurate?
What makes sense for the heating system, considering it should pay off as much as possible? Because of the fireplace desire, it might not be possible, but well, the fireplace is a luxury and would be accepted even if it is not cost-effective.
I am concerned about only having an air-to-water heat pump in the cold season, due to electricity costs, and 7 kW building heat load seems low (though I have no expertise). A friend has an air-to-air heat pump and currently the electricity costs are extremely high.
What makes sense? What else should I include in the calculation, what might I have overlooked or should consider?
What do you think about Nibe?
Regards,
Max
Here are a few key points upfront:
We plan to build a single-family house with 121sqm (1300 sq ft) of living space this summer. Ground floor and upper floor, for 2 adults and 2 children.
The roof will face south.
We will use Ytong (30cm (12 inches)) blocks, with triple-glazed windows. Underfloor heating will be installed.
We live in Hesse, Rhine-Main area.
A air-to-water heat pump will be installed since we do not have gas and do not want to have any tanks for gas, oil, or pellets either inside the house or buried in the garden.
We would also like a fireplace for coziness and because we have almost free access to firewood. Solar thermal is also being considered; the question is whether it is worthwhile and if it should be used just for hot water or also for heating.
The following offer has already been presented to us:
A Nibe air-to-water heat pump split system with building heat load up to 7 kW, a buffer storage tank of 270l (71 gallons) with an additional 100l (26 gallons) buffer tank including Pedotherm underfloor heating.
For solar, 4sqm (43 sq ft) – 2 collectors and a 230l (61 gallons) buffer tank would be added.
The extra cost for solar is about 4000,- €.
For connecting a hydronic fireplace, including piping, pump, return lifting, and drainage protection, nearly 3000,- € is charged.
I am calculating about 3500,- € for a fireplace with an external chimney.
So, including the air-to-water heat pump, it would be over 10,000,- € for the fireplace and solar combined.
Regarding the questions:
The buffer storage tank seems very small for this project—is that accurate?
What makes sense for the heating system, considering it should pay off as much as possible? Because of the fireplace desire, it might not be possible, but well, the fireplace is a luxury and would be accepted even if it is not cost-effective.
I am concerned about only having an air-to-water heat pump in the cold season, due to electricity costs, and 7 kW building heat load seems low (though I have no expertise). A friend has an air-to-air heat pump and currently the electricity costs are extremely high.
What makes sense? What else should I include in the calculation, what might I have overlooked or should consider?
What do you think about Nibe?
Regards,
Max
Heimat2015 schrieb:
@hauslebau3r....
Thank you for your contribution... I’m starting to agree with your view on photovoltaics...
Does it all work automatically? In other words, as soon as enough energy comes from the roof, do I use it myself? If not, do I have to buy electricity?
Then I would need to heat everything well during the day, so a buffer storage tank might make sense again.
Oh man, it’s not that simple...
As for the ventilation system, I agree with you there too, but we have two small children, so there will always be activity in the house. When no one is home, then it’s something to think about.
Still, I’m cautious about this topic because if you have such a system, you really have to pay attention to maintenance and not just change a “little filter” now and then. But that’s not the topic here.
That’s why I’m building without additional insulation, and I think with the Poroton brick we are doing pretty well...Are you following this? Photovoltaics are very questionable in terms of economic profitability. And the bank’s calculation (when financing is involved) looks very different from the solar installer’s.
How do you plan to heat the buffer during the day in winter when there’s no sun?
A buffer tank with a heat pump always reduces efficiency if it is used exclusively to supply underfloor heating.
Central mechanical ventilation with heat recovery: what else should you maintain besides changing “little filters”? According to the manufacturer’s service team at startup, you just have to clean the heat exchanger once a year and check the siphon occasionally—that’s it. And if there’s a fault in the system, you’ll see it in the error message.
Heimat2015 schrieb:
That is the keyword "regularly"—70% of ventilation system owners won’t do that, and then it will quickly become unpleasant when dirt spreads throughout the home.Well, I believe the reality is more likely the opposite… at least in one’s own house…
Heimat201518 Feb 2015 09:20I can just as well turn this around. If the sun isn’t shining in winter, the solar thermal system won’t deliver anything from the roof... please understand me correctly... I’m fully aware of the buffer tank situation; I’m simply looking for a cost-effective upgrade solution for the air-to-water heat pump! If I’m going to spend, say, 10,000 euros extra, I want to get the maximum benefit out of it in the end and have the air-to-water heat pump supported during “bad” (cold) times.
I won’t say anything more about ventilation now. Everyone can see it as they wish. I have formed my own opinion on that.
I won’t say anything more about ventilation now. Everyone can see it as they wish. I have formed my own opinion on that.
Mycraft schrieb:
Well, I actually believe the opposite is true... at least when it comes to one’s own home...Exactly – I also take good care of my car accordingly...
Heimat2015 schrieb:
I can turn that around just as easily. When the sun doesn’t shine in winter, nothing comes from the roof with solar thermal either... please understand me correctly... I’m aware of the buffer tank issue, I’m just looking for a "cost-effective upgrade solution" for the air-to-water heat pump!!! If I were to invest, say, an additional 10,000 euros, I want to get the maximum benefit from it in the end and have the air-to-water heat pump supported during "difficult" (cold) periods.
I won’t comment on the ventilation anymore. Everyone can see it their own way. I’ve formed my opinion on that.How large is the house, which climate zone is it in, how many occupants, and what is the energy efficiency standard or building code (energy-saving ordinance/planning permission)?
What does the heating load calculation say? Only if this is available can you start considering options.
EveundGerd18 Feb 2015 11:32I agree. Especially since there will be a consultation on this.
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