Hello everyone,
We currently live in a house (built in 2015, rented) with the following energy consumption values:
We have looked into solar options (both photovoltaic and thermal) to support or power an air-source heat pump, but financially it doesn’t seem to add up. Additionally, our house will have a gable roof aligned exactly north-south, meaning one roof side faces east and the other west.
We currently live in a house (built in 2015, rented) with the following energy consumption values:
- Household electricity: 3,000 kWh per year
- Air-source heat pump: 4,300 kWh electricity per year, heating output 13,000 kWh
- Solar thermal system: 1,000 kWh thermal energy
We have looked into solar options (both photovoltaic and thermal) to support or power an air-source heat pump, but financially it doesn’t seem to add up. Additionally, our house will have a gable roof aligned exactly north-south, meaning one roof side faces east and the other west.
- For the photovoltaic system, I initially considered a battery so we wouldn’t have to feed electricity into the grid for very little compensation and could instead use the generated power for the air-source heat pump. However, such a battery quickly costs upwards of 6,000 euros; for that price, you could pay for gas for 8 years. In other words, even if it were a perfect battery that supplied all the electricity for the heat pump at no cost, it would need to last at least 8 years. This doesn’t even take into account that the air-source heat pump itself is also more expensive than the gas heating system.
- I am skeptical about solar thermal because during the summer months, when the sun is strongest, you actually need the least hot water. Electricity, at least household electricity, is always needed.
- Is it possible to install a gas heating system if you only build according to the energy-saving regulations (e.g., EnEV / energy performance requirements) without installing anything on the roof? Or would that not comply with the maximum allowed primary energy demand?
- What about using only an air-source heat pump (like we have now in our rental)? Somehow it is so expensive that it never really pays off compared to gas, regardless of whether you have photovoltaic or solar thermal on the roof. Gas is just too cheap...
That’s true. Joe is right. You have to look at each case individually.
I find Zaba’s comment about a few thousand euros and the fuss around it annoying because it subtly implies that anyone who calculates carefully has no right to build. That’s the typical attitude of the Westerland man, thinking he’s among his own kind. Karsten
I find Zaba’s comment about a few thousand euros and the fuss around it annoying because it subtly implies that anyone who calculates carefully has no right to build. That’s the typical attitude of the Westerland man, thinking he’s among his own kind. Karsten
Nordlys schrieb:
That’s true. Joe is right. Each case needs to be looked at individually.
I find Zaba’s comment about a few thousand euros and the fuss around it quite frustrating because it implies, albeit subtly, that anyone who carefully calculates doesn’t have the right to build. That’s that typical “Westerland man” attitude of being insular. Karsten You are reading more into this than necessary.
How much are we actually talking about for the heating system purchase—2,000 to 3,000 euros (about $2,000 to $3,000) difference between gas and air-to-water heat pump? And over 20 years, I neither hear nor see a significant financial difference. Especially if photovoltaic systems are part of the plan; it might even be cheaper over 20 years and, in the best case, generate income after 15 years.
A gas heating system can be fully installed in the basement for about 5,000 euros (approximately 5,000 dollars). A heat pump starts at around 15,000 to 20,000 euros (about 15,000 to 20,000 dollars), depending heavily on the model. So, the difference is roughly 10,000 euros (10,000 dollars). Heat pumps are also more prone to issues compared to gas heating systems.
Nowadays, a gas heating chimney typically requires a 50mm (2-inch) pipe plus a 100mm (4-inch) pipe for fresh air, or a complete chimney system costing about 1,500 euros (1,500 dollars). From a cost perspective, gas heating still seems to have the advantage, especially since these systems can last about 30 years, which cannot be said for heat pump compressors. Additionally, at very low temperatures, electricity consumption for heat pumps is extremely high, so the current annual energy costs tend to favor gas over heat pumps. Furthermore, heat pumps have a higher initial purchase price, shorter lifespan, and require more frequent maintenance.
For gas systems, chimney sweep inspections and hearth examinations cost about 60 euros (60 dollars) per year, and 100 euros (100 dollars) every three years. On top of that, there is the annual boiler cleaning costing around 120 euros (120 dollars).
And no, I’m not a gas enthusiast and I do not own a gas heating system.
Nowadays, a gas heating chimney typically requires a 50mm (2-inch) pipe plus a 100mm (4-inch) pipe for fresh air, or a complete chimney system costing about 1,500 euros (1,500 dollars). From a cost perspective, gas heating still seems to have the advantage, especially since these systems can last about 30 years, which cannot be said for heat pump compressors. Additionally, at very low temperatures, electricity consumption for heat pumps is extremely high, so the current annual energy costs tend to favor gas over heat pumps. Furthermore, heat pumps have a higher initial purchase price, shorter lifespan, and require more frequent maintenance.
For gas systems, chimney sweep inspections and hearth examinations cost about 60 euros (60 dollars) per year, and 100 euros (100 dollars) every three years. On top of that, there is the annual boiler cleaning costing around 120 euros (120 dollars).
And no, I’m not a gas enthusiast and I do not own a gas heating system.
I see it differently. Many posts in various forums suggest a significantly shorter lifespan than 30 years. The indestructible cast iron boilers no longer exist. Incorrect settings cause boilers to fail quickly due to frequent cycling. One manufacturer even discontinued spare parts supply for their control system after ten years.
Heat pumps do not generally have a shorter lifespan. However, the installer must be highly knowledgeable, because otherwise the system breaks down quickly and energy consumption rises rapidly. Other than that, only prejudices caused by improper installation are listed here.
Only the price varies, as the general contractor charges whatever they want. This brings the individual situation back into consideration.
Heat pumps do not generally have a shorter lifespan. However, the installer must be highly knowledgeable, because otherwise the system breaks down quickly and energy consumption rises rapidly. Other than that, only prejudices caused by improper installation are listed here.
Only the price varies, as the general contractor charges whatever they want. This brings the individual situation back into consideration.
From experience, our detached house had a Vaillant boiler from 1999 to 2016, which the buyer then replaced, even though it wasn’t broken. I would have kept it running a little longer. These units last about 20 years. We didn’t have many repairs—maybe replacing some valve once, that was about it. But with a maintenance contract, it was serviced once a year. That usually cost around 120 euros. I’ve arranged a similar contract again now. That way, you are on the safe side. The chimney costs are really negligible; the chimney sweep comes every two years, and the chimney itself is just a pipe sticking out of the roof, maybe 1.50 meters (5 feet) long. Karsten
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