ᐅ Gas with solar thermal? Or heat pump with photovoltaic? Advice needed
Created on: 5 Feb 2020 08:57
M
Micha8589
Good morning to the forum,
I have been researching heating options for quite some time and have gathered a few opinions, which have only made me more uncertain about my decision. That’s why I thought I’d ask the forum.
My family (2 adults, 1 child) is planning to build the following single-family house at the end of this year or beginning of next year:
Single-family home with pitched roof
Approximately 115 m² (1,237 sq ft)
Solid construction (calcium silicate brick ground and upper floors, brick-clad)
No KFW standard
Building location: southern Mecklenburg
Unfortunately, I can’t provide an energy performance certificate or heating load calculation yet, as the preliminary offer is still being prepared. I am also aware that a general statement can’t really be made since every house and heating behavior is individual.
The construction company advised us to install a modern hybrid heating system consisting of a gas condensing boiler and two solar thermal panels on the roof for domestic hot water, as the initial costs are relatively low (plus installation of the central gas connection), and this technology has proven reliable. The entire house is planned to have underfloor heating. According to the company, they have had very positive experiences with this and consider the technology future-proof. (There is also the idea of a fireplace in the living room.)
On the other hand, I think gas prices will not get any cheaper in the future, and the topic of CO₂ taxes (especially concerning the fireplace) worries me somewhat.
In theory, I would prefer to install a geothermal heat pump combined with a suitable photovoltaic system because this would make me independent of fossil fuels and allow me to heat “off-grid” to a certain extent, depending on efficiency. However, I am hesitant because of the very high initial costs and don’t really know how these compare to operational costs. I also can no longer realistically assess which technology offers the best cost-performance ratio (except for air-source heat pumps).
As you can see, I am completely undecided and hope to get some feedback and expertise from the forum.
Thanks in advance for your replies.
I have been researching heating options for quite some time and have gathered a few opinions, which have only made me more uncertain about my decision. That’s why I thought I’d ask the forum.
My family (2 adults, 1 child) is planning to build the following single-family house at the end of this year or beginning of next year:
Single-family home with pitched roof
Approximately 115 m² (1,237 sq ft)
Solid construction (calcium silicate brick ground and upper floors, brick-clad)
No KFW standard
Building location: southern Mecklenburg
Unfortunately, I can’t provide an energy performance certificate or heating load calculation yet, as the preliminary offer is still being prepared. I am also aware that a general statement can’t really be made since every house and heating behavior is individual.
The construction company advised us to install a modern hybrid heating system consisting of a gas condensing boiler and two solar thermal panels on the roof for domestic hot water, as the initial costs are relatively low (plus installation of the central gas connection), and this technology has proven reliable. The entire house is planned to have underfloor heating. According to the company, they have had very positive experiences with this and consider the technology future-proof. (There is also the idea of a fireplace in the living room.)
On the other hand, I think gas prices will not get any cheaper in the future, and the topic of CO₂ taxes (especially concerning the fireplace) worries me somewhat.
In theory, I would prefer to install a geothermal heat pump combined with a suitable photovoltaic system because this would make me independent of fossil fuels and allow me to heat “off-grid” to a certain extent, depending on efficiency. However, I am hesitant because of the very high initial costs and don’t really know how these compare to operational costs. I also can no longer realistically assess which technology offers the best cost-performance ratio (except for air-source heat pumps).
As you can see, I am completely undecided and hope to get some feedback and expertise from the forum.
Thanks in advance for your replies.
hegi___ schrieb:
20 per month = nearly €5000 in 20 years
Gas connection cost €2000 one-time
Fireplace cost €2500 one-time
Chimney sweep €100 per year = €2000 in 20 years.
Gas will inevitably become more expensive due to the CO2 tax.
With photovoltaic systems, I can install a battery later if electricity becomes too expensive. With gas, that is more difficult...
Batteries are becoming increasingly affordable... Batteries are becoming more affordable, but they will never be free. Therefore, this calculation can be applied reasonably to both gas and photovoltaic systems...
T
T_im_Norden8 Feb 2020 19:27The chimney sweep is required every 3 years.
A condensing boiler does not need a chimney, only a flue pipe.
Gas connection costs 2000 euros, whereas a geothermal probe costs at least 10,000 euros, which still results in 3,000 euros or more of additional costs for gas.
You can look at and calculate this from different perspectives.
A condensing boiler does not need a chimney, only a flue pipe.
Gas connection costs 2000 euros, whereas a geothermal probe costs at least 10,000 euros, which still results in 3,000 euros or more of additional costs for gas.
You can look at and calculate this from different perspectives.
Chimney sweeping costs 90 every two years, which is less than 50 per year. Connection here is 750. Which chimney? There is a pipe going up from the boiler. That’s it. And something that is often overlooked: the air-to-water heat pump (AWHP) is technically much more complex than the gas boiler and therefore requires more maintenance and is more prone to faults. This results in technician costs. Also, the lifespan of the pump, according to current technology, is around 10 years. This means a significant investment will be necessary then.
Conclusion: There will always be people who are tech-savvy and want what is new or interesting and try to justify it financially. Purely economically, however, you usually do better with something simple, rugged, and reliable. Owners of high-complexity cars know this, which is why, for example, company fleets tend to choose base models like the Astra or Focus rather than a Tesla or something similar. Karsten
Conclusion: There will always be people who are tech-savvy and want what is new or interesting and try to justify it financially. Purely economically, however, you usually do better with something simple, rugged, and reliable. Owners of high-complexity cars know this, which is why, for example, company fleets tend to choose base models like the Astra or Focus rather than a Tesla or something similar. Karsten
T_im_Norden schrieb:
Chimney sweep every 3 years.
A condensing boiler doesn’t need a chimney, only a flue pipe.
Gas connection costs 2000 euros versus geothermal probe ≥10,000 euros still means 3000 euros plus for gas.
You can look at it and calculate it from different perspectives. You don’t need the geothermal probe, but the connection is necessary, so the comparison isn’t really accurate. That’s actually the case for all options. It’s a very individual matter. In our northwest region, most houses are built by general contractors, while here in Nuremberg only about 10% of houses are owner-built. The rest were built by general contractors. The crucial factor is what the bottom line comes to. In our case, it was cheaper to build a KfW55-standard house with an air-to-water heat pump than to meet the standard Energy Saving Ordinance with gas, since the centralized controlled residential ventilation was a given for us and the KfW conditions in 2016 were significantly more favorable than a regular loan. For others, the situation is different; you can’t generalize.
Nordlys schrieb:
Chimney sweep every two years for €90, so less than €50 per year. Connection here €750. Which chimney? A pipe goes up from the boiler, that’s it. And something always gets overlooked: the air-to-water heat pump is technically more complex than a gas boiler and therefore requires more maintenance and is more prone to faults. That means technician costs. Also, the lifespan of the pump — based on current technology — is about 10 years. That means a substantial reinvestment is due then.
Conclusion: there will always be people who are tech-oriented and want what is new or interesting and justify the cost. But purely economically, you are generally better off with something simple, rugged, and reliable. Owners of complex cars know this; that’s why fleets typically prefer base models like the Astra or Focus rather than Teslas or such. Karsten Even though I usually appreciate your posts, much of this is incorrect here. An air-to-water heat pump is not particularly complicated. It’s basically an inverted refrigerator; if you look inside, you’ll be surprised how simple it is. And a refrigerator isn’t exactly high tech. You can do maintenance yourself, which costs nothing. The lifespan is comparable to a gas condensing boiler; I haven’t heard otherwise so far. These units can also run 20 to 30 years without major issues.
As for company fleets, that has much more to do with the bargain prices manufacturers offer in leasing deals. Leasing factors of 0.5 or 0.6 are not uncommon; recently, you could lease a Golf for under €100 per month privately. A BMW 5 Series was available for €249 per month at a model change. Tesla conditions, by contrast, are totally unattractive. The combustion engine with all its add-on parts and required emissions treatment is the really complex beast. See, for example, timing belt issues at VW, timing chain problems at BMW, and the EGR valves are basically expensive wear parts at many manufacturers, and so on. Compared to that, an electric motor with its components is quite simple — actually simple, rugged, and reliable.
ares83 schrieb:
You don’t necessarily need the geothermal probe, but you do need the connection, so the comparison is flawed. Actually, that applies to all options. It really depends on the individual case. In our region in the northwest, most houses are built by general contractors, while here in NBG only 10% of the houses are self-managed projects. The rest were built by general contractors. What matters is the bottom line. In our case, it was cheaper to build a KfW55 standard home with an air-to-water heat pump than to follow the standard energy saving regulation with gas heating, since centralized controlled residential ventilation was already planned for us and the 2016 KfW conditions were significantly more favorable than a regular loan. For others, the situation is different, so no generalizations can be made.
Although I usually appreciate your posts, much of this is incorrect. An air-to-water heat pump isn’t particularly complicated. It’s basically a reversed refrigerator; if you look inside, you’ll be surprised how simple these units are. And a refrigerator is far from high-tech. Maintenance can be done by yourself and costs nothing. The lifespan is comparable to that of a gas condensing boiler—I haven’t heard otherwise. These units often run 20 to 30 years without major issues.Do you have any sources for this incorrect claim? However, I do know that manufacturers design these systems for a maximum of 15 years, but more often these air heat pumps fail after 5 to 10 years. Gas condensing boilers can probably be operated for 30 years without major repairs.I don’t believe in heat pumps, although I have one myself. Which, by the way, has already had quite a few defects.
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