Hello everyone,
The planned construction start for our approximately 160m² (1,722 sq ft) bungalow is scheduled for early 2013. We are currently still in the planning phase. Now the question arises: which heating system should we choose? Can you recommend anything?
I would like to move away from oil or gas heating systems. Technically, I am already convinced of pellet heating, but I would prefer to be independent. What alternatives are left then? Heat pump?
Best regards, EarlGrey
The planned construction start for our approximately 160m² (1,722 sq ft) bungalow is scheduled for early 2013. We are currently still in the planning phase. Now the question arises: which heating system should we choose? Can you recommend anything?
I would like to move away from oil or gas heating systems. Technically, I am already convinced of pellet heating, but I would prefer to be independent. What alternatives are left then? Heat pump?
Best regards, EarlGrey
C
CharlieBrown14 Nov 2012 15:08It was just a question out of pure interest without any specific context.
Regards
Regards
M
Martin20629 Nov 2012 03:31I need to refer back a bit—I haven’t been around here for a few weeks.
Air source heat pumps can be problematic in many parts of Germany (south, east, low mountain ranges, etc.). Even though they can work well in KfW40-standard houses, the risk of excessively high operating costs is significant—especially since it’s not just about the device itself but also about good planning and installation, which are much harder to achieve than you might think.
If this isn’t done properly, the difference compared to gas heating (at today’s still valid gas prices) can quickly become quite small.
What’s so bad if a heating system only pays off compared to others after 10 years? Usually, people live in their own home for at least five decades or even longer. A heating system is expected to last 15-20 years, so if it has already proven cost-effective after 10 years, it has paid off. The question is also how significant the advantages will be in the following years once the additional investment is recovered.
__
> "In an uninsulated older building, a heating system with high fixed costs and low consumption (e.g., geothermal heat pump) would be the better alternative."
Definitely not! That’s a too simplistic view. Other factors come into play here—such as the fact that heat pumps generally have a significantly poorer efficiency when high flow temperatures are required, as is usually the case in older buildings. Heat pumps respond quite differently to environmental conditions than gas, oil, pellets, and similar systems. (If we had used a pellet heating system instead of geothermal as an example here, it would look different.) See also the article from €uro dated 29.9.12.
What is suitable depends on the heating load and the heat demand calculations—and of course on individual consumer behavior.
You can calculate the heating load yourself—at least accurately enough for selecting the type of heating system. (No, I won’t provide a link. Simply search for something like “how to calculate heating load” and you’ll find relevant information.)
A predominantly solar thermal heat supply for the house is certainly great. But it is the most expensive option, because 1) you need a very large solar thermal system (around 50 m² (540 sq ft) of solar collectors plus at least a 5,000-liter (1,320-gallon) special storage tank) and 2) a second heat generator for the "low-sun" weeks and months.
Photovoltaic systems only provide independence if you include a battery storage... which, in a practical size, alone costs 10,000€ and more.
Basically, if the house is suitable, I would recommend geothermal combined with controlled mechanical ventilation with heat recovery. For a KfW55 standard house or better. It depends on the available investment budget today and how you estimate future energy costs.
In this case, leave solar thermal out—not because its efficiency is poor, but because geothermal provides heat so cheaply that the additional investment in solar thermal can no longer be justified.
Also, fundamentally: use as much as necessary, but as little as possible.
So, no exclusive frills with the heating system, but rather a compact brine heat pump unit (heat pump, pumps, domestic hot water preparation/storage, control—all in one cabinet-like device about 60 x 70 x 200 cm (24 x 28 x 79 inches)) and a well- or individually-dimensioned underfloor heating system. Ideally, a concept that works without individual room thermostats, so it “self-regulates.”
Heating with wood or pellets is gradually becoming too expensive, unless you have your own wood and the time and means to do it yourself.
I don’t think the idea of solar thermal combined with a heat pump or log wood boiler is good—I’ve already explained the general reasons why.
And above all, don’t believe anything that doesn’t make sense to you—for example, achieving up to 23°C (73°F) indoor temperature with 26°C (79°F) flow temperature in wall heating—that may work where temperatures don’t drop below +10°C (50°F) (southern Italy, Africa... places where Energiefuxx probably operates), but not in large parts of Germany.
Wall heating in new buildings also has a frequently underestimated problem:
Large areas are usually taken up by windows—you want light and sun. That leaves fewer walls for the wall heating system. Even if there are enough walls left, you should know that these “radiant walls” must not be shaded by wardrobes, large pictures, etc.—otherwise, the principle won’t work anymore. By the way, with wall heating, you also have to forgo warm floors.
So, that’s it for now.
Regards
-Martin-
Air source heat pumps can be problematic in many parts of Germany (south, east, low mountain ranges, etc.). Even though they can work well in KfW40-standard houses, the risk of excessively high operating costs is significant—especially since it’s not just about the device itself but also about good planning and installation, which are much harder to achieve than you might think.
If this isn’t done properly, the difference compared to gas heating (at today’s still valid gas prices) can quickly become quite small.
What’s so bad if a heating system only pays off compared to others after 10 years? Usually, people live in their own home for at least five decades or even longer. A heating system is expected to last 15-20 years, so if it has already proven cost-effective after 10 years, it has paid off. The question is also how significant the advantages will be in the following years once the additional investment is recovered.
__
> "In an uninsulated older building, a heating system with high fixed costs and low consumption (e.g., geothermal heat pump) would be the better alternative."
Definitely not! That’s a too simplistic view. Other factors come into play here—such as the fact that heat pumps generally have a significantly poorer efficiency when high flow temperatures are required, as is usually the case in older buildings. Heat pumps respond quite differently to environmental conditions than gas, oil, pellets, and similar systems. (If we had used a pellet heating system instead of geothermal as an example here, it would look different.) See also the article from €uro dated 29.9.12.
What is suitable depends on the heating load and the heat demand calculations—and of course on individual consumer behavior.
You can calculate the heating load yourself—at least accurately enough for selecting the type of heating system. (No, I won’t provide a link. Simply search for something like “how to calculate heating load” and you’ll find relevant information.)
A predominantly solar thermal heat supply for the house is certainly great. But it is the most expensive option, because 1) you need a very large solar thermal system (around 50 m² (540 sq ft) of solar collectors plus at least a 5,000-liter (1,320-gallon) special storage tank) and 2) a second heat generator for the "low-sun" weeks and months.
Photovoltaic systems only provide independence if you include a battery storage... which, in a practical size, alone costs 10,000€ and more.
Basically, if the house is suitable, I would recommend geothermal combined with controlled mechanical ventilation with heat recovery. For a KfW55 standard house or better. It depends on the available investment budget today and how you estimate future energy costs.
In this case, leave solar thermal out—not because its efficiency is poor, but because geothermal provides heat so cheaply that the additional investment in solar thermal can no longer be justified.
Also, fundamentally: use as much as necessary, but as little as possible.
So, no exclusive frills with the heating system, but rather a compact brine heat pump unit (heat pump, pumps, domestic hot water preparation/storage, control—all in one cabinet-like device about 60 x 70 x 200 cm (24 x 28 x 79 inches)) and a well- or individually-dimensioned underfloor heating system. Ideally, a concept that works without individual room thermostats, so it “self-regulates.”
Heating with wood or pellets is gradually becoming too expensive, unless you have your own wood and the time and means to do it yourself.
I don’t think the idea of solar thermal combined with a heat pump or log wood boiler is good—I’ve already explained the general reasons why.
And above all, don’t believe anything that doesn’t make sense to you—for example, achieving up to 23°C (73°F) indoor temperature with 26°C (79°F) flow temperature in wall heating—that may work where temperatures don’t drop below +10°C (50°F) (southern Italy, Africa... places where Energiefuxx probably operates), but not in large parts of Germany.
Wall heating in new buildings also has a frequently underestimated problem:
Large areas are usually taken up by windows—you want light and sun. That leaves fewer walls for the wall heating system. Even if there are enough walls left, you should know that these “radiant walls” must not be shaded by wardrobes, large pictures, etc.—otherwise, the principle won’t work anymore. By the way, with wall heating, you also have to forgo warm floors.
So, that’s it for now.
Regards
-Martin-
Martin206 schrieb:
....Air-source heat pumps are not unproblematic in many parts of Germany (south, east, mid-mountain regions, etc.). I am not aware of any system that is generally or unconditionally "unproblematic"!Martin206 schrieb:
... mainly because it’s not just about the device itself, but also about good planning and installation ... which are much harder to achieve than one might think. Accurate sizing and planning are essential for every system, even for a supposedly straightforward gas condensing boiler with radiators. Significant errors are made even with the latter.The upper curve in each case reflects what I have observed in actual installations. By the way, good planning and sizing are quite easy and affordable to obtain.
Martin206 schrieb:
... You can also calculate the heating load yourself at least as accurately as needed for selecting the heating method. ...Just google something like "how to calculate heating load," and you will find something.)... Hardly, once estimated => it remains guesswork! Without room heating loads, a comprehensive assessment is hardly possible or meaningful. The standardized heating load is essentially a "byproduct" in this process. Therefore, any preliminary estimate can be omitted.Martin206 schrieb:
... Photovoltaics only provide independence, .... It is not necessarily required to be fully independent; it is sufficient if a photovoltaic system produces as many kWh over the year as are needed for heating, hot water, ventilation, and possibly household consumption.Martin206 schrieb:
... Also basically: As much as necessary – but as little as possible. Correct!Martin206 schrieb:
... Wall heating in new buildings also has a mostly overlooked problem today:... Energetically speaking, worse at exterior walls than underfloor heating, unless improved insulation is applied. On the other hand, it is significantly less sluggish!Martin206 schrieb:
..., that you must not simply "block" these radiant walls with cabinets, large pictures, etc., otherwise the principle won’t work anymore. The same applies for underfloor heating => inactive or covered heating surfaces. This must be taken into account during system design. Additionally, the choice of floor covering has a significant impact. Thick rugs or parquet flooring can noticeably reduce energy efficiency.Comparable to a towel radiator in the bathroom that is covered accordingly. If this is included in the energy balance, achieving set temperatures will likely be difficult. Usually, only raising the flow temperature and/or flow rate helps. A weekend, especially when using a heat pump, is not pleased by this at all.
Martin206 schrieb:
... By the way, with wall heating, you also have to give up warm floors ( With the suitable operating temperatures commonly used for air-source heat pumps as heat generators, "warm feet" are hardly a relevant criterion anymore.v.g.
E
Energiefuxx29 Nov 2012 15:34In general, I would always recommend including solar energy. However, this needs to be considered carefully. The most efficient and simplest system is the drain-back solar system with non-pressurized storage tanks, combined with wall heating. The design of the wall heating typically covers about 50% of the floor area since not all walls are fully covered by furniture.
The drain-back system should be supported by a heat pump or pellet boiler. A large storage tank is essential to store all the generated heat.
The common problem is that many heating engineers or planners are not familiar with these systems and are resistant to learning. This is not meant as criticism but reflects a broader societal issue, also seen with other consumer goods. Customers are often expected not to think critically but to follow the industry’s marketing and advertising, which distort relevant standards, regulations, and technical formulas that neither the sellers nor the customers fully understand—and have been designed solely for that purpose.
The real question should be: How must a solar system be constructed to meet the customer’s needs, and why does it have to be installed as a pressurized system?
1. Durable, long-lasting, and reliable operation
This can only be achieved if:
a) there is no overheating or stagnation in the collectors, as these cause most damages
b) the system is protected against freezing—same issue as above
c) the system is free of scale buildup, which can reduce efficiency by up to 50%
d) corrosion is prevented—on average, storage tanks must be replaced every 10 years or are so corroded inside that an adequate performance is no longer possible
2. Avoid unnecessary and maintenance-prone components
A solar system is not a conventional heating system and does not need to be designed as a pressurized system. In self-draining drain-back systems with non-pressurized storage tanks, materials that initially add cost and typically need replacement after overheating, freezing, or a few years can be omitted. The following components are not needed in drain-back systems with non-pressurized tanks:
- Expansion vessels
- Flow regulators
- Safety valves
- Automatic air vents
- Glycol-based heat transfer fluids (proper drain-back systems are operated with regular water)
- Filling valves
- Sacrificial anodes
These components usually add €700-1000 to the installation cost, causing the customer to accept future maintenance issues as these parts have to be replaced at intervals of 5 to 10 years at least.
Going even further, when combining steel storage tanks with underfloor heating, separation stations are required, costing another €1000-2000. These separation stations are necessary because underfloor heating pipes made of polypropylene are not oxygen-tight and would otherwise allow oxygen to enter the steel storage tank, causing immediate corrosion and sludge buildup. Using non-pressurized storage tanks made of polypropylene, which is the same material as the underfloor heating pipes, allows direct connection without separation stations. This prevents rust and sludge formation in both the underfloor heating and the storage tank, often for 40 years or more.
Since most heating engineers are experienced with steel tanks and there are only very few manufacturers producing these robust, temperature-resistant, and structurally solid layered storage tanks (without fragile inner liners), it will take some time for this approach to become widely accepted among "experts." End customers, after extensive consultations and trade show visits, often come to realize this on their own and opt for a rational construction with a drain-back system and non-pressurized storage tank, which genuinely saves them money, energy, maintenance, and trouble.
When combined with an efficient surface heating system, customers usually find themselves more than satisfied.
It is also possible on a large scale—as demonstrated by a system with a 130,000-liter (34,340-gallon) stratified storage tank and 200 heat recovery ventilators (HRVs) in Germany.
The drain-back system should be supported by a heat pump or pellet boiler. A large storage tank is essential to store all the generated heat.
The common problem is that many heating engineers or planners are not familiar with these systems and are resistant to learning. This is not meant as criticism but reflects a broader societal issue, also seen with other consumer goods. Customers are often expected not to think critically but to follow the industry’s marketing and advertising, which distort relevant standards, regulations, and technical formulas that neither the sellers nor the customers fully understand—and have been designed solely for that purpose.
The real question should be: How must a solar system be constructed to meet the customer’s needs, and why does it have to be installed as a pressurized system?
1. Durable, long-lasting, and reliable operation
This can only be achieved if:
a) there is no overheating or stagnation in the collectors, as these cause most damages
b) the system is protected against freezing—same issue as above
c) the system is free of scale buildup, which can reduce efficiency by up to 50%
d) corrosion is prevented—on average, storage tanks must be replaced every 10 years or are so corroded inside that an adequate performance is no longer possible
2. Avoid unnecessary and maintenance-prone components
A solar system is not a conventional heating system and does not need to be designed as a pressurized system. In self-draining drain-back systems with non-pressurized storage tanks, materials that initially add cost and typically need replacement after overheating, freezing, or a few years can be omitted. The following components are not needed in drain-back systems with non-pressurized tanks:
- Expansion vessels
- Flow regulators
- Safety valves
- Automatic air vents
- Glycol-based heat transfer fluids (proper drain-back systems are operated with regular water)
- Filling valves
- Sacrificial anodes
These components usually add €700-1000 to the installation cost, causing the customer to accept future maintenance issues as these parts have to be replaced at intervals of 5 to 10 years at least.
Going even further, when combining steel storage tanks with underfloor heating, separation stations are required, costing another €1000-2000. These separation stations are necessary because underfloor heating pipes made of polypropylene are not oxygen-tight and would otherwise allow oxygen to enter the steel storage tank, causing immediate corrosion and sludge buildup. Using non-pressurized storage tanks made of polypropylene, which is the same material as the underfloor heating pipes, allows direct connection without separation stations. This prevents rust and sludge formation in both the underfloor heating and the storage tank, often for 40 years or more.
Since most heating engineers are experienced with steel tanks and there are only very few manufacturers producing these robust, temperature-resistant, and structurally solid layered storage tanks (without fragile inner liners), it will take some time for this approach to become widely accepted among "experts." End customers, after extensive consultations and trade show visits, often come to realize this on their own and opt for a rational construction with a drain-back system and non-pressurized storage tank, which genuinely saves them money, energy, maintenance, and trouble.
When combined with an efficient surface heating system, customers usually find themselves more than satisfied.
It is also possible on a large scale—as demonstrated by a system with a 130,000-liter (34,340-gallon) stratified storage tank and 200 heat recovery ventilators (HRVs) in Germany.
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