Hello,
We are starting to get really frustrated... every builder tells us something different...
We want to build a 130sqm (1,399 sq ft) KfW 70 house with the living room facing south, and we are unsure whether to choose gas or an air source heat pump. Some providers, at almost the same price level, offer us air source heat pumps and claim that the annual costs are significantly (30%) lower compared to gas, while others doubt this.
We understand that insulation with gas/solar systems is usually better because an air source heat pump boosts efficiency more towards KfW 70 standards compared to gas/solar, which might argue in favor of gas. An air source heat pump might fail somewhat sooner, and in case of problems, you can usually get quick and competent local support with gas. With air source heat pumps, there could be more difficulties. Additionally, the noise of air source heat pumps (in our case about 3 meters (10 feet) from the neighbor) is not insignificant. Some say that sooner or later, everyone ends up having issues with neighbors for this reason.
We are interested in air source heat pumps with storage tanks from these providers: Vaillant, Mitsubishi Zubadan, and Rotex.
What we are really curious about is the annual cost for heating and hot water with both systems.
We live near Kassel.
What should we choose, and what would be cost-effective TODAY? What is your opinion on Vaillant?
Regards
Gigi
We are starting to get really frustrated... every builder tells us something different...
We want to build a 130sqm (1,399 sq ft) KfW 70 house with the living room facing south, and we are unsure whether to choose gas or an air source heat pump. Some providers, at almost the same price level, offer us air source heat pumps and claim that the annual costs are significantly (30%) lower compared to gas, while others doubt this.
We understand that insulation with gas/solar systems is usually better because an air source heat pump boosts efficiency more towards KfW 70 standards compared to gas/solar, which might argue in favor of gas. An air source heat pump might fail somewhat sooner, and in case of problems, you can usually get quick and competent local support with gas. With air source heat pumps, there could be more difficulties. Additionally, the noise of air source heat pumps (in our case about 3 meters (10 feet) from the neighbor) is not insignificant. Some say that sooner or later, everyone ends up having issues with neighbors for this reason.
We are interested in air source heat pumps with storage tanks from these providers: Vaillant, Mitsubishi Zubadan, and Rotex.
What we are really curious about is the annual cost for heating and hot water with both systems.
We live near Kassel.
What should we choose, and what would be cost-effective TODAY? What is your opinion on Vaillant?
Regards
Gigi
[QUOTEYou can relatively quickly get rid of an uneconomical car, but with a building it is much more difficult][/QUOTE]
That’s true!
A well-known heating and plumbing expert told me: I would choose a gas boiler. If it breaks down in winter, help is quickly available. With an air source heat pump, there could definitely be more difficulties.
Still, I can’t stop thinking about the air source heat pump.
Maybe I should first install a gas boiler and after 10–15 years add a well-developed air source heat pump and connect it to the gas boiler at low temperatures. Is that even possible?
What I’m also curious about:
Is it possible to completely switch off the electric heater in an air source heat pump, or does Vaillant have problems with that at very cold temperatures? I don’t know Vaillant at all. What are the experiences?
Background:
My relative has a ground source heat pump (deep drilling) and has turned off the electric heater during winter for 3 years. We had -20°C (–4°F) last winter and -18°C (0°F) the winter before, and it worked for him.
His average energy cost (water/heating) is 1000€/year for a 160 sqm (1722 sq ft) KfW70 house (14 cents/kWh tariff and three-person household).
That’s true!
A well-known heating and plumbing expert told me: I would choose a gas boiler. If it breaks down in winter, help is quickly available. With an air source heat pump, there could definitely be more difficulties.
Still, I can’t stop thinking about the air source heat pump.
Maybe I should first install a gas boiler and after 10–15 years add a well-developed air source heat pump and connect it to the gas boiler at low temperatures. Is that even possible?
What I’m also curious about:
Is it possible to completely switch off the electric heater in an air source heat pump, or does Vaillant have problems with that at very cold temperatures? I don’t know Vaillant at all. What are the experiences?
Background:
My relative has a ground source heat pump (deep drilling) and has turned off the electric heater during winter for 3 years. We had -20°C (–4°F) last winter and -18°C (0°F) the winter before, and it worked for him.
His average energy cost (water/heating) is 1000€/year for a 160 sqm (1722 sq ft) KfW70 house (14 cents/kWh tariff and three-person household).
gigi schrieb:
...A heating and plumbing expert I know told me: I would choose a gas heating system. If it fails in winter, there is quick support. With an air-source heat pump, there could certainly be more problems. Not known to me, even air-source heat pumps have quick support available. Besides, how often does a precisely planned heating system actually fail?gigi schrieb:
...Maybe I should first install a gas heating system and after 10-15 years buy a well-developed air-source heat pump and connect it with the gas heating system for very low temperatures. Well-developed air-source heat pumps already exist today. Unfortunately, these are rarely found in general contractor projects because almost any cheap product is pushed onto the uninformed homeowner.gigi schrieb:
...Is that even possible? In principle, yes; however, whether it makes sense is questionable. At the very least, heating surfaces and pipe hydraulics must be "heat-pump-compatible".gigi schrieb:
...Can the electric heating element of an air-source heat pump be completely turned off, or are there problems with Vaillant models at very low temperatures? The fear of the "evil" electric heater leads to some strange ideas, which usually only benefit the installer financially and give the user a poor seasonal performance factor. A typical example are the on/off "sewing machines" in general contractor projects. In well-designed systems, the electric heater contributes just 0.2% up to at worst 2% of the annual heating energy. So, no reason to panic.gigi schrieb:
...My relative has a ground-source heat pump (deep borehole) and has had the electric heating element switched off during winter for three years. Last winter we had -20°C (−4°F) and the winter before -18°C (0°F), and it worked fine for him. Ground-source heat pumps generally do not require an electric heating element, except possibly during the warm-up phase to protect the heat source. Good installers lend this feature for that purpose; poor ones sell systems with it, even if its use is not necessary.gigi schrieb:
...His average energy cost (water/heating) is 1000€/year for a 160sqm (1720sqft) KfW70 house (14 cents/kWh tariff and a household of three persons). Goodness, in this case I would hold the responsible party highly accountable for this poor result. At best, one-third of this should be expected, assuming the building is not located at the Zugspitze, room temperatures of 30°C (86°F) are not demanded, windows are not left open during winter, and there are no excessive bathing rituals. How can he still sleep peacefully? Probably saved a few euros on precise system planning, so he should consider this a valuable lesson.M
Micha&Dany18 Jul 2012 06:09Hello Euro
That’s why I wrote that I assume the best possible planning. But even with the best planning, you still have heating costs to pay—no matter how high or low they end up being. I also mentioned that a heat pump requires more precise planning than gas heating.
That brings us back to my point—I can’t estimate my demand yet because there are many parameters that will be new to me (wood stove, bathing habits, controlled ventilation system).
I don’t yet know how many baths or showers per week will make me feel comfortable, or how much wood I will be comfortable chopping for the stove. (If I chop more wood, I’ll sweat more—so I’ll need to bathe more.)
That’s exactly what I mean. Since I have no experience with many parameters, I can only guess—and be completely wrong—so the demand planning is basically pointless.
I might know the fuel consumption of a car, but only to a certain extent, because consumption also depends on my individual driving style! Even if you and I had the same car, your driving habits would surely be different from mine—and we would definitely have different consumption with the same vehicle!
But even if I know the exact consumption, if I have no idea how much I will actually drive, I can only guess the fuel costs—but not reliably estimate or calculate them. To make calculations, I would need to know how many kilometers (miles) I drive per month and how much of that is in the city versus on the highway (and on which highway? I would have very different consumption on the A40 compared to highways where I’m less stuck in traffic :rolleyes).
Regards Micha
Energy prices for all sources will rise sharply. You can relatively quickly get rid of an uneconomical car, but with a building, that becomes much more difficult. [/QUOTE]
€uro schrieb:
How else can you find an economical system, evaluate an investment? I would prefer the option with 50 Euro. Also, you do not have to live with some undefined consumption later, but can influence it yourself during the planning phase.
That’s why I wrote that I assume the best possible planning. But even with the best planning, you still have heating costs to pay—no matter how high or low they end up being. I also mentioned that a heat pump requires more precise planning than gas heating.
€uro schrieb:
Higher demand always leads to higher consumption. 25°C (77°F) indoor temperature requires more energy than 20°C (68°F). That’s why, for example, the desired room temperatures are agreed upon when calculating heating loads.
That brings us back to my point—I can’t estimate my demand yet because there are many parameters that will be new to me (wood stove, bathing habits, controlled ventilation system).
€uro schrieb:
But you can answer these in advance by defining a general comfort scenario for yourself.
I don’t yet know how many baths or showers per week will make me feel comfortable, or how much wood I will be comfortable chopping for the stove. (If I chop more wood, I’ll sweat more—so I’ll need to bathe more.)
€uro schrieb:
Anything that deviates from this later means a change in consumption.
That’s exactly what I mean. Since I have no experience with many parameters, I can only guess—and be completely wrong—so the demand planning is basically pointless.
€uro schrieb:
Who buys a car without knowing the fuel consumption in advance? Someone who drives little might be okay with a cheap gas guzzler, while someone who drives a lot will necessarily pay attention to low consumption values and therefore prefer a somewhat more expensive model.
I might know the fuel consumption of a car, but only to a certain extent, because consumption also depends on my individual driving style! Even if you and I had the same car, your driving habits would surely be different from mine—and we would definitely have different consumption with the same vehicle!
But even if I know the exact consumption, if I have no idea how much I will actually drive, I can only guess the fuel costs—but not reliably estimate or calculate them. To make calculations, I would need to know how many kilometers (miles) I drive per month and how much of that is in the city versus on the highway (and on which highway? I would have very different consumption on the A40 compared to highways where I’m less stuck in traffic :rolleyes).
Regards Micha
Energy prices for all sources will rise sharply. You can relatively quickly get rid of an uneconomical car, but with a building, that becomes much more difficult. [/QUOTE]
Hello Gigi,
before you start looking for construction companies and receive a complete offer for the house including the heating system—or even let them choose the heating system for you—you should try consulting an HVAC planner first. Only this way will you get exactly what you really want.
Quite often, you read in other forums about homeowners who were not very satisfied with general contractors (GCs)—these are companies where you have only one point of contact who works directly for you—because the advice, especially regarding building services engineering, was not as initially promised. Unfortunately, these GCs often employ salespeople who usually know no more about the technical aspects than you do. That’s why building services are often excluded from GC contracts and instead managed separately by a specialist planner.
Such a planner can determine the essential design details for the system as part of an energy calculation before further planning proceeds. They can also provide cost forecasts for different options, both for the initial investment and for ongoing expenses. When comparing costs, you should consider the evaluation period: heating systems typically last about 25 years, which might be the appropriate timeframe. However, the question is how long you plan to use the house, as this can affect the evaluation period. Another important consideration is whether you want underfloor heating or radiators, as this will impact the choice of heating system. Heat pumps, in particular, should be combined with surface heating to ensure optimal efficiency. This can be a crucial detail in adapting the heating system effectively to the building.
A specialist planner can also assist with possible subsidies, as often only minor adjustments are needed to qualify for funding—but just as easily, the subsidy may be missed. As was already mentioned, if you use a gas heating system, you need to meet even stricter energy-saving regulation requirements to qualify for subsidies without a solar thermal system. It’s advisable to get help from a specialist planner during this planning phase to make sure everything goes smoothly.
Best regards
before you start looking for construction companies and receive a complete offer for the house including the heating system—or even let them choose the heating system for you—you should try consulting an HVAC planner first. Only this way will you get exactly what you really want.
Quite often, you read in other forums about homeowners who were not very satisfied with general contractors (GCs)—these are companies where you have only one point of contact who works directly for you—because the advice, especially regarding building services engineering, was not as initially promised. Unfortunately, these GCs often employ salespeople who usually know no more about the technical aspects than you do. That’s why building services are often excluded from GC contracts and instead managed separately by a specialist planner.
Such a planner can determine the essential design details for the system as part of an energy calculation before further planning proceeds. They can also provide cost forecasts for different options, both for the initial investment and for ongoing expenses. When comparing costs, you should consider the evaluation period: heating systems typically last about 25 years, which might be the appropriate timeframe. However, the question is how long you plan to use the house, as this can affect the evaluation period. Another important consideration is whether you want underfloor heating or radiators, as this will impact the choice of heating system. Heat pumps, in particular, should be combined with surface heating to ensure optimal efficiency. This can be a crucial detail in adapting the heating system effectively to the building.
A specialist planner can also assist with possible subsidies, as often only minor adjustments are needed to qualify for funding—but just as easily, the subsidy may be missed. As was already mentioned, if you use a gas heating system, you need to meet even stricter energy-saving regulation requirements to qualify for subsidies without a solar thermal system. It’s advisable to get help from a specialist planner during this planning phase to make sure everything goes smoothly.
Best regards
Micha&Dany schrieb:
....I’m not sure yet .... Reading all this, it seems there is a complete lack of knowledge here. But even in that case, you can work with typical average values. The worst-case scenario is also, as mentioned before, possible to outline. This at least allows you to estimate a minimum-to-maximum range. However, if someone prefers to be surprised due to complete ignorance, that’s their choice. But these “surprises” are usually negative.
I also deal a lot with poorly executed practical installations, where frustration, annoyance, and disappointment are common. A main issue is excessively high consumption costs despite significant investments. This is completely different from what was originally suggested.
If it becomes too much for you, you can always chop more wood. The problem is, the utilization rate—not to be confused with the combustion efficiency—might only be around 50%.
From experience, after the initial enthusiasm fades, wood chopping usually declines after 2 to 3 years.
v.g.
@€uro
There are so many variables here. How close do your calculations really come to the actual consumption?
Have you ever calculated a system upfront and then recalculated after a few years to see if it was really the right decision?
With the "botched real-life systems," you are always wiser than the planner because you know the actual figures.
Do you see what information the homeowner provided to the planner back then and which price increases were factored in?
How similar are the different systems really?
Is it possible that one system looks attractive based on my predictions, but considering a worst-case scenario, another system would make more sense? And according to actual usage patterns, a third system would be best?
Could it even be that one system makes sense at first? But if another child is planned or unplanned later, a different system might become attractive. Or I become more heat-loving as I age, and the average temperature is a few degrees warmer than originally planned. How do you want to factor that in?
We currently live in an uninsulated natural stone house in a river valley. Unless the heating runs continuously during extreme cold at night, the temperature drops so quickly after turning off the heating around 9:00 PM that I have to heat higher beforehand than I actually need to. I don’t want the bedroom to be freezing. So in the evening I have to preheat to over 20°C (68°F) so that the temperature in the morning does not fall far below 10°C (50°F).
Even now, I can’t say what my average temperature is.
I don’t have a bathtub at the moment, nor a child.
And you want to know now how things will be later with an insulated house, a child, underfloor heating, a fireplace, and a bathtub?
There are so many variables here. How close do your calculations really come to the actual consumption?
Have you ever calculated a system upfront and then recalculated after a few years to see if it was really the right decision?
With the "botched real-life systems," you are always wiser than the planner because you know the actual figures.
Do you see what information the homeowner provided to the planner back then and which price increases were factored in?
How similar are the different systems really?
Is it possible that one system looks attractive based on my predictions, but considering a worst-case scenario, another system would make more sense? And according to actual usage patterns, a third system would be best?
Could it even be that one system makes sense at first? But if another child is planned or unplanned later, a different system might become attractive. Or I become more heat-loving as I age, and the average temperature is a few degrees warmer than originally planned. How do you want to factor that in?
We currently live in an uninsulated natural stone house in a river valley. Unless the heating runs continuously during extreme cold at night, the temperature drops so quickly after turning off the heating around 9:00 PM that I have to heat higher beforehand than I actually need to. I don’t want the bedroom to be freezing. So in the evening I have to preheat to over 20°C (68°F) so that the temperature in the morning does not fall far below 10°C (50°F).
Even now, I can’t say what my average temperature is.
I don’t have a bathtub at the moment, nor a child.
And you want to know now how things will be later with an insulated house, a child, underfloor heating, a fireplace, and a bathtub?
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