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
R
R.Hotzenplotz20 Jun 2018 22:00I have now received an updated heating concept with a lot of documents. What exactly should I be looking for to make sure that I can safely replace a gas heating system with a heat pump in 20 years? This is not clear at all for a layperson. I’m happy to share the relevant documents.
There is a so-called "pipe network calculation," which lists the following calculation parameters at the top:
Flow temperature 35°C (95°F)
Return temperature 30°C (86°F)
They also sent me a "heating diagram"—a sheet full of technical jargon.
Heating surface design
Heating load calculation
There is a so-called "pipe network calculation," which lists the following calculation parameters at the top:
Flow temperature 35°C (95°F)
Return temperature 30°C (86°F)
They also sent me a "heating diagram"—a sheet full of technical jargon.
Heating surface design
Heating load calculation
A
Aliban201421 Jun 2018 18:02R.Hotzenplotz schrieb:
I have just received an updated heating system concept. There are endless documents. What exactly should I look for to see if I can safely replace a gas heating system with a heat pump in 20 years? This is not clear to a layperson. I’m happy to share the relevant documents.
There is a so-called "pipe network calculation" that lists the calculation parameters at the top:
Supply temperature 35°C (95°F)
Return temperature 30°C (86°F)
Then they sent me a "heating schematic." A sheet full of technical jargon.
Heating surface design
Heating load calculationOne of the previous posters already mentioned that it’s probably more about whether the heating system’s supply temperature of, for example, 35°C (95°F) in the living areas/bathroom can achieve the room temperatures you want (24°C (75°F) in the bathroom? The rest 20-22°C (68-72°F)?).
To exaggerate:
With a 30°C (86°F) supply temperature for underfloor heating, you won’t get a 35°C (95°F) room temperature.
In new builds with good insulation and tight pipe spacing, most people can reach 21-22°C (70-72°F) room temperature even with a supply temperature of 28-35°C (82-95°F).
The closer the pipe spacing, the lower the required supply temperature, since more heat transfers through the floor. If the pipe spacing is wider, you have to increase the supply temperature.
The plumbing companies we worked with always referred to pipe spacing as the critical factor when switching from gas to heat pump. Pipe spacing cannot be easily changed later. To me, that meant the rest can be “easily” changed afterwards.
This made sense to me because, as mentioned,
a heat pump would operate very inefficiently if the pipe spacing were, say, 20cm (8 inches), to exaggerate. Gas would probably be cheaper then, but far from reasonable, to make the point.
All information given without guarantee.
It’s best to ask your heating specialist again about what conditions (in their opinion) are necessary for a switch, just to be sure.
P
pagoni202014 Jun 2020 13:32€uro schrieb:
Hello, It’s natural that everyone considers their own concept the best!
From a pure investment perspective, air source heat pumps and gas plus connection costs are usually comparable. To properly assess the investment in a technical solution, the actual demand (capacity, energy) for heating and hot water must be known.
That’s incorrect. Both the Energy Saving Ordinance and KfW require compliance with two parameters: Ht´ and qp´´! Who is to blame?
Gas has the fundamental disadvantage that usually a solar thermal system must be installed as well, unless you rely on the 15% rule. If you want to stay with gas, you should definitely implement this to avoid an uneconomical solar thermal system.
General statements without evidence are completely pointless! Hello, here the problems start. If air source heat pump, then only with full modulation! Unfortunately, these providers cannot offer that!
This is a key criterion alongside financing costs. However, it can only be answered once the essential basics are clarified => actual demand. Until then, it’s all guesswork, assumptions, and speculation. Overall, there is no reliable or sound basis for a major investment decision.
Best regards,
NB: Forum posts do not replace the necessary planning and sizing of the system. Some “advice” from anonymous hobby experts lacks any foundation Oops... could you please explain the 15% rule regarding gas and solar thermal systems? I’m considering using liquid gas for a new build, since there’s no gas connection and I might prefer not to have a blower in front of the house. We have it like this here currently, and it works perfectly fine. Our plot is large, so burying a tank wouldn’t be a problem.
pagoni2020 schrieb:
Oops... could you please explain the 15% rule in relation to gas and solar thermal systems? I am considering using propane for the new build since there is no natural gas connection and I might not want a forced-air unit outside the house. We currently have this setup here and it works completely fine. Our plot is large, so burying the tank wouldn’t be an issue.With a large plot, you might want to consider a ground source heat pump and look into information about the horizontal collector system (trench collector).
Today, I visited a local construction company to get a quote. I was interested in having a photovoltaic system combined with an air-to-water heat pump. Both the architect and the managing director of the construction company said that the additional costs for the air-to-water heat pump would never be recovered through savings on utility bills. They explained that gas heating combined with photovoltaic results in roughly €200-300 (about $215-320) higher heating costs. They proposed a gas boiler along with a photovoltaic system of around 10 kW plus a battery storage unit.
Now I’m a bit confused. Is an air-to-water heat pump really that unprofitable?
Now I’m a bit confused. Is an air-to-water heat pump really that unprofitable?
Would you install a gas connection if you don’t have a gas heating system? If not, you should also consider that a gas connection, along with maintenance for gas and heating, involves ongoing costs. I actually don’t think that an air-to-water heat pump is more expensive overall. Plus, the synergy between an air-to-water heat pump and photovoltaic systems is greater than with gas; for example, you can often heat the hot water storage tank with solar power around midday.
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