ᐅ New Single-Family Home Built to KfW55 Standard – Which Heating System to Choose?
Created on: 19 Jul 2020 12:19
T
Traube348
Hello everyone,
I have read many articles and would now like to benefit from the extensive knowledge of the members here.
A brief overview of my building project:
- Single-family house with approximately 160sqm (1,722 sq ft) of living space
- No basement, 2 full floors with an unfinished attic
- Relatively large window areas and an open-plan design with a staircase in the living area
- Underfloor heating throughout the house with tile flooring
- KfW 55 standard with timber frame construction
- A wood-burning stove will be installed
Unfortunately, I have little experience in this area and rely on recommendations from others regarding heating.
On the ground floor, we have a utility room of 8sqm (86 sq ft) where we would like to accommodate all the technical equipment.
The builder recommends installing a central ventilation system, which we would like to do.
Now to my question:
There is a gas connection in our building area, and a friend told me we should definitely heat with a gas boiler. To meet the KfW standard, according to the energy consultant, we still need to install 9sqm (97 sq ft) of solar panels on the roof.
A heating engineer friend advises: choose an air-to-water heat pump – split system Weishaupt LS 8-BREK – so you can avoid the solar requirement.
I have requested quotes for both options from different heating engineers, and they come out roughly the same in price.
Since I have heard many statements opposing air-to-water heat pumps, I tend to prefer gas.
However, the main challenge is the limited space in the utility room. In addition to the heating system, the two-flue fireplace, and the ventilation system, the electrical control cabinet as well as the washing machine and dryer are also planned to be located there.
Is there anyone who has faced a similar space issue?
What would you recommend?
Thank you very much in advance for your help.
I have read many articles and would now like to benefit from the extensive knowledge of the members here.
A brief overview of my building project:
- Single-family house with approximately 160sqm (1,722 sq ft) of living space
- No basement, 2 full floors with an unfinished attic
- Relatively large window areas and an open-plan design with a staircase in the living area
- Underfloor heating throughout the house with tile flooring
- KfW 55 standard with timber frame construction
- A wood-burning stove will be installed
Unfortunately, I have little experience in this area and rely on recommendations from others regarding heating.
On the ground floor, we have a utility room of 8sqm (86 sq ft) where we would like to accommodate all the technical equipment.
The builder recommends installing a central ventilation system, which we would like to do.
Now to my question:
There is a gas connection in our building area, and a friend told me we should definitely heat with a gas boiler. To meet the KfW standard, according to the energy consultant, we still need to install 9sqm (97 sq ft) of solar panels on the roof.
A heating engineer friend advises: choose an air-to-water heat pump – split system Weishaupt LS 8-BREK – so you can avoid the solar requirement.
I have requested quotes for both options from different heating engineers, and they come out roughly the same in price.
Since I have heard many statements opposing air-to-water heat pumps, I tend to prefer gas.
However, the main challenge is the limited space in the utility room. In addition to the heating system, the two-flue fireplace, and the ventilation system, the electrical control cabinet as well as the washing machine and dryer are also planned to be located there.
Is there anyone who has faced a similar space issue?
What would you recommend?
Thank you very much in advance for your help.
Bookstar schrieb:
With an air-to-water heat pump, you often end up with double the heating costs in new buildings compared to gas, even with correct pipe spacing and heat load calculation. Only through your own optimization can this be balanced out. It’s disappointing, but often the reality.
Actually, the best heating technology is still pellets. Reliable, affordable, and flexible. Underground tank in the garden, ready to go.
With a heat pump, you also face the big risk of electricity price increases. No other energy source gets more expensive as quickly as good electricity.So far, I didn’t want to disagree, but now I feel compelled to respond.
Regarding heat pumps: replace your “optimization” with a one-time proper setup, and it works fine. But as you said, it takes time.
Pellets reliable, flexible, affordable? Sorry, but NO! Often need cleaning, issues with suction or transport screws, chimney sweep visits four times a year, often long transport distances, expensive installation costs.
N
nordanney20 Jul 2020 21:10Bookstar schrieb:
With an air-to-water heat pump, you often end up with double the heating costs in a new build compared to gas, even with proper pipe spacing and heat load calculation. That’s complete nonsense. As if only idiots would install these systems. Choosing a lower heating curve takes two minutes; the last 5-10% efficiency doesn’t make a big difference—whether heating costs are 30 or 32€ per month.
Bookstar schrieb:
Actually, pellet heating is still the best technology. Reliable, affordable, and flexible. Underground tank in the garden, done. Expensive, prone to problems, and requires the most space.
What about the compressor, bypass valve, thermostats, heating curve, domestic hot water, hydraulic balancing, and so on? All of these need to be properly set up; otherwise, the heat pump will cost you a fortune.
Many people then find they cannot get their bathroom warm. These are all problems solely related to the heat pump.
Pellets are similarly expensive as a good air-to-water heat pump. The space requirement is minimal. Have you looked at the latest systems? Technically, they are no longer prone to malfunctions...
The real disadvantage is that you need a chimney. But a heat pump without a wood stove would be unthinkable for me in winter, so we also need a chimney for that.
Many people then find they cannot get their bathroom warm. These are all problems solely related to the heat pump.
Pellets are similarly expensive as a good air-to-water heat pump. The space requirement is minimal. Have you looked at the latest systems? Technically, they are no longer prone to malfunctions...
The real disadvantage is that you need a chimney. But a heat pump without a wood stove would be unthinkable for me in winter, so we also need a chimney for that.
Lumpi_LE schrieb:
have 300 liters, 2 adults, 2 children – usually not enough for 24 hours. With gas it wouldn’t matter, Here it is again, the playing around. If 300 liters (79 gallons) aren’t enough, the circulation needs to be reduced. I had problems with this until recently as well. I stopped preparing hot water overnight because it’s naturally colder then and therefore more expensive. But the circulation drained the buffer tank. Over 10 hours, the temperature dropped by more than 10°C (18°F). Currently, by reducing the circulation, I have managed to extend this to over 15 hours.
Tolentino schrieb:
Really? How is the water temperature set on your system? Up to what temperature does the heat pump heat the water, and at what temperature does it start? Ybias78 schrieb:
We will probably have a kfw40plus house. We’re not big fans of bathtubs. From what I’ve read online, 175 liters (about 46 gallons) is more than enough. tomtom79 schrieb:
Here it comes again, the guessing game. If 300 liters (about 79 gallons) aren’t enough, the circulation needs to be reduced. We don’t have circulation.
As I mentioned before: with gas systems, 175 liters (about 46 gallons) is not a problem because the tank simply recharges when it’s half empty—you don’t really notice it, unless you’re using a rain shower head and filling two bathtubs at once.
For heat pumps, it’s always recommended to use a larger storage tank.
Our tank is set to 48°C (118°F) and charges around midday, when the photovoltaic system reduces peak loads.
Of course, individual usage also plays a role. I usually shower for a few minutes, so I don’t use much water. My wife sometimes runs the rain shower for 20 minutes; in that case, the 300-liter (about 79 gallons) tank is emptied.
To put it another way: at a flow rate of 20 liters per minute (about 5 gallons per minute) and a shower temperature of 38°C (100°F), a 175-liter (about 46 gallons) tank set at 48°C (118°F) will run out in 11 minutes—then you have to wait 20–30 minutes for hot water again, or longer, depending on the heat pump settings.
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