ᐅ Use an Air Source Heat Pump or Gas and Solar?

ares83 schrieb:
Do you have such high demands for the hot water supply?

Yes, we chose a luxury shower with a flow rate of 26 liters per minute (7 gallons per minute). Also, a 190x90 cm (75x35 inches) bathtub that will be used frequently. Four people will live in the house. The rest you can easily calculate yourself. I think a 400-liter (105-gallon) hot water tank is already borderline.

In any case, the water consumption will be so high that you shouldn’t simply overlook it in advance.

You are definitely right about that. We tend to be quite "frugal" when it comes to showering. I find showering or bathing, for example, boring, so I’m in and out of the shower just to get clean. I’m done before others have even started preparing to shower.

I couldn’t immediately find more detailed instructions, but for the various A1 models, you can find something like this:

"Article number BGAi1006506W Persons 3
Supply temperature up to W10
60°C (140°F)
Supply temperature up to B0
60°C (140°F)
Power consumption B0/W35
1.3 kW
Additional power rating standard
W10/W35 kW
Additional power rating consumption W10/W35
1.3 kW
Additional power rating
7.7 kW
Exhaust power B0/W35
5.7 kW
Minimum storage volume
170 l (45 gallons)
COP EN14511 W10/W35
6.20
COP EN14511 B0/W35
4.60
Groundwater flow rate
1.8 m³/h (Δt=3K) (≈ 2.4 yd³/h (Δt=3K))
Heating water flow rate
1.3 m³/h (Δt=5K) (≈ 1.7 yd³/h (Δt=5K))"

And so on, but this already means that at 0°C (32°F) brine temperature, you can get 60°C (140°F) water temperature without an electric heating element.

The following was shared with me today by an energy consultant:

"Heat Load Calculation:

As suspected, there are already some deficiencies and errors here, which is why this cannot be considered professionally done (attachment).

In particular, the controlled residential ventilation system with heat recovery was not taken into account.

Whether there are further errors regarding the building component geometry, I cannot assess.


Heating Surface Dimensioning:

There are also some shortcomings here. The only positive aspect is the selected flow temperature (VLT), assuming the heat generator will be a heat pump.

I did not verify whether the software calculates correctly. Many software programs use the same incorrect calculation core.

Inactive or limited-functioning underfloor heating (UFH) surfaces were not taken into account.


Pipe Network Calculation:

Since initial errors tend to be carried through and even multiplied, I have not reviewed this.

Modern heat generators today usually have an integrated heating circuit pump. The available residual pumping head is specific to the manufacturer and the device. This correlation is missing here.


Geothermal Probes:

The probes should be sized according to the actual required extraction energy for heating and domestic hot water, which is not the case here.

On the positive side, borehole grouting and possibly two boreholes are planned. The latter is more economically sensible but somewhat more expensive.

Before focusing more intensively on this, the actual energy demand for heating and domestic hot water should perhaps first be determined.


Conclusion:

Overall, very comprehensive and sophisticatedly prepared and presented, but unfortunately with some, at times significant, deficiencies."

This topic will therefore continue to occupy me intensively and will probably not be productive without paid support from such a specialist who accompanies the process from A to Z.

Oh dear, okay. But you noticed it, that’s good.
The heating load decreases further with controlled residential ventilation. So, a proper heating load calculation and design of the underfloor heating system are necessary.

I have only read the first few pages of the thread, but I am surprised by the energy consumption figures.
When I read about ground source heat pumps or air-to-water heat pumps with monthly energy costs of 80-120€ and this for new builds?
A few years ago, I bought a house with 152 sqm (1635 sq ft) of living space including a converted attic, and I also heat my basement to 19.5°C (67°F). In total, 209 sqm (2250 sq ft) are heated.
About the house and heating system: built in 1992, with an Atmos boiler from 1980s technology.
Only traditional radiators are used.
Supply temperature is about 60°C (140°F), if the gauge can be trusted. No pipe insulation or additional thermal insulation...
Additionally, I have a gas water heater with 160 liters (42 gallons), also built in 1992, based on 1980s technology.
My roof has significant insulation damage caused by a marten.
Nevertheless, my total gas consumption is about 1550-1650 m³ (55,000-58,300 cu ft), roughly equivalent to 16,000-18,000 kWh. My gas costs amount to around 85€ per month.
When I see how much more a heat pump costs here, and considering some new KfW standards, I wonder if the construction was done properly or if the heating system was poorly calculated at all.

Best regards, Edison

That is already exceptional for your house and indicates a good heating system.

Conversely, anyone with a reasonable heat pump in a properly insulated house today should not have heating costs exceeding 600€ per year.
1200€ for a 140m² (1507 sq ft) house simply does not add up.