ᐅ Recommendation: Air-to-Water Heat Pump versus Local District Heating Network for KFW40 New Construction
Created on: 29 Oct 2023 08:16
M
Mark_xx
Hello everyone,
We are about to start construction on our single-family house.
Key facts:
2 full floors
200 sqm (2,150 sq ft)
No basement
KfW40 standard
3 people
Photovoltaic system 7-9 kWp (depending on heat pump or district heating), battery storage optional
Underfloor heating throughout the house
There are two specific energy supply options we have been offered:
Option 1: District heating
Technology: Transfer station, meter, and downstream combined storage tank for heating and hot water (CS Solar KSR 1000), plus two 3 kW heating rods with control for feeding in photovoltaic electricity. Supply temperature from the district heating network: 65-80 degrees Celsius (149-176 degrees Fahrenheit)
Flat price per kWh independent of consumption: 300 euros + €0.0995/kWh
One-time connection fee including transfer station: 14,000 euros
Option 2: Air-to-water heat pump
Technology: iDM ALM 4-12 with integrated storage tanks (100 l (26 gallons) heating, 295 l (78 gallons) hot water)
Comparable price: 18,000 euros
Overall costs over the service life, assuming a heat pump lifespan of 15 years, favor district heating.
However, I have two questions:
I am not sure whether a combined storage tank is really practical with district heating, especially in summer. For example, do you have to heat the entire buffer tank to temperature for showering even if the heating water isn’t needed? Could this possibly lead to issues with legionella?
Also, there is a claim that a photovoltaic system works more efficiently with an air-to-water heat pump than with a heating element, because the PV system likely does not produce 3-6 kW at the time of the heat demand.
Does anyone have experience with one of these options or answers to my two questions?
I would also appreciate any suggestions for improvement.
Thank you!
We are about to start construction on our single-family house.
Key facts:
2 full floors
200 sqm (2,150 sq ft)
No basement
KfW40 standard
3 people
Photovoltaic system 7-9 kWp (depending on heat pump or district heating), battery storage optional
Underfloor heating throughout the house
There are two specific energy supply options we have been offered:
Option 1: District heating
Technology: Transfer station, meter, and downstream combined storage tank for heating and hot water (CS Solar KSR 1000), plus two 3 kW heating rods with control for feeding in photovoltaic electricity. Supply temperature from the district heating network: 65-80 degrees Celsius (149-176 degrees Fahrenheit)
Flat price per kWh independent of consumption: 300 euros + €0.0995/kWh
One-time connection fee including transfer station: 14,000 euros
Option 2: Air-to-water heat pump
Technology: iDM ALM 4-12 with integrated storage tanks (100 l (26 gallons) heating, 295 l (78 gallons) hot water)
Comparable price: 18,000 euros
Overall costs over the service life, assuming a heat pump lifespan of 15 years, favor district heating.
However, I have two questions:
I am not sure whether a combined storage tank is really practical with district heating, especially in summer. For example, do you have to heat the entire buffer tank to temperature for showering even if the heating water isn’t needed? Could this possibly lead to issues with legionella?
Also, there is a claim that a photovoltaic system works more efficiently with an air-to-water heat pump than with a heating element, because the PV system likely does not produce 3-6 kW at the time of the heat demand.
Does anyone have experience with one of these options or answers to my two questions?
I would also appreciate any suggestions for improvement.
Thank you!
P
Pinkiponk15 Aug 2024 10:10For me, it is a deal-breaker to be dependent on a monopoly provider (district heating).
Pinkiponk schrieb:
For me, it is a deal-breaker to be dependent on a monopoly provider (district heating).I agree. But if it really is the only option, you are not exactly at the mercy of the supplier—you just need to ensure there is the possibility to switch to another supply method (and space to install your own boiler or similar). Being free from all the chimney-related hassle is generally a good thing. District heating just has to be actual local district heating, not something more like near-local or medium-distance heating; and the contract should be a contract, not a pact with the devil.https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
hanghaus2023 schrieb:
@batomek Do you have a condensing boiler? I don’t think I have a condensing boiler, but honestly, I’m not sure. How could I tell?
hanghaus2023 schrieb:
@batomek
How large is the house?
At the moment, it’s 280 sqm (3,014 sq ft). After adding an extension to the garage, it will be just under 360 sqm (3,875 sq ft). So it’s quite a big place. Upstairs with the extension, ground floor, basement, and a practice room in the cellar. Exposed roof structure and double-glazed wooden windows all around.
Lately, it’s been unbearably hot upstairs (29-30°C (84-86°F)), so I’ve been considering one or more multi-split air conditioning units. Feels like there are many issues with the heating system right now. I’m planning to contact an energy consultant soon and hope they can help me out.
11ant schrieb:
I agree with that. But if it really is the only option, you’re not trapped—you just need to ensure the flexibility to switch to another supply method (and have space prepared for your own boiler or something similar). Being free from all that chimney-related hassle is basically a good thing in principle. The local heat supply just needs to be local heat supply, not “nearby” heat or medium-distance heat; and the contract should be a contract, not a pact with the devil. The local heat supply is actually supposed to be connected by autumn. So far, however, no excavation work has started. Neither the wood chip plant nor the pipelines have been completed. There are also no contract drafts yet.
At the moment, I would lean towards a heat pump (either ground-source or air-source) combined with photovoltaics and a storage system. I’m curious to see if the energy consultant can help me further at this point.
Similar topics