Hello everyone,
Since I’m a bit unsure and our installer said everything is normal, I’m reaching out to you. We have been living in our newly built house since early 2021. It is a traditionally constructed house built to the KFW55 standard. The heated living area is about 140 m² (1507 sq ft).
We have underfloor heating throughout and a Dimplex air-to-water heat pump (LA 9S-TU). In 2021, the heat pump’s electricity consumption was 5715 kWh.
To be honest, we expected the electricity consumption to be somewhat lower. However, finding comparison values is quite difficult.
What are your experiences with the electricity consumption of your heat pump? Is this realistic?
Thanks very much for sharing your experience!
Best regards,
Michael
Since I’m a bit unsure and our installer said everything is normal, I’m reaching out to you. We have been living in our newly built house since early 2021. It is a traditionally constructed house built to the KFW55 standard. The heated living area is about 140 m² (1507 sq ft).
We have underfloor heating throughout and a Dimplex air-to-water heat pump (LA 9S-TU). In 2021, the heat pump’s electricity consumption was 5715 kWh.
To be honest, we expected the electricity consumption to be somewhat lower. However, finding comparison values is quite difficult.
What are your experiences with the electricity consumption of your heat pump? Is this realistic?
Thanks very much for sharing your experience!
Best regards,
Michael
Hello Michael,
I can’t offer the exact same heat pump, but I do have one from Dimplex. Maybe my data can help you compare a bit. Of course, I’m also happy to hear assessments from other forum members.
Model: Dimplex LA 12 STU
We live in Baden-Württemberg near Stuttgart.
House built in 2020 (completed), 32cm (13 inches) Poroton T10 bricks, without additional insulation.
205 sqm (2203 sq ft) of living space over 3 floors (basement has entrance, hallway, guest room, office).
A lot of home office work.
All rooms have thermostatic valves fully open at all times, control is only via the flow temperature. In the main bathroom, during cold months, we heat for 1.5 hours in the morning and evening with the towel heater (infrared).
When heating, the temperature in all rooms is usually around 22–22.5°C (72–73°F). Only in the basement rooms is it about 0.3°C (0.5°F) cooler.
The bedroom is the only room where we turn the thermostat down.
Since we reset all the values exactly one year ago and I have been tracking monthly data and optimizing a bit, I can say quite precisely what is set. We have only one meter because we also use a photovoltaic system for the heating. So I cannot separate household electricity and heat pump electricity exactly, but I have a fairly good estimate.
In 2022, we only fully heated in January–April and November–December. In the months in between, the heating ran only for a few days—about 20 days in total.
Residents: 2 adults, 2 small children, lots of home office.
Hot water is set to 45°C (113°F) during the day. At night, between 10 pm and 9:30 am, it drops to a night setback temperature of 39°C (102°F).
Once a week, we run a thermal disinfection cycle at 60°C (140°F).
We mostly shower, rarely take baths.
The circulation pump runs only for one hour each morning before getting up, at noon, and in the evening before showering.
Overall, it’s not that we are cold or go without warm water—living conditions are very comfortable.
We do not have a mechanical ventilation system and usually just air out briefly in the mornings and evenings.
Occasionally we supplement heating with a fireplace, but it is more decorative in the living room and only used 3–4 times a week, not as a primary heating source.
This is mainly due to the children, who might burn their fingers otherwise.
Our consumption figures:
Total electricity 8300 kWh
Of which around 4000 kWh (we do a lot of laundry and drying, cook a lot) household—so about 4300 kWh for the heat pump.
The photovoltaic system has 9.6 kWp. Thanks to it, we were able to cover about 2500 kWh ourselves and only had to buy the remaining roughly 5800 kWh.
Heat pump values:
Currently at -2°C (28°F) outside
Return temperature 25.2°C (77°F)
Flow temperature 24.8°C (76.5°F)
Setpoint 23.8°C (75°F)
Water setpoint 39°C (102°F) (night setback)
Actual: 43°C (109°F)
Heating amounts (all values refer to 12/15/21–12/14/22):
Total: 13,016 kWh
Heating: 4,966 kWh
Hot water: 8,050 kWh
Environmental energy: 9,531 kWh
Unfortunately, running times were not reset during the last maintenance, so I cannot provide annual figures here.
As said, I’m looking forward to third-party assessments as well.
I can’t offer the exact same heat pump, but I do have one from Dimplex. Maybe my data can help you compare a bit. Of course, I’m also happy to hear assessments from other forum members.
Model: Dimplex LA 12 STU
We live in Baden-Württemberg near Stuttgart.
House built in 2020 (completed), 32cm (13 inches) Poroton T10 bricks, without additional insulation.
205 sqm (2203 sq ft) of living space over 3 floors (basement has entrance, hallway, guest room, office).
A lot of home office work.
All rooms have thermostatic valves fully open at all times, control is only via the flow temperature. In the main bathroom, during cold months, we heat for 1.5 hours in the morning and evening with the towel heater (infrared).
When heating, the temperature in all rooms is usually around 22–22.5°C (72–73°F). Only in the basement rooms is it about 0.3°C (0.5°F) cooler.
The bedroom is the only room where we turn the thermostat down.
Since we reset all the values exactly one year ago and I have been tracking monthly data and optimizing a bit, I can say quite precisely what is set. We have only one meter because we also use a photovoltaic system for the heating. So I cannot separate household electricity and heat pump electricity exactly, but I have a fairly good estimate.
In 2022, we only fully heated in January–April and November–December. In the months in between, the heating ran only for a few days—about 20 days in total.
Residents: 2 adults, 2 small children, lots of home office.
Hot water is set to 45°C (113°F) during the day. At night, between 10 pm and 9:30 am, it drops to a night setback temperature of 39°C (102°F).
Once a week, we run a thermal disinfection cycle at 60°C (140°F).
We mostly shower, rarely take baths.
The circulation pump runs only for one hour each morning before getting up, at noon, and in the evening before showering.
Overall, it’s not that we are cold or go without warm water—living conditions are very comfortable.
We do not have a mechanical ventilation system and usually just air out briefly in the mornings and evenings.
Occasionally we supplement heating with a fireplace, but it is more decorative in the living room and only used 3–4 times a week, not as a primary heating source.
This is mainly due to the children, who might burn their fingers otherwise.
Our consumption figures:
Total electricity 8300 kWh
Of which around 4000 kWh (we do a lot of laundry and drying, cook a lot) household—so about 4300 kWh for the heat pump.
The photovoltaic system has 9.6 kWp. Thanks to it, we were able to cover about 2500 kWh ourselves and only had to buy the remaining roughly 5800 kWh.
Heat pump values:
Currently at -2°C (28°F) outside
Return temperature 25.2°C (77°F)
Flow temperature 24.8°C (76.5°F)
Setpoint 23.8°C (75°F)
Water setpoint 39°C (102°F) (night setback)
Actual: 43°C (109°F)
Heating amounts (all values refer to 12/15/21–12/14/22):
Total: 13,016 kWh
Heating: 4,966 kWh
Hot water: 8,050 kWh
Environmental energy: 9,531 kWh
Unfortunately, running times were not reset during the last maintenance, so I cannot provide annual figures here.
As said, I’m looking forward to third-party assessments as well.
D
Daniel-Sp14 Dec 2022 23:51BauMixx schrieb:
Our consumption is as follows:
Total electricity: 8300 kWh
Of which about 4000 kWh (we do a lot of washing, drying, and cooking) is household use – so 4300 kWh for the heat pump
Heat quantities (all values refer to the period from December 15, 2021, to December 14, 2022)
Total: 13,016 kWh
Heating: 4,966 kWh
Hot water: 8,050 kWh
Environmental energy: 9,531 kWh
Unfortunately, the operating hours were not reset during the last inspection. Therefore, I cannot provide annual values here.
As mentioned, I look forward to assessments from others. Hello,
how accurate is the estimate for the heat pump’s consumption? It would of course be better to have a submeter.
This results in a coefficient of performance (COP) of about 3.
What capacity does the heat pump have, and does it modulate its output?
Thermal disinfection in a single-family home is a hotly debated topic. Have you considered this carefully and made a conscious decision about it?
Best regards
Daniel-Sp schrieb:
Hello,
how accurate are the estimates for the heat pump’s consumption? A submeter would of course be better.
It results in an annual performance factor of about 3.
What is the heat pump’s capacity and does it modulate its output?
Thermal disinfection in a single-family home is a hot topic. Have you thought it through and made a conscious decision about it?
Regards hello,
Capacity is 12 kW (12,000 watts).
Thermal disinfection is mainly for my wife’s peace of mind. It was also recommended by the heating technician. From my research, it’s actually not really necessary and could offer further energy-saving potential 🙂
Consumption: In our 160 m² (1,722 ft²) apartment with one child, we had about 3,200 kWh of electricity consumption. Now with one more child, an additional large fridge-freezer combo, a few more lights (all LED both before and now), an extra PC, and some garden lighting. Overall, we do more laundry and drying (thanks to our photovoltaic system) and use our steam oven a lot, which we didn’t have before. So I estimate that 4,000 kWh (household electricity) is not unrealistic.
It is not modulating. With much more knowledge now, I would do that differently today. But well, you learn from mistakes.
Overall, I find the values quite reasonable for the size of the house, especially considering the low supply temperatures and the small temperature difference (delta T).
A
Alessandro15 Dec 2022 09:24Based on the recorded values, your heat pump was off.
mime270 schrieb:
2nd heat generator: 153 hours (since heating system activated around October 2020)
Flange heater: 238 hours (since heating system activated around October 2020)Umm?? Honestly, I haven’t read every post thoroughly... but what is this?
To me, flange heater sounds like a heating element.
I’ll read through the thread again carefully later, but from my layperson’s perspective, that sounds strange.
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