Hi everyone,
We are currently building our single-family home, and the shell is basically completed. Now I am working on the quotes for heating/plumbing and would appreciate your assessment regarding the sizing of the heat pump. Due to the KfW funding stop in 2022, we decided not to aim for KfW40 or 55 standards, allowing us more flexibility for DIY work and so on.
The house has three floors and is built on a slope, with the basement partly underground at the rear and exposed on the front side. The heated area in the basement consists of approximately 30m² (323 sq ft) of living space plus stairwell/hall/entrance area, while the remaining areas are unheated: technical room (14m² (150 sq ft)) and an unheated garage (62m² (668 sq ft)).
The ground floor and upper floor are fully heated.
The heated area is around 190–200m² (2045–2153 sq ft).
We have an energy certificate according to GEG2020 with the following data:
- Heated building volume: 876m³ (30,925 cu ft)
- Envelope surface area: 576m² (6,200 sq ft)
- Heated air volume: 666m³ (23,518 cu ft)
- Window area: 66m² (710 sq ft)
- Usable floor area according to the Building Energy Act (Gebäudeenergiegesetz): 280m² (3,014 sq ft)
- Primary energy demand: 44.41 kWh/(m²·a)
- Transmission heat loss coefficient: 0.345 W/(m²·K)
- Transmission heat loss: 6,951 W
- Ventilation heat loss: 5,546 W
- Additional heating load: 6,167 W
- Total heating load: 18,663 W
(Boundary conditions: outdoor temperature -14°C (7°F), indoor temperature 21°C (70°F))
The certification according to GEG2020 was done without controlled mechanical ventilation, but we still plan to install a central controlled mechanical ventilation system.
A few days ago, a heating contractor visited us who seemed very competent and provided a quote on site. He plans to install a Daikin Altherma 3 H HT BG14.
Another heating contractor, who has not yet visited the site, submitted a quote and plans to use a Vaillant Arotherm plus with a two-unit cascade VWL 75/6 A S2.
HB1 – the Daikin contractor – generally offers savings through DIY work, such as laying underfloor heating pipes, drainage pipes, etc.
HB2 – the Vaillant contractor – only allows DIY for laying the underfloor heating pipes; all other work is to be carried out by him.
HB1’s quote is around 50,000 gross including the Daikin heat pump, plumbing (fresh water + wastewater) and so far _without_ controlled mechanical ventilation.
HB2’s quote is about 54,000 gross including the Vaillant heat pump, plumbing (fresh water + wastewater), and controlled mechanical ventilation (Paul Novus 300).
HB2 initially offered a Vaillant 55/6 model (4,000 less expensive), but after a follow-up, corrected the offer to the two-unit cascade 75/6. At first, it seemed strange to me that a significantly smaller heat pump would suffice compared to HB1’s offer. After inquiry, he explained that he calculated with a Vaillant tool and therefore came up with the above two-unit cascade 75/6.
My questions:
- How do you assess the sizing of the heat pump?
- Are there any advantages or disadvantages or known issues with the respective Daikin/Vaillant models?
- How do you generally assess the prices?
- Do you have any other recommendations?
I look forward to your feedback – if you need further information, I’m happy to share 🙂
We are currently building our single-family home, and the shell is basically completed. Now I am working on the quotes for heating/plumbing and would appreciate your assessment regarding the sizing of the heat pump. Due to the KfW funding stop in 2022, we decided not to aim for KfW40 or 55 standards, allowing us more flexibility for DIY work and so on.
The house has three floors and is built on a slope, with the basement partly underground at the rear and exposed on the front side. The heated area in the basement consists of approximately 30m² (323 sq ft) of living space plus stairwell/hall/entrance area, while the remaining areas are unheated: technical room (14m² (150 sq ft)) and an unheated garage (62m² (668 sq ft)).
The ground floor and upper floor are fully heated.
The heated area is around 190–200m² (2045–2153 sq ft).
We have an energy certificate according to GEG2020 with the following data:
- Heated building volume: 876m³ (30,925 cu ft)
- Envelope surface area: 576m² (6,200 sq ft)
- Heated air volume: 666m³ (23,518 cu ft)
- Window area: 66m² (710 sq ft)
- Usable floor area according to the Building Energy Act (Gebäudeenergiegesetz): 280m² (3,014 sq ft)
- Primary energy demand: 44.41 kWh/(m²·a)
- Transmission heat loss coefficient: 0.345 W/(m²·K)
- Transmission heat loss: 6,951 W
- Ventilation heat loss: 5,546 W
- Additional heating load: 6,167 W
- Total heating load: 18,663 W
(Boundary conditions: outdoor temperature -14°C (7°F), indoor temperature 21°C (70°F))
The certification according to GEG2020 was done without controlled mechanical ventilation, but we still plan to install a central controlled mechanical ventilation system.
A few days ago, a heating contractor visited us who seemed very competent and provided a quote on site. He plans to install a Daikin Altherma 3 H HT BG14.
Another heating contractor, who has not yet visited the site, submitted a quote and plans to use a Vaillant Arotherm plus with a two-unit cascade VWL 75/6 A S2.
HB1 – the Daikin contractor – generally offers savings through DIY work, such as laying underfloor heating pipes, drainage pipes, etc.
HB2 – the Vaillant contractor – only allows DIY for laying the underfloor heating pipes; all other work is to be carried out by him.
HB1’s quote is around 50,000 gross including the Daikin heat pump, plumbing (fresh water + wastewater) and so far _without_ controlled mechanical ventilation.
HB2’s quote is about 54,000 gross including the Vaillant heat pump, plumbing (fresh water + wastewater), and controlled mechanical ventilation (Paul Novus 300).
HB2 initially offered a Vaillant 55/6 model (4,000 less expensive), but after a follow-up, corrected the offer to the two-unit cascade 75/6. At first, it seemed strange to me that a significantly smaller heat pump would suffice compared to HB1’s offer. After inquiry, he explained that he calculated with a Vaillant tool and therefore came up with the above two-unit cascade 75/6.
My questions:
- How do you assess the sizing of the heat pump?
- Are there any advantages or disadvantages or known issues with the respective Daikin/Vaillant models?
- How do you generally assess the prices?
- Do you have any other recommendations?
I look forward to your feedback – if you need further information, I’m happy to share 🙂
HB2 has only provided a total price for heat pump + fresh water + wastewater + underfloor heating (36k net).
HB1 is broken down a bit more: heat pump 19.4k + piping 2.5k + underfloor heating 7.5k + potable water 7.2k + wastewater 3.7k = 40.3k net.
In HB2, the installation of the underfloor heating is included as done by me.
In HB1, the installation by me still needs to be deducted.
HB1 is broken down a bit more: heat pump 19.4k + piping 2.5k + underfloor heating 7.5k + potable water 7.2k + wastewater 3.7k = 40.3k net.
In HB2, the installation of the underfloor heating is included as done by me.
In HB1, the installation by me still needs to be deducted.
R
RotorMotor10 Aug 2023 09:19Do you mean by "system with a Vaillant aroTHERM plus 2-unit cascade VWL 75/6 A" that two heat pumps are actually going to be installed?
This is how it is stated in the offer and in the results from the Vaillant software, which I received as a PDF... it seems that two heat pumps are operating in a cascade system.
If you search for the EAN (4024074893081) on Google, you will find offers that include two heat pumps. I believe the two units are stacked on top of each other?
If you search for the EAN (4024074893081) on Google, you will find offers that include two heat pumps. I believe the two units are stacked on top of each other?
K
KarstenausNRW10 Aug 2023 11:19I just calculated the heating load myself. The result is that a 7kW heat pump is sufficient (with a central controlled ventilation system for living spaces and 4 people in the household for heating/domestic hot water).
R
RotorMotor10 Aug 2023 11:24It’s hard to say what your actual heating load really is.
However, both quotes seem oversized to me.
We also have almost 200 m² (2,150 sq ft) of heated area, and our 75/6 ground source heat pump is completely oversized.
We have better insulation, and the natural air exchange rate is also a bit higher, but installing two units seems really excessive to me.
It also generates high costs for purchase and maintenance, noise, etc. The control system becomes more complicated as well...
It probably makes sense to invest in a proper heating load calculation.
There are good providers who can size both the heating system and the heating circuits.
How do you come up with such a high value?
However, both quotes seem oversized to me.
We also have almost 200 m² (2,150 sq ft) of heated area, and our 75/6 ground source heat pump is completely oversized.
We have better insulation, and the natural air exchange rate is also a bit higher, but installing two units seems really excessive to me.
It also generates high costs for purchase and maintenance, noise, etc. The control system becomes more complicated as well...
It probably makes sense to invest in a proper heating load calculation.
There are good providers who can size both the heating system and the heating circuits.
KarstenausNRW schrieb:
I just calculated the heating load myself. The result is that a 7 kW heat pump is sufficient (with central mechanical ventilation with heat recovery and 4 people in the household for heating/domestic hot water).
How do you come up with such a high value?
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