ᐅ New Construction KfW55 House – Heating System Design, Conflicting Information
Created on: 5 Dec 2020 13:15
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DE_HausHello everyone,
I’ve been following the discussions here for a few days and decided to register today to share my current situation. My wife and I are planning our new build; the construction documents were submitted six weeks ago, and we are now waiting for the building permit/planning permission.
Currently, our plan is to work with an architect rather than a general contractor, so we have free choice among various heating and plumbing companies.
House details:
KFW55 standard
Flat roof, cubic design
Living area: 190 m² (including 2.5 m² (1 inch) balcony) so the actual living area is 187.5 m². The basement is 60.67 m², which includes 16.6 m² for technical rooms. Therefore, I would like to heat 187.5 + 34.99 m² (basement excluding technical rooms) = 222.5 m².
The thermal insulation certificate is currently being prepared, but an initial estimate of the heating demand has already been provided.
According to the KFW consultant and the first heating system quote, a Viessmann Vitocal 200-S AWB-E AC D09 would be sufficient to heat adequately at a 35°C (95°F) supply temperature, achieving an annual performance factor above 4.5 to qualify for subsidies. I have obtained not just one but several quotes to find the best offer with the same specifications. However, I’m running into a “medium-sized” problem here.
Statements from companies:
Each heating and plumbing company gives different opinions: “Viessmann is great, and we only work with that brand,” “Ochsner is the best choice,” “Weishaupt is top-notch quality,” and “Heliotherm is the secret favorite for air-to-water heat pumps.” Even worse, everyone thinks their technical solution is the best.
Other statements from the heating and plumbing companies include:
“The heating buffer tank ‘must be at least 300 liters (79 gallons),’”
“A buffer tank that is too large is not good,”
“A fresh water station is absolutely necessary to prevent legionella,”
“A fresh water station only makes sense in multi-family buildings,”
“Domestic hot water storage must be at least 300 liters (79 gallons),”
“You need an electric backup heater in the bathroom,”
“A backup heater is not necessary.”
By now, I’m more confused than at the beginning and don’t know what to believe anymore. However, most agreed on one point and offered an air-to-water heat pump with similar specifications.
This question has probably been asked hundreds of times and cannot be answered definitively since every system has its pros and cons. But which manufacturer currently stands out, offering units with low failure rates, good service, and high efficiency?
We want to install the heating unit outside the house and have already designated a suitable area, but it must comply with the required sound pressure limits for night operation.
We have a total of 5 rooms on the ground floor (bathroom, office, living/dining area, foyer, and a small pantry). We plan to have 6 or 7 heating circuits here: 1 for the bathroom, 1 for the office, 3 for the living/dining area, and 1 or 2 for the foyer including the stairwell.
On the upper floor, there are 7 rooms (hallway, child’s room 1, child’s room 2, second bathroom, utility room, main bathroom, master bedroom including wardrobe). We intend one heating circuit per room.
In the basement, there are 4 rooms (hallway, storage 1, storage 2, and technical room). We plan 3 heating circuits here as we will not heat the technical room.
Heating system quotes:
Weishaupt WWP LB 12-A R
Viessmann Vitocal 200-S AWB-E AC D09
Ochsner AIR Eagle 414 C11B G1-1
Heliotherm HP12L/10L-WEB (pending final calculation)
What is really necessary for the other components and the size of the storage tanks?
Hot water storage tank size?
Heating buffer tank size?
Fresh water station?
Pipe spacing for underfloor heating? 10 cm (4 inches) in the bathroom and 15 cm (6 inches) in other rooms?
Backup heater in the bathroom? We want a heater there anyway to dry towels, so that is no big issue for us.
Finally, regarding the costs... these are ONLY for the heating system including underfloor heating, insulation, and commissioning. Water pipes and drainage are NOT included.
1.) Weishaupt WWP LB 12-A R with 100 L (26 gallons) heating buffer tank, 300 L (79 gallons) domestic hot water storage tank, no fresh water station, with circulation pump, including 3 electric wall heaters, air and dirt separators, plus insulation and underfloor heating: 34,500 € net
2.) Company 1 offer: Viessmann Vitocal 200-S AWB-E AC D09, VitoCell 100W 200 L (53 gallons) heating buffer, Vitocell 100W 300 L (79 gallons) domestic hot water tank, no fresh water station, with circulation pump, including 3 electric wall heaters, dirt separator but no air separator, plus insulation and underfloor heating: 29,300 € net
3.) Ochsner AIR Eagle 414 C11B G1-1, Ochsner 320 L (85 gallons) domestic hot water tank, 200 L (53 gallons) separation tank PU200, no fresh water station, with circulation pump, including 3 electric wall heaters, dirt separator but no air separator, plus insulation and underfloor heating: 38,300 € net
4.) Company 2 offer: Viessmann Vitocal 200-S AWB-E AC D09, VitoCell 120E with 350 L (92 gallons) domestic hot water tank and 250 L (66 gallons) heating buffer, VitoTrans 353 fresh water station, with circulation pump, no 3 electric wall heaters, Viessmann dirt and air separators, plus insulation and underfloor heating: 29,800 € net
5.) Heliotherm offer pending.
I would appreciate any tips or advice on what is really necessary to heat our house because I am now totally overwhelmed… prices also vary significantly.
Thank you very much and have a nice St. Nicholas Day weekend!
Greetings from Hesse =)
I’ve been following the discussions here for a few days and decided to register today to share my current situation. My wife and I are planning our new build; the construction documents were submitted six weeks ago, and we are now waiting for the building permit/planning permission.
Currently, our plan is to work with an architect rather than a general contractor, so we have free choice among various heating and plumbing companies.
House details:
KFW55 standard
Flat roof, cubic design
Living area: 190 m² (including 2.5 m² (1 inch) balcony) so the actual living area is 187.5 m². The basement is 60.67 m², which includes 16.6 m² for technical rooms. Therefore, I would like to heat 187.5 + 34.99 m² (basement excluding technical rooms) = 222.5 m².
The thermal insulation certificate is currently being prepared, but an initial estimate of the heating demand has already been provided.
According to the KFW consultant and the first heating system quote, a Viessmann Vitocal 200-S AWB-E AC D09 would be sufficient to heat adequately at a 35°C (95°F) supply temperature, achieving an annual performance factor above 4.5 to qualify for subsidies. I have obtained not just one but several quotes to find the best offer with the same specifications. However, I’m running into a “medium-sized” problem here.
Statements from companies:
Each heating and plumbing company gives different opinions: “Viessmann is great, and we only work with that brand,” “Ochsner is the best choice,” “Weishaupt is top-notch quality,” and “Heliotherm is the secret favorite for air-to-water heat pumps.” Even worse, everyone thinks their technical solution is the best.
Other statements from the heating and plumbing companies include:
“The heating buffer tank ‘must be at least 300 liters (79 gallons),’”
“A buffer tank that is too large is not good,”
“A fresh water station is absolutely necessary to prevent legionella,”
“A fresh water station only makes sense in multi-family buildings,”
“Domestic hot water storage must be at least 300 liters (79 gallons),”
“You need an electric backup heater in the bathroom,”
“A backup heater is not necessary.”
By now, I’m more confused than at the beginning and don’t know what to believe anymore. However, most agreed on one point and offered an air-to-water heat pump with similar specifications.
This question has probably been asked hundreds of times and cannot be answered definitively since every system has its pros and cons. But which manufacturer currently stands out, offering units with low failure rates, good service, and high efficiency?
We want to install the heating unit outside the house and have already designated a suitable area, but it must comply with the required sound pressure limits for night operation.
We have a total of 5 rooms on the ground floor (bathroom, office, living/dining area, foyer, and a small pantry). We plan to have 6 or 7 heating circuits here: 1 for the bathroom, 1 for the office, 3 for the living/dining area, and 1 or 2 for the foyer including the stairwell.
On the upper floor, there are 7 rooms (hallway, child’s room 1, child’s room 2, second bathroom, utility room, main bathroom, master bedroom including wardrobe). We intend one heating circuit per room.
In the basement, there are 4 rooms (hallway, storage 1, storage 2, and technical room). We plan 3 heating circuits here as we will not heat the technical room.
Heating system quotes:
Weishaupt WWP LB 12-A R
Viessmann Vitocal 200-S AWB-E AC D09
Ochsner AIR Eagle 414 C11B G1-1
Heliotherm HP12L/10L-WEB (pending final calculation)
What is really necessary for the other components and the size of the storage tanks?
Hot water storage tank size?
Heating buffer tank size?
Fresh water station?
Pipe spacing for underfloor heating? 10 cm (4 inches) in the bathroom and 15 cm (6 inches) in other rooms?
Backup heater in the bathroom? We want a heater there anyway to dry towels, so that is no big issue for us.
Finally, regarding the costs... these are ONLY for the heating system including underfloor heating, insulation, and commissioning. Water pipes and drainage are NOT included.
1.) Weishaupt WWP LB 12-A R with 100 L (26 gallons) heating buffer tank, 300 L (79 gallons) domestic hot water storage tank, no fresh water station, with circulation pump, including 3 electric wall heaters, air and dirt separators, plus insulation and underfloor heating: 34,500 € net
2.) Company 1 offer: Viessmann Vitocal 200-S AWB-E AC D09, VitoCell 100W 200 L (53 gallons) heating buffer, Vitocell 100W 300 L (79 gallons) domestic hot water tank, no fresh water station, with circulation pump, including 3 electric wall heaters, dirt separator but no air separator, plus insulation and underfloor heating: 29,300 € net
3.) Ochsner AIR Eagle 414 C11B G1-1, Ochsner 320 L (85 gallons) domestic hot water tank, 200 L (53 gallons) separation tank PU200, no fresh water station, with circulation pump, including 3 electric wall heaters, dirt separator but no air separator, plus insulation and underfloor heating: 38,300 € net
4.) Company 2 offer: Viessmann Vitocal 200-S AWB-E AC D09, VitoCell 120E with 350 L (92 gallons) domestic hot water tank and 250 L (66 gallons) heating buffer, VitoTrans 353 fresh water station, with circulation pump, no 3 electric wall heaters, Viessmann dirt and air separators, plus insulation and underfloor heating: 29,800 € net
5.) Heliotherm offer pending.
I would appreciate any tips or advice on what is really necessary to heat our house because I am now totally overwhelmed… prices also vary significantly.
Thank you very much and have a nice St. Nicholas Day weekend!
Greetings from Hesse =)
Ötzi Ötztaler5 Dec 2020 13:31
Ochsner would be my last choice.
DE_Haus schrieb:
What is really necessary for the other components and the size of the storage tanks? Domestic hot water tank size? 300L (80 gallons) should be sufficient for a four-person household of this size.
Heating buffer tank size? Since there is a heat pump and underfloor heating, no buffer tank is needed.
Potable water station? This is a matter of preference; if the budget allows, yes, otherwise not necessary.
Floor heating pipe spacing? Bathroom 10cm (4 inches) and other rooms 15cm (6 inches)? Additional heating in the bathroom? Pipe spacing should not be chosen arbitrarily based on preferences or "what we always do." It should be determined by the heat loss of the room and its intended use. Window glazing and fixed furniture also play a role. Especially for the bathroom(s), detailed calculations per square meter are advisable, possibly including partial wall heating. If you still want a towel radiator, consider an electric version, as its use is likely to be occasional.
Which heat pump ultimately supplies the energy is more or less secondary. It just needs to be appropriately sized for the house – not too weak, but also not oversized. It is much more important that the installer is familiar with the equipment and technology to avoid becoming a test subject.
Ochsner would not necessarily be my first choice, based on moderate experiences my parents had with Ochsner’s service when problems arose. During the construction phase, I had issues with Waterkotte, which is why I ended up switching to Alpha Innotec at short notice, but only because the new heating installer preferred to offer Alpha Innotec. My advice: don’t force an installer to use any brand other than their preferred one, it usually doesn’t work out.
I would focus your decision on which company can most convincingly demonstrate that they will install the system to achieve the lowest possible supply temperature. This involves proper system design and a willingness to use tight pipe spacing according to the calculations.
You will benefit more from this in the long run than from saving around 2,000 EUR on the initial quote. Which unit is ultimately installed is less important, as long as the customer service is good. On paper, almost all current heat pumps perform well; the “art” of the installer lies mainly in operating them within their efficient working range. That’s what separates the good ones from the bad. It will certainly provide warmth regardless.
I would focus your decision on which company can most convincingly demonstrate that they will install the system to achieve the lowest possible supply temperature. This involves proper system design and a willingness to use tight pipe spacing according to the calculations.
You will benefit more from this in the long run than from saving around 2,000 EUR on the initial quote. Which unit is ultimately installed is less important, as long as the customer service is good. On paper, almost all current heat pumps perform well; the “art” of the installer lies mainly in operating them within their efficient working range. That’s what separates the good ones from the bad. It will certainly provide warmth regardless.
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