ᐅ New Construction KfW55 House – Heating System Design, Conflicting Information
Created on: 5 Dec 2020 13:15
D
DE_Haus
Hello 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 19:06
Wall heating in the bathroom is a great feature.
Otherwise, choose a system that qualifies for the BAFA subsidy, and make sure to submit the application by December at the latest. Who knows if there will still be such high support for air-to-water heat pumps next year... Of course, it could theoretically improve, but personally, I don’t believe that.
And as mentioned, make sure to prioritize a proper underfloor heating system.
Otherwise, choose a system that qualifies for the BAFA subsidy, and make sure to submit the application by December at the latest. Who knows if there will still be such high support for air-to-water heat pumps next year... Of course, it could theoretically improve, but personally, I don’t believe that.
And as mentioned, make sure to prioritize a proper underfloor heating system.
H
HilfeHilfe5 Dec 2020 20:35Ötzi Ötztaler schrieb:
What did he do to your heating system? Or was he in bed with your wife? :-p;) just incompetent... installed a heat pump that kept failing. We now have a new one.Hello everyone,
Thank you very much for all the responses.
From what I understand now, it doesn’t really matter which manufacturer we choose? The issue of noise emission is also very important to us!
But is there a technical explanation regarding the drinking water station? How are the ongoing costs? Higher or lower?
Furthermore, what is the technical reason why I shouldn’t use a heating buffer tank? As I understand it, normally water is stored in the buffer tank at a certain temperature and then pumped into the heating circuit in portions? This way, the air-to-water heat pump doesn’t have to run continuously?!
Best regards
Thank you very much for all the responses.
From what I understand now, it doesn’t really matter which manufacturer we choose? The issue of noise emission is also very important to us!
But is there a technical explanation regarding the drinking water station? How are the ongoing costs? Higher or lower?
Furthermore, what is the technical reason why I shouldn’t use a heating buffer tank? As I understand it, normally water is stored in the buffer tank at a certain temperature and then pumped into the heating circuit in portions? This way, the air-to-water heat pump doesn’t have to run continuously?!
Best regards
N
nordanney5 Dec 2020 21:54DE_Haus schrieb:
But is there also a technical explanation regarding the drinking water station? How about the ongoing costs? Higher/lower? See technical details in #11.
There are practically no ongoing costs. It has major advantages in terms of always having fresh water, but requires a higher initial investment.
DE_Haus schrieb:
Furthermore, what is the technical explanation for why I shouldn’t use a heating buffer tank? Because you already have the biggest buffer—the screed. Why install a small buffer that then feeds a large buffer? That only results in efficiency loss.
The heat pump will not run differently or more often—just more efficiently.
T
T_im_Norden5 Dec 2020 22:39The heat pump should run as long as possible at the lowest possible temperatures.
What benefit would a water buffer tank bring you?
To store heat, significantly more heat would have to be supplied than the actual flow temperature requires.
For example, if a flow temperature of 25°C (77°F) were sufficient, the buffer tank would need to be operated at around 30°C (86°F) just to compensate for the heat losses occurring in the tank.
So you lose 5°C (9°F) of heat that you would actually need for heating.
If you had heated continuously at 25°C (77°F), more heat would have been delivered into the house using less energy.
The main reason for these buffers is usually that the heating contractor or manufacturer wants to ensure that there is enough heat available for the defrost cycle of the air-to-water heat pump.
What benefit would a water buffer tank bring you?
To store heat, significantly more heat would have to be supplied than the actual flow temperature requires.
For example, if a flow temperature of 25°C (77°F) were sufficient, the buffer tank would need to be operated at around 30°C (86°F) just to compensate for the heat losses occurring in the tank.
So you lose 5°C (9°F) of heat that you would actually need for heating.
If you had heated continuously at 25°C (77°F), more heat would have been delivered into the house using less energy.
The main reason for these buffers is usually that the heating contractor or manufacturer wants to ensure that there is enough heat available for the defrost cycle of the air-to-water heat pump.
T_im_Norden schrieb:
The main reason for these buffers is usually that the house builders or manufacturers want to ensure there is enough heat available for the defrost cycle of the air-to-water heat pump. Okay, thanks for the information. But do house builders actually install systems without a heating buffer? If it’s about ensuring safety for the defrost cycle? I assume most house builders have their reasons. But of course, your explanation about the pipes in the screed acting as a buffer and that the heat goes directly into the flow instead of first into the buffer—potentially avoiding heat loss—makes sense.
Regarding the prices mentioned in my previous question in post #1, are these realistic or is there still room for savings?
Best regards
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