ᐅ Ground Source Heat Pump – What to Watch for When Reviewing a Quote (Single-Family Home, New Build, KfW 70 Standard)
Created on: 31 Jan 2014 08:21
L
Lacos
Hello everyone,
We are planning to build with a general contractor (single-family house, about 136 sqm (1463 sq ft), gable roof, ≤KFW70) and would like to enter the final negotiations with the last 2 or 3 points.
The construction descriptions each list ground source heat pumps (brand name + buffer tank), but without much detail. I would like to ask for your recommendations in this area.
Since brand names probably shouldn’t be mentioned here:
A brine-to-water ground source heat pump with a COP of 4.7 is specified (integrated domestic hot water tank of 185L (49 gallons)). Additionally, a buffer tank, probably between 200 - 300L (53 - 79 gallons), is planned.
1. Is this combination reasonable?
2. What should generally be considered with heat pumps? I definitely want to install a heat meter and a separate electricity meter. What else should be taken into account?
3. Which combination do you consider the most practical (e.g., size of the buffer tank, etc.) for a household of two people (both working, possibly one child in a few years)?
Thank you very much in advance,
Lacos
We are planning to build with a general contractor (single-family house, about 136 sqm (1463 sq ft), gable roof, ≤KFW70) and would like to enter the final negotiations with the last 2 or 3 points.
The construction descriptions each list ground source heat pumps (brand name + buffer tank), but without much detail. I would like to ask for your recommendations in this area.
Since brand names probably shouldn’t be mentioned here:
A brine-to-water ground source heat pump with a COP of 4.7 is specified (integrated domestic hot water tank of 185L (49 gallons)). Additionally, a buffer tank, probably between 200 - 300L (53 - 79 gallons), is planned.
1. Is this combination reasonable?
2. What should generally be considered with heat pumps? I definitely want to install a heat meter and a separate electricity meter. What else should be taken into account?
3. Which combination do you consider the most practical (e.g., size of the buffer tank, etc.) for a household of two people (both working, possibly one child in a few years)?
Thank you very much in advance,
Lacos
Hello,
Similarly, the heating system must be adequately sized (heating load, room heating requirements, heat emission surfaces, hydraulics)!
The size of the domestic hot water storage depends, in alternative or bivalent systems with a brine heat pump (prioritizing hot water), on its performance and the user’s load profile!
Best regards
Lacos schrieb:It could be, but it depends on the specific data from the initial assessment. With heat pumps, the capacity of the heat source is always crucial. This must be sized according to the actual demand (flow rate, energy) for heating and domestic hot water. Undersizing usually leads to excessive costs!
...
1. Is this combination sensible? ...
Similarly, the heating system must be adequately sized (heating load, room heating requirements, heat emission surfaces, hydraulics)!
Lacos schrieb:For well-designed systems, a buffer tank is generally not necessary on the heating side!
...
3. Which combination would you consider the most practical (e.g., volume of the buffer tank, etc.)...
The size of the domestic hot water storage depends, in alternative or bivalent systems with a brine heat pump (prioritizing hot water), on its performance and the user’s load profile!
Best regards
B
Bauher10102 Feb 2014 09:02Who can I ask to have my heating system checked by my general contractor before installation?
I just want to make sure that nothing faulty gets installed. Whether with or without a buffer tank, …
I just want to make sure that nothing faulty gets installed. Whether with or without a buffer tank, …
Bauher1010 schrieb:
Who can I ask if I want my heating system to be checked by my construction supervisor before installation?... You are welcome to contact me! Best regards.
Hello,
€uro is right – with well-designed systems, no buffer tank is needed on the heating side. In your case, for a typical single-family house, this should be possible.
A 185-liter (49-gallon) domestic hot water tank might be too small. How many people are in your household?
We have a 250-liter (66-gallon) tank, and it can just about handle showers for 4 people – but not 10 minutes each…
With a smaller tank, the heat pump would have to reheat the hot water more often.
For us, 250 liters (66 gallons) is sufficient to heat the water once a day.
Best regards
€uro is right – with well-designed systems, no buffer tank is needed on the heating side. In your case, for a typical single-family house, this should be possible.
A 185-liter (49-gallon) domestic hot water tank might be too small. How many people are in your household?
We have a 250-liter (66-gallon) tank, and it can just about handle showers for 4 people – but not 10 minutes each…
With a smaller tank, the heat pump would have to reheat the hot water more often.
For us, 250 liters (66 gallons) is sufficient to heat the water once a day.
Best regards
Before focusing on the heat pump, please first review the offer for the underfloor heating system. A crucial factor for the "success" of your heat pump is minimizing the spacing between the heating pipes. A maximum of 12 cm (5 inches), preferably 10 cm (4 inches) or less. House builders often try to save costs here. The smaller the spacing, the lower your flow temperature, and the better the efficiency of the heat pump.
A brine-ground-source heat pump with a COP of 4.7 (integrated hot water tank of 185 L (49 gallons)) is planned.
The stated COP is theoretical because it primarily depends on the installed heating system, brine, and peripheral components. The difference between heat pump types is likely less significant.
185 liters (49 gallons) of hot water is quite limited. 185 liters does not mean you have 185 liters of hot water available. As hot water is drawn off, cold water continuously replaces it, so once you have used about 80 liters (21 gallons), the temperature noticeably drops. I think 300 liters (79 gallons) should be the minimum, especially if you want a larger bathtub.
Additionally, a buffer tank, probably between 200 - 300 L (53 - 79 gallons), is planned.
This is often installed by heating contractors as a safety margin and to cover up potential mistakes. In terms of effectiveness and energy consumption, it is generally unnecessary. If you expect your heating system to be installed so that you only need to adjust the room thermostat, a buffer tank might be needed. However, if you are willing to engage more deeply in the system and adjust settings and parameters repeatedly during the first year, you can do without the buffer tank and benefit from lower consumption.
2. What general points should be considered regarding heat pumps? I would definitely have a heat meter and a separate electricity meter installed. What else should be considered?
A heat meter is not strictly necessary but very helpful for analysis purposes. You will likely receive a separate electricity meter anyway, as many utility providers offer special heat pump tariffs. Based on extremely poor experiences, I would choose the manufacturer primarily based on their customer service.
A brine-ground-source heat pump with a COP of 4.7 (integrated hot water tank of 185 L (49 gallons)) is planned.
The stated COP is theoretical because it primarily depends on the installed heating system, brine, and peripheral components. The difference between heat pump types is likely less significant.
185 liters (49 gallons) of hot water is quite limited. 185 liters does not mean you have 185 liters of hot water available. As hot water is drawn off, cold water continuously replaces it, so once you have used about 80 liters (21 gallons), the temperature noticeably drops. I think 300 liters (79 gallons) should be the minimum, especially if you want a larger bathtub.
Additionally, a buffer tank, probably between 200 - 300 L (53 - 79 gallons), is planned.
This is often installed by heating contractors as a safety margin and to cover up potential mistakes. In terms of effectiveness and energy consumption, it is generally unnecessary. If you expect your heating system to be installed so that you only need to adjust the room thermostat, a buffer tank might be needed. However, if you are willing to engage more deeply in the system and adjust settings and parameters repeatedly during the first year, you can do without the buffer tank and benefit from lower consumption.
2. What general points should be considered regarding heat pumps? I would definitely have a heat meter and a separate electricity meter installed. What else should be considered?
A heat meter is not strictly necessary but very helpful for analysis purposes. You will likely receive a separate electricity meter anyway, as many utility providers offer special heat pump tariffs. Based on extremely poor experiences, I would choose the manufacturer primarily based on their customer service.
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