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
L
Lacos
5 Feb 2014 07:49
Hi everyone,

Thanks again for all the helpful contributions. Is it allowed to discuss brands here (if there are two options to choose from), or is this not appreciated or permitted?
S
stefanh
5 Feb 2014 08:34
@Lacos: Have you had an energy consultation?

I can only share my current situation...
Over the weekend, I received several documents from my energy consultant, including his recommended system configuration:

Key Data:

  • KFW-70 house standard
  • Building envelope area: 756.45 m² (8,140 sq ft)
  • Building volume: 1,265.72 m³ (44,672 cu ft)
  • Heated air volume: 961.95 m³ (33,963 cu ft)
  • Usable floor area: 405.03 m² (4,360 sq ft)
  • Surface-to-volume ratio (A/V): 0.60 1/m (0.18 1/ft)
  • Window area: 49.26 m² (530 sq ft)
  • Currently a two-person household, planning for up to five people in the future

Excerpt from Chapter 7.1 System Description:
Heating

  • Generation: Central heat generation with ground-source (brine-to-water) heat pump (annual performance factor 4.4)
  • Storage: 450-liter (119 gallon) buffer tank for underfloor heating

Hot Water

  • Generation: Ground-source heat pump covering 41% of demand and solar domestic hot water heating covering 59%
  • Bivalent storage tank: 750 liters (198 gallons)

Consumers:

  • Kitchen sink
  • Dishwasher
  • 2 industrial sinks
  • 3 toilets
  • 4 washbasins
  • 2 showers
  • 1 bathtub
L
Lacos
5 Feb 2014 08:43
I have not had an energy consultation yet. We have not signed anything so far (but soon), so I wanted to get informed in advance.
S
stefanh
5 Feb 2014 09:02
I was glad to have the initial energy consultation since otherwise, there is no reference point at all.

Additionally, I was able to coordinate with the shell construction company to check whether the building materials used are suitable for KfW 70 standard (overall). I can also provide the heating engineer with a document to guide them, as I was not familiar with the different specifications (see key data).

Who will be preparing the KfW application / energy certificate for you?
M
Michalko
5 Feb 2014 12:30
It is best to have the system commissioned by the factory service team, as they know best how to operate their equipment.
L
Lacos
15 Feb 2014 06:47
Hello everyone,

The energy performance certificate will be prepared by the general contractor – we want to build a turnkey house.

Thank you very much for all the many comments!
Regarding the heat pump, this one has now been selected. It includes an integrated 200-liter (53-gallon) storage tank, and according to the general contractor, no buffer tank will be used for the underfloor heating.
What is also interesting about this heat pump, besides a cooling function, is the touch control and operation via PC / iPhone app (the heat pump has a Wi-Fi module ^^).

Lacos

Similar topics