Is the hot water tank sufficient?

Perhaps it should be mentioned that the heating system from Vaillant is a complete system. It is called the geoTHERM heat pump system. As far as I understand, it is a combination unit that on one hand produces low-temperature heating water and additionally integrates a 175L hot water storage tank, which can then be heated up to a maximum of 62°C with a 6KW electric heating rod. The latter, however, is pointless if one can manage with 175L. Then probably 44°C or something similar would suffice. The question is therefore, how far can you get with 175L of hot water and how fast is the heating rod?

Hello,

...this is about the design of the heat pump and its favorable operating range.
The main job of the heat pump is space heating....

That is not necessarily the case. For an energy saving ordinance standard this may apply, but not for a PH. For this reason, a basic determination (performance, energy) for heating and hot water is also required.

... If the heat pump can also manage it directly, then with such a poor efficiency that the electricity costs incurred are in a very unfavorable ratio to the achieved performance...

Therefore, hot water tanks supplied by heat pumps are designed somewhat differently than, for example, those supplied by gas condensing boilers. With good planning, an electric heating element is not required for normal operation.

...Then the higher investment costs for heat pumps compared to, for example, gas condensing boilers would no longer be amortized, which is already difficult enough in reality...

Noticeably higher investment costs should only apply to ground source heat pumps with vertical probes. For air heat pumps, the investment costs are comparable to gas condensing boilers, if you do not forget their connection costs.

...Better more storage, optimized for this type of use, at lower temperatures, than a standard tank with high temperatures.

That is correct.

Best regards.

The question is therefore, how far can you get with 175L of hot water...?

That will probably be different for everyone, but as a guideline you can look up your last water bill and calculate the average total consumption per day. That will include cold water as well, but at least you have a rough idea.

That may be different for everyone, but as a guideline, you can look up your last water bill and calculate the average total consumption per day. Although that also includes the cold water, at least you have a rough idea.

If Sunday is a big bath day for all family members, then the average is meaningless.

Hello everyone, I am bringing up the thread again because I didn't want to open a new one just for a question. For our 148 sqm city villa, the construction company is planning a geothermal heat pump Weishaupt wwp S6 IDT with an integrated 170-liter hot water tank and buffer storage. Is the 170 liters sufficient for a 4-person household or could that be tight?

Dear ZePetrator

We had asked ourselves this question too... and discussed it with friends and acquaintances.

As an answer, there is an extremely wide range.

You can estimate a solution based on key figures (a) and technical boundary conditions/comfort requirements (b) & coordinate with your trusted TGA specialist.

a) Key figures
- Water bill from the previous year without garden water
set about 30% as hot water demand
=> Water volume per day

- Energy consumption / hot water from the previous year
=> Energy amount for heating per day

- It gets a bit hectic in the morning with 4 people if the kids at a certain age want to shower longer than 15 minutes ... 2 bathrooms available??
=> Peak load in liters/minute that must be delivered

- Bathtub planned??
depending on the design, that's 100 to 250 liters at 42 degrees that must be delivered quickly

b) Comfort
- Should there be a hot water circulation pump
xx seconds until hot water flows from the tap on the 3rd floor??
=> Plan for idle losses

- How hot does the "cook" want the water from the kitchen tap (we gave this up because it is too expensive, a small kettle is much cheaper in operation)
with many small draw-offs, about 80% cold water is "wasted" before really usable hot water arrives in the kitchen.

- Should the water for showering come almost ready to use from the tap (about 35 degrees), or should the mixer/thermostat mix cold water (see comment from the other post)

- Attention when selecting the control: in summer operation, a lot of heat can evaporate unused with some systems/controls.

- The 170L storage tank does not deliver 170L of hot water!!
With many small amounts taken, the warm residual water mixes with the incoming cold water
Result: mixing temperature for the next draw-off
and not the outlet temperature BEFORE the draw-off.
Even sophisticated stratified tanks have this effect, only it is significantly less here.
The max. draw-off quantity is measured in one go during withdrawal; but this does not correspond to private practice throughout the day.

I hope this brainstorming stimulates your discussion in the family and with the TGA planner and that you feel comfortable later with the hot water supply.

For us (2 adults, 3 teenagers), it worked great after a little getting used to. Our neighbors have about double the energy consumption for hot water... and are happy with it too...