190l vs. 309l hot water storage tank for 4 people

  • Erstellt am 2022-04-20 08:06:54

Sinosch31

2022-04-20 08:06:54
  • #1
Good morning everyone!

For the construction of our single-family house (the shell is currently underway), we are currently awarding the heating and plumbing work. First of all, here are some key data about the building:

- 2 full floors, a total of approx. 180 m² (170 m² living space, 10 m² technical room)
- no basement
- gable roof
- KFW 55 EE (including air-to-water heat pump, photovoltaic system)
- it will be occupied by 2 adults and 1 child (later a total of 2 children)

Planned is an air-to-water heat pump in combination with a photovoltaic system as well as underfloor heating.

Supplier A offers the following for the air-to-water heat pump:
Brand Vaillant with a hot water tank of 190 liters and all necessary accessories + installation for 28,560.00 euros net.

Supplier B offers the following:
Brand Weishaupt with a hot water tank of 309 liters and all necessary accessories + installation for 22,628.20 euros net.

My question: Do you have experience with the size of the hot water tank? Supplier A says that 190 liters is sufficient for a 4-person household. It should be mentioned that we like to shower longer. So we are not necessarily the most economical in this regard.

Thank you in advance for your opinions/experiences.
 

Bauenaberwie

2022-04-20 08:10:03
  • #2
I would definitely tend towards the 300L storage. 2-3 good showers and 190L is gone. Especially since the 300L ones are also significantly cheaper….
 

Benutzer200

2022-04-20 08:52:18
  • #3
Provider A is wrong. Own experience with three children (and me as a part-time dad). When the three kids come back from the stable and shower (long hair requires a lot of water under the rain shower) the 300-liter tank is down to only 25-30 degrees. For me, only lukewarm water remains ;). Definitely install 300 liters.
 

Scout**

2022-04-20 13:34:40
  • #4

We only have 150 liters for 3 people and I like to shower for a long time. That has always been enough so far. Also for a full bath and then a short shower afterwards. But: we have a gas boiler that can refill the hot water tank with 15 kW power! Your heat pump, on the other hand, will have a significantly lower output depending on the water temperature.

If you fill a somewhat larger bathtub with 240 liters and the air-water heat pump even heats to 55°, you already need a 160-liter tank and 80 liters of cold water for 240 liters of bath water at 40 degrees. And the air-water heat pump will then only be able to slowly reheat the tank, probably only with about 3 to 5 kW at this temperature level, i.e. a thin trickle. By comparison: an electric instantaneous water heater typically has a power of 22 kW and can therefore supply a shower "in real time" (although not a rain shower with very high water volume).

With 190 liters you therefore only have reserves for one full bath or about 15 minutes of showering (15x16 liters/min water at 40°). Anyone who comes into the bathroom afterwards will therefore have either lukewarm water or has to wait for hours.

Or everyone just showers briefly.

309 liters thus offers significantly more reserves (i.e., a full bath plus 15 minutes of showering next door) at the cost of slightly higher standby losses.
 

Matthias45

2022-04-20 16:43:43
  • #5


I would also take the offer with the larger storage tank. Because heating the water with a heat pump does not happen as quickly as with a gas heating system.
If several people shower one after the other, there is enough warm water available.

Heating 200 liters can take 1 hour with an air-water heat pump.
 

ypg

2022-04-20 17:28:46
  • #6

Take the 300-liter tank!
It could get out of hand for you :) Annoying if the quality of life suffers because of it. In the old house, we had 80 liters: one would be doing the dishes while the other was lying in the 170 cm tub, covered only with warm water.
 

Similar topics
08.06.2017Photovoltaic system, using experiences like a heat pump?64
30.05.2016KfW55: Gas or air-water heat pump with/without photovoltaics17
21.06.2016Heat pump with photovoltaics vs gas and solar thermal52
10.07.2016Air-water heat pump with photovoltaics or pellet with solar25
03.01.2017Preparation for photovoltaic or solar thermal with air-water heat pump18
22.05.2017New build bungalow - air-water heat pump, photovoltaic and solar thermal?17
22.02.2018Air-water heat pump, water-based pellet stove, and photovoltaic system17
24.07.2019Energy Saving Ordinance 2016 or KFW 55 for bungalow with air-water heat pump & controlled residential ventilation, optional photovoltaic47
13.12.2019Gas with solar thermal or heat pump? And possibly photovoltaics?13
07.05.2020Collaboration of air-water heat pump, photovoltaic system and storage38
05.12.2020Gas with solar thermal? Or heat pump with photovoltaics? Consultation149
08.05.2020Heat pump + photovoltaic system with or without storage11
28.07.2020Photovoltaics and heat pump - meter confusion and cost issue12
06.10.2021Photovoltaic system / heat pump, do you have 2 meters?55
03.01.2022Electricity meter for heat pump in combination with BAFA and photovoltaic22
24.02.2022Photovoltaic system air-water heat pump - profitability single-family house KFW55EE95
25.03.2022Switching from gas to solar / photovoltaic with / without heat pump31
18.09.2023Optimization of heat pump LWD 70A with photovoltaics16
22.03.2024Should photovoltaic design be considered with the heat pump or not?20
04.03.2024Costs for heat pump and photovoltaic in 2024 in small old buildings20

Oben