ᐅ Hot water supply, tankless water heater (yes/no);

Hello Havejan,
you probably have a wooden house from Weberhaus, right? Were the interior walls already installed at the factory using drywall panels? Normally, these are not plastered but only skim-coated (with or without a painter’s fleece) and then wallpapered or painted directly.
We also have a heat recovery ventilation system (LWZ) in our house. All of your points were discussed in the consultation. It was even mentioned that after filling the bathtub completely, a second fill is not possible, but overall this heating system hardly causes any problems. 44 degrees Celsius (111°F) is more than enough for washing dishes! Do you want boiling water from your tap?
@ €uro: Havejan raised the issue of Legionella. Is this really relevant for a single-family house, considering that Legionella can settle in the pipes at temperatures below 60 degrees Celsius (140°F)? I naively assume, like Havejan, that you don’t have a pre-heating installation required by KfW.

Hello Wastl,

You probably have a timber frame house from Weberhaus, right? The interior walls there were factory-finished with drywall panels? These are usually not plastered but just skim-coated (with or without a painting fleece) and then wallpapered or painted directly.

Yes, we have a timber frame house with gypsum board. At least half of it has been removed and reinstalled. Normally, wallpapering is done, but we wanted a fine plaster finish inside. Since Weberhaus did not want or could not supply the paint (we had the “recipe”), we removed the plaster. Now Weberhaus says that the painting fleece is not part of the skim coat and was the responsibility of our painter. When we asked whether the skim coating was finished enough for the painter to just sand and plaster, they refused to give a clear answer and hide behind saying that nothing is documented in writing.

We also have a ventilation and heat recovery system in our house. All your points were discussed during the consultation. It was even pointed out that after filling the bathtub once, there wouldn’t be enough warm water for a second time, but this heating system doesn’t really cause problems.

We were not informed about that, nor about the water temperature. At the moment, the heating system does not cause any problems.

44 degrees Celsius (111°F) is plenty to wash dishes?! Do you want boiling water from your tap?

44 degrees Celsius (111°F) is enough for washing plates, but not for greasy pans or oven ceramics. When I fill our large ceramic sink, the water temperature drops to only 39 degrees Celsius (102°F). That is not enough, and certainly not enough to keep the pipes clean from soap and grease residues.

@ €uro: Havejan raised the issue of legionella. Is it really relevant in a single-family home that legionella bacteria can settle in the pipes if the temperature is below 60 degrees Celsius (140°F)? I naively assume that, like me, Havejan does not have a preheating installation required by KfW.

It is unlikely to have legionella if the water flows regularly through all pipes, but here in France, it is required by law that the water is heated weekly.

I am now at the point where I have given up on communicating with Weberhaus. Weberhaus refuses to act in a customer-friendly way and, as I said, hides behind the fact that certain things are not in writing. I am completely fed up with this company and will not recommend them to anyone. They claim to be customer-friendly, but their customer service is not even able to respond properly to emails or phone calls. I keep receiving letters by mail that take at least five days to arrive. I could go on much longer, but I no longer have the energy for it. Maybe I will share my experience in a separate topic here in the forum.

Havejan schrieb:
....It is not very likely to have Legionella if water is flowing through all the pipes, but here in France, it is mandatory by law to heat the water weekly....

The issue of Legionella is somewhat of a "gray area." They become critical mainly when present in lung-accessible areas (inhalation of water vapor or mist). In Germany, weekly heating of indirectly heated water tanks to above 60°C (140°F), followed by flushing of the supply lines to the taps, has proven effective. There are now new requirements (drinking water regulations), depending on whether the system is a small installation (single-family house, two-family house) or a large system. For the latter, an annual Legionella inspection is required for storage tank sizes of >= 400 liters (105 gallons) and water content <= 3 liters (0.8 gallons) between the outlet of the water heater and the withdrawal point.

The production of domestic hot water is not independent of the type of heat generator when heating and hot water preparation are to be operated alternatively by the same heat generator. Gas condensing boilers (natural gas!) are, if properly sized (manufacturer, equipment selection), today the "modulation champions" and can meet all requirements relatively well. Indirectly heated water tanks are still usually sensible in this context.

It looks quite different with heat pumps as heat generators. Especially in well to very well insulated buildings, the required capacity of the heat generator for heating operation is relatively low. For hot water, in bivalent or alternative operation, there is often a lack of necessary capacity for an indirectly heated hot water tank. This applies particularly to combined solutions often sold by general contractors. A solution here is "heat-pump-friendly" indirectly heated hot water tanks from external suppliers.

Simply oversizing the capacity from the perspective of hot water production usually leads to a significant loss of efficiency for heating operation and thus overall! Additionally, the heat pump will have a short service life.

As an alternative, instant water heaters (fresh water stations) should be considered. In these systems, it is not the potable water stored as in indirectly heated tanks, but the heating water! However, the additional cost is not insignificant. As always, this must be assessed on a case-by-case basis. With high flow rate requirements (e.g., rain showers), instant water heaters often fail if improperly designed!

Best regards.

Conclusion: Domestic hot water production requires just as detailed and precise system planning and sizing (basic assessment) as heating operation, if an overall economical solution is desired!

Hello Jan,

Havejan schrieb:

I have now reached the point where I have broken off communication with Weberhaus. Weberhaus refuses to be customer-friendly and, as mentioned, hides behind the fact that certain things are not documented on paper. I am completely done with this company and will not recommend them to anyone. They call themselves customer-friendly, but their customer service is not even capable of responding properly to emails or phone calls. I keep receiving letters by mail that take at least 5 days to arrive. I could go on for a long time, but I don’t want to anymore. Maybe I will eventually list my experiences in a separate thread here in the forum.

Regarding your issues with your provider, I would strongly recommend consulting a lawyer you trust and discussing the defects of the house with them. There are times — unpleasant as they may be — when lawyers can quickly and often straightforwardly provide solutions. Your provider will also want to avoid bad publicity and will address your problem once a lawyer becomes involved.

I wish you the best of luck!