Away from fossil fuels - House from 1999

The basement is insulated: The basement walls are made from the same material as the rest of the house, only that they stand in a tub made of waterproof concrete. I don’t find 3,000 liters (usually it’s between 2,500 and 2,700) particularly much for 300 square meters. Although I have to correctly mention that three basement rooms (unheated) don’t have windows but ventilation openings, which I close with a slider in winter. A lot will certainly escape there. I did it that way back then because right during my planning phase, two friendly companies in the same industry were broken into with brute force, and very expensive equipment was stored in those rooms. So I preferred not to have windows there. You can’t break my windows with reasonable effort, but some perpetrators are stupid enough not to realize that and then cause huge damage anyway.

But if it is fundamentally the case that the surface area of the radiators is too small, then the whole project won’t work anyway, because I don’t want to make deep interventions in the house. The rooms in the basement are also equipped with very elaborate acoustic wall and ceiling coverings, so you can’t just pull new pipes to the upper floors. On the other hand, the heating distributors are easily accessible on every floor. But still, you would at least have to tear out the entire screed (in several rooms there are wooden floorboards on beam installation instead) to then install the wall heating and subsequently renovate all rooms. That would be a major construction site for many months with horrendous noise, dirt, work, and cost effort. Maybe you could do that with a used house that you took over as a ruin, but certainly not with a house that is only about 20 years old.

It might actually be better to wait it out. I always have to see my house in connection with my parents’ house, which stands directly next door on the same property and is almost 100 years old. There, the old oil heating was replaced a few years ago with a new oil heating because my father is not a fan of changes. And since my house stands on his property, it is practically his house legally, so of course he has a say in such matters. Old people aren’t as resilient anymore, especially when it comes to major construction projects, so I must not overstrain them. Therefore, only solutions with manageable effort are possible. I am well aware that none of this will ever pay off, except if oil prices multiply many times over. But it’s also about the better feeling when you no longer burn oil.

You can also try working with very large low-temperature radiators. Otherwise, the bivalent option would also be possible. I estimate that up to 32/33 degrees flow temperature is acceptable in terms of cost.

1. Have the heating load calculation carried out (Heckmann) 2. Have the flow temperature calculated with the largest possible (33 mm) radiators 3. Buy and have the heat pump installed 4. Replace radiators 5. Be happy Photovoltaics and storage should be discussed elsewhere. Unfortunately, I can't say where because I have already been blocked for that. But if currently a maximum of 40 degrees flow temperature is sufficient, a heat pump will also work.

Replacing all radiators would be a comparatively small evil, and possible everywhere without problems for us. However, one must then come up with a solution for how to proceed when renovating a room and temporarily removing the radiators, since the 33-mm ones will be one third heavier.

How does one find an independent consultant in Berlin with whom one can discuss all this, and who then ultimately develops a concept that can be implemented by a heating engineer and a photovoltaic specialist? Would the SHK guild, for example, recommend someone (at least for the heating sector), or do they not do that?

Matthias

I would first look at where the oil is going.

Some of it certainly into the old heating system. Especially for hot water in summer, the efficiency of those things is abysmal. From the description of the project, I would also say that a heat pump should work without problems. You still have a good part of the winter left, so you can do the usual transition exercises: record daily average temperatures and oil consumption daily. Initially set the flow temperature on the heating system to 50° (I guess the 40° you mentioned was the current, not the maximum flow temperature) and keep all radiators fully open at all times. If it gets too warm, lower the flow temperature further until the minimum. Turn off night setback. And then tackle the project here again or in that other forum. Regarding photovoltaics: there is also a place where you can get good and neutral advice. In short: you can often economically install photovoltaics on "bad" roofs. And then you still have a decent garage. So I would definitely take that on at least once. Please leave out storage, they are currently about 4 times too expensive to be economical. High self-sufficiency helps you nothing if it costs more than buying in. In contrast to oil heating, you can at least produce about 25% of your heating energy yourself quite easily. Without contortions. So: nice project, get started!

Set the flow temperature on the heating system initially to 50° (I guess the 40° you mentioned was the current, not the maximum flow temperature) and keep all radiators fully open at all times. If it gets too warm, lower the flow temperature further down to the minimum. Night setback off.

Is this done only for testing or can I generally set it like this in an old building?