Selection of heating system, gas condensing boiler + solar, or air heat pump

Hello dear community,

we are stuck with our decision regarding the choice of heating system. No matter how many people, friends, and experts we ask, we receive just as many different answers.

We cannot decide between a gas condensing boiler with solar support or an air heat pump. A ground source heat pump is not an option due to cost reasons and a water catchment area.

The architect has started planning and so far we were leaning towards the gas boiler, but the longer we think and ask around, the more uncertain we become. Originally, we wanted to move away from gas and oil, but the purchase price makes us reconsider.

Here are the facts:

[*]Winkelbungalow with ~130 sqm living space
[*]no basement
[*]no expandable roof
[*]underfloor heating
[*]possibly hot water connection for washing machine and dishwasher
[*]mix of double and triple glazing

What would you do in our case?

We have strong doubts about the costs during such harsh winter days.

Can you provide us with useful figures? Which combination would be good? Which would be the most cost-effective per year? I don't really trust all the salespeople.

Best regards

Hello,

...What would you do in our case?..

These are frequently asked questions. Just use the search function.

Without knowing the actual demand (power, energy), this will be a murky look into the crystal ball. Solar thermal systems hardly make sense in a single-family house, so if gas condensing boiler, then with improved insulation (15% rule).

...I don't really trust all these salespeople.

That is quite justified. Would you trust posts from anonymous authors instead?

Best regards

...We do not know the consumption yet, the architect is currently working on the planning.

The consumption only results in connection with the technical solution. Primarily, it is the demand.

...The bricks will be 24 cm Poroton bricks with 140mm insulation. Maybe that makes the statement more meaningful.

Unfortunately not! If it were that simple, one could save oneself any elaborate calculation.

Best regards

Sorry, but how am I supposed to know the demand if I don't live in the house yet?! I can't provide more than just numbers, but I can say that there will be three of us. The experiences should not be tailored to my needs – I just want to hear good or bad experiences from other members. For example, which models are recommended and which are not. Or someone has had good or bad experiences with this or that type of heating.

regards

Sorry, but how am I supposed to know the demand if I don’t live in the house yet?!

That (should) be calculated beforehand, provided the building, the climate location, and the user behavior (e.g. desired room temperatures) are defined. Or do you just buy a car without knowing how high the consumption will be?

best regards

Hello Rene81,

Overall, the planning process for a house is an iterative process. In addition to your own wishes, the requirements due to the number, possibly also age/health condition of the users, the location conditions, external changes such as energy price developments, societal changes, as well as legal requirements, both building law and funding regulations, your own budget, etc., etc., your house ultimately develops. So far, those involved in such a process have been the builder and the architect, who can take into account a variety of the aforementioned framework conditions. As you have noticed, the matter is highly complex, and the objective for you and the other parties involved is to develop the optimum and avoid making any cardinal errors. In our opinion, an energy consultant should be involved in the planning phase, especially if the architect apparently cannot fully provide this or cannot cover this field. Probably for cost reasons, possibly because of the groundwater situation, but perhaps also due to the topic of "age-appropriate building," you have decided on a bungalow. By deciding that underfloor heating should be installed, the foundation has been laid that all possible heating variations can be implemented. The goal of energy consulting, which can also be carried out by a correspondingly qualified heating engineer, should initially be to achieve a correspondingly high building physics standard of the building envelope, since windows, roof, and walls should have service lives of 25 – 40 years. Here, of course, the question arises as to why partly double and triple glazing is implemented, whereby it should be known that the quality of a window consists of the frame, glass, and installation. Currently, overall U-values of 0.95 should be installed here. Due to the high energy standard and the underfloor heating, heating systems with small capacities can be installed. For example, modern gas condensing units can adapt to the demand today (modulation) and are already available on the market with capacities around 2 kW. Information is available from the energy consultant, heating specialist, or Stiftung Warentest. Unfortunately, the last test of gas condensing units is from mid-2010 but should provide a valuable reference regarding the advantages and disadvantages of the systems.

Regards