Hello,
We have already been to several construction companies to get offers for our house construction, but they all suggested something different for the heating system.
This is not surprising at all. If you asked even more, X new variants would appear and the confusion would be complete!
The ultimate and universally valid heating system definitely does not exist! However, there is a particularly advantageous solution for every project. This must be found. The building, orientation, location, climate site, user behavior, etc. form a unit. Also, building services engineering (heating, hot water preparation, ventilation, etc.) must always be considered as a whole.
Without knowledge of your individual framework conditions, no objective recommendation can be given if it is to be meaningful and effective.
… The first construction company recommended a groundwater heat pump due to the high groundwater level.
Solely the height of the groundwater level alone is not a decision criterion for a groundwater heat pump! Due to the requirements for water quality, there are relatively few sites suitable for the effective use of a groundwater heat pump! Here too, the framework conditions (recharge, absorption wells; iron hydroxide clogging) would first have to be clarified. If the surroundings are correct, very good annual performance factors can be achieved.
… The second construction company recommended a conventional gas heating system.
That can be an option, but it is not said that this is actually the cheapest option for you. Here, most often estimates and guesses are made rather than calculations, which later proves to be very disadvantageous in operation.
… And the third company recommended an air-to-water heat pump with a ventilation system (heat recovery).
The above also applies here, first the framework conditions must be clarified! Air heat pumps have characteristic curves that oppose the actual demand (building load curve) most strongly! Therefore, they are mostly used bivalently, i.e., with an additional heating element at low outdoor temperatures. This means partial electric heating! Otherwise, they would be mercilessly oversized in main operation, which can lead to considerable problems. In addition, here another component, ventilation, is mentioned, making a real comparison impossible!
It should be clarified beforehand whether a ventilation system is even required/necessary or desired for comfort reasons! With heat recovery, efficiency values are mostly advertised that are rarely achieved in practical operation. Therefore, this investment should also be carefully checked in advance.
Nevertheless, air-to-water heat pumps, despite their lower annual performance factor compared to other heat pumps, can represent a good solution for individual cases, provided sufficient dimensioning! Here the energy expenditure for hot water preparation has a particularly large influence.
… And our insurance advisor (building financier), who is also a good friend of ours, said we should do underfloor heating with solar energy. Can underfloor heating be operated with just solar power, is that enough?
Where does the insurance advisor get his knowledge? He certainly does not have training in building services engineering! You don’t go to the baker for toothache!!!
Of course, for all offers in combination with underfloor heating, we also want to have a fireplace.
Again, a standard and general statement. Both underfloor heating and radiators or convectors each have advantages and disadvantages. Underfloor heating and radiators are slow, so heating on demand is hardly possible; i.e., heating usually has to be continuous! The fireplace is primarily responsible for the experience of “fire”! Sustainable saving effects in combination with underfloor heating will hardly be possible because it cannot adequately react to the additional heat source. Radiators are much better suited for this. Their quick control behavior allows heating "ad libitum." External heat sources (fireplace) can be used much more effectively. This can result in significant savings effects depending on user behavior and the insulation standard of the building without loss of comfort.
With increasingly well-insulated building envelopes, however, these savings become smaller, so that the difference hardly remains effective. Where the limit lies can be calculated in advance.
With heat pumps as heat generators, underfloor heating is a prerequisite for effective operation. Warm feet in the bathroom are no longer reasonably possible. Additional heating surfaces are often required.
Basically: before signing a contract, sufficient checking and calculation are mandatory. This includes in particular the heating load (DIN 12831) as well as the annual energy demand for heating and hot water! Based on that, the overall concept is developed. The results from the energy saving ordinance verification are generally not suitable for this!!!
Objective and independent advice can only be obtained from a qualified specialist who does not sell, install, or broker!
Best regards
