Combination of Daikin Altherma ECH2O with water-bearing fireplace

Good day,

I found two threads via forum search that dealt with the topic of heat pumps and water-bearing fireplaces. Most opinions were against such a system because it apparently does not make sense to combine a high-temperature system with a low-temperature system. We are currently in the house construction phase and had exactly such a system planned so far because we knew from acquaintances with gas heating (!) the combination with a water-bearing fireplace and found the solution quite charming. Now I have researched for a long time and am beginning to doubt. The problem: when buying the house I specifically bought a buffer storage tank with bivalence function to be able to represent the water supply from the fireplace.

Now to my specific question:
Our water storage tank from Daikin (see below) neither stores heating water nor drinking water but merely functions as an energy storage. Heating water and drinking water are heated via heat exchangers on the buffer storage tank. Could in such a system the combination with a water-bearing fireplace possibly still be sensibly used, since the two types of utility water are not heated directly by the fireplace but only the energy storage?
For me, the motivating aspect was also to distribute the heat from the wood stove as well as possible throughout the entire house and thus not overheat the living room too much while still having the cozy fire effect in a KfW 55 house...

Components:
- Outdoor unit DAIKIN Altherma 3 R 4 kW - ERGA04EV
- Indoor unit DAIKIN Altherma 3 R ECH₂O - 4 kW, 300 liters, 304 H/C Biv (bivalence function)
- Photovoltaic system with 18 kWp without battery storage distributed on two roof sides
- Water-bearing masonry heater (no water jacket, but pipes laid around), with chamotte bricks around by the stove builder
- 194 sqm living space, underfloor heating throughout, KfW 55 house, 36 cm Poroton bricks,

I would be very happy about a few experienced hints! Maybe it is not too late yet to avoid possible mistakes.

Many thanks and best regards
Max

Hello Max,

what is meant by an oven without a water jacket, only with pipes arranged around it?

We have also planned a water-bearing fireplace that feeds the buffer storage.

It must be said that the economic efficiency of this system is difficult to calculate. However, the fact is that the costs to integrate the fireplace into the heating circuit are not insignificant when compared to a "stand alone fireplace." For the patterned (i.e., compatible) technology, materials, and necessary additional work, we were estimated around 12k by the general contractor. In addition, there is the higher base price of the fireplace. Furthermore, when operating these fireplaces, quite a lot of wood is consumed. Typically, they have around 10-12kW total output, which of course requires a corresponding amount of fuel.

By now, I am no longer sure whether it is all that economical. I therefore sell it to myself as a coziness feature.