Air-water heat pump current consumption and data

it is purely for heating water and has 100L.

Honestly? Grab your plumber and 100€ and connect the heat pump directly to the underfloor heating. Everything else is nonsense.

Honestly? Grab your paramedic and 100€ and connect the heat pump directly to the underfloor heating. Everything else is nonsense.

I have already suggested that x times, but he is attached to his buffer + pump ;)

Honestly? Grab your plumber and 100€ and connect the heat pump directly to the underfloor heating. Everything else is nonsense.

I have in mind that with a high and desired heating curve (bathroom runs at 23-24 degrees) including buffer, the consumption is still moderate.

You ask questions where everyone says the design is fine and you’re looking for the flaw because the temperature spread isn’t 5K but 2.5K.

It’s the same discussion as with humidity. You don’t have controlled residential ventilation but want the values as if you had controlled residential ventilation.

Feel free to correct me if I remember it wrong.

no, I just want to understand if I don’t have a flaw in my thinking.

My reference variable is the buffer temperature.
If I have a small temperature difference in the underfloor heating of 2-3K at -10° outdoor temperature, it is of course even smaller at higher outdoor temperatures, which in turn causes the heat pump to short cycle.
Wouldn’t it therefore make sense with my hydraulics to increase the temperature difference in the underfloor heating and work with higher pressure, so that 1) the heat pump has more flow and thus more efficiency, and 2) the buffer tank doesn’t heat up as quickly?
The underfloor heating doesn’t care whether I have a 2K or 8K temperature difference, since the circuit is independent of the heat pump.

By the way, my HTHK has a temperature difference of 6K, while my utility room has a temperature difference of 1.5K and is almost a hydraulic short circuit.

My consumption is pretty constant at 28-30kWh, despite a high heating curve (18/30, 0/35, -15/38)

Wouldn't it make sense in my hydraulics to increase the delta T in the underfloor heating and work with higher pressure,

Actually, it is done exactly the other way around. Small delta T, but high flow rate. How is the heat supposed to be transferred if you keep supplying more and more heat (= high flow rate) to the underfloor heating?

The underfloor heating doesn't care whether I have a 2 or 8K delta T, because the circuit is independent of the heat pump.

The underfloor heating doesn't care. The energy consumption does. If you have an 8K delta T in the underfloor heating, "cold" water arrives at the buffer and has to be reheated with high energy input. If it arrives "warm," it requires only little energy to reheat it appropriately.

I've suggested that x times already, but he clings to his buffer + pump ;)

Then the heating engineer gets a kick in the butt and a "good one" is chosen. It's quite simple.

In your drawing, you can clearly see the reason why a buffer tank in underfloor heating is absolutely nonsense. First, heating the buffer tank nicely and then supplying lower temperatures to the underfloor heating. Any normal person goes directly into the underfloor heating at 33 degrees (with more flow than your 900 liters/min).

I don’t understand that, because if the heat pump is set to a 5K temperature difference, but the underfloor heating only delivers 3K, then the heat pump automatically throttles the flow rate down, right?