Switching the buffer storage of temperature sensors

Hello everyone,

my heat pump (BLW Neo) is controlled only via a buffer storage sensor, which is installed at the bottom. When the return flow target is reached, it switches off. After a short time, the return temperature naturally drops again and the heat pump receives a new start signal (- hysteresis).

If you had 2 temperature sensors, one at the bottom and one at the top of the buffer, this would be advantageous for the control. Unfortunately, the BLW does not have this option…. cycling is pre-programmed.

Does anyone know of a setup where you can automatically switch between 2 temperature sensors (bottom/top)? For example, when the heat pump is running, the lower sensor is used; when the heat pump is off, the upper sensor is used.

Or do you have to tinker something yourself?

Buffer tank connected in series or parallel? If parallel, I would convert it to series.

Is installed as separation buffer storage according to Brötje.

Maybe it makes more sense to repair the hydraulics instead of switching different temperature sensors with an external control?

Do you mean a series buffer in the return flow when you say serial?? For that, I would have to have the entire hydraulics adjusted. In addition, I have 2 heating circuits (underfloor heating and a small heating circuit for 3 radiators). Is a series buffer even possible there?