Arrangement for heating a medical fluid, medical functional device, medical treatment apparatus and method

An arrangement for heating a dialysis liquid during an extracorporeal blood treatment, comprising:

• at least one electrically operated first heating device comprising at least one first warm section configured to heat during operation of the first heating device, and at least one first cold section configured to cool during operation of the first heating device;
• a first area for receiving the dialysis liquid to be heated, wherein the first area is in heat exchange relation with the first warm section of the first heating device;
• and
• a second area for receiving used dialysate, wherein the second area is in heat exchange relation with the first cold section of the first heating device,
• wherein the first area and the second area are adapted such that heat is drawn from the used dialysate and transferred through the first cold section and through the first warm section to heat the dialysis liquid.