On the tiles we do not notice the areas that are heated (not cold, but also not warm), but we do notice the areas that are unheated (unpleasantly cold), e.g. tiles in the utility room or under the stairs.
Do all rooms have the problem that they don’t get warm or only the living room and bathroom?
Does the heating circuit pump run at some point? If yes, what is the temperature of the supply and return flow when it runs?
Are the valves on the heating circuit distributor fully open?
Is there still pressure on the heating circuit or do you possibly have a leak?
Are domestic hot water times set?
Is there a manual?
What adjustment options are there for the heating curve?
My personal suspicion is that the target room temperature of 35° somehow shifts your heating curve so that the heating does not work properly or, as nordanney wrote, the valves are not fully open.
Source bosy-online.de
What can be adjusted (how is the heating curve defined)?
The heating curve is defined differently depending on the manufacturer and/or controller.
The simplest heating curve is a straight line, which is determined by at least 2 points, e.g., at an outside temperature of +10 °C the supply temperature is 40 °C, at an outside temperature of -10 °C the supply temperature is 60 °C, the remaining values are linear.
However, most heating curves are somehow "curved" to represent, for example, the heat output of radiators or underfloor heating more realistically.
For many heating curves, only 2 values can be set, usually the slope (gradient) and the target room temperature, or the slope and a parallel shift (level), or the slope and the starting point (curve start).
For some manufacturers/controllers, the heating curve is determined by 3 parameters: slope, level, and target room temperature. The slope is the gradient of the curve, the level is a parallel shift of the entire curve vertically up or down, and changing the target room temperature causes a shift of the entire curve along an oblique room temperature line. See the first 3 graphics showing a shift of the heating curve with slope 7.5 (manufacturer-specific) after a 5 °C higher or lower target room temperature.
The slope or steepness of the heating curve defines how much the supply temperature should change depending on the outside temperature (see figure 4). Possible slopes vary greatly depending on the manufacturer, many controllers use slopes in the range of 0.1 to about 3.5. For underfloor heating, the steepness usually is in the range of 0.5 (i.e., flatter curve), while for radiators the curve will be steeper (e.g., 1.3). The worse the house is insulated, the steeper the heating curve generally needs to be.
The level shifts the entire heating curve vertically up or down (see figure 5). This can be used to compensate for inaccurate temperature sensor readings or generally correct the heating curve if it is always about the same amount too warm or too cold at all outside temperatures.