8.4.2. Graph of fitting ts/(s and optimisation of ts/(s on the basis of the graph<br>

### 8.4.2. Graph of fitting ts/qs and optimisation of ts/qs on the basis of the graph

Available supply temperatures are marked as horizontal lines in the graph. The range of scale depends on ts/qs min for the control circuit and ts/qs max of this circuit (defined in control circuit data in project options). Rooms assigned to this circuit (rooms with HZ’s connected to manifolds assigned to this circuit) are marked on the vertical axis.

The dashed vertical green line marked on the horizontal axis with a triangular slider indicates the current supply temperature setting. To change ts/qs you can use the numeric field beside the ‘Determine’ button or drag the slider or the line with the mouse pointer to the left or to the right.

The main feature of the graph are the intervals (ranges) of supply temperature determined by the program fitting the individual rooms. The fitting ts/qs is such temperature, that enables attaining from HZ’s within the room an output equal to heat demand to be covered by floor heating. These intervals are indicated by horizontal lines positioned at the level of the room name:

The green horizontal line in the drawing above indicates that the required floor heating output will be attained in the “Room”, if the supply temperature is within the range of ca. 39.5ºC to 52.5ºC.

The fitting ts/qs line is green, if it is intersected by the vertical dashed line indicating current ts/qs setting. Blue colour indicates that ts/qs is too low, red colour – ts/qs too high. This may be interpreted as expected underheating or overheating of the room. In practice, however, it may occur that the room indicated by a red line (expected overheating) will show shortage of output, because the variants of small spacing in the pipe laying pattern may be rejected due to non-compliance with the standard with regard to floor surface temperature (tfs/qfs).

! The interval of fitting ts/qs displayed on the graph may in practice be discontinuous – the determined ts/qs is within the interval range, but the calculation results indicate shortage of or excess output. Such a situation is particularly probable, when a narrow range of permissible drop of medium temperature in the circuit is specified (e.g. Dt/Dq max. is 10 and Dt/Dq min is 6). However, in such cases the shortage or excess output is usually low.

It may occur, that the required output cannot be provided by floor heating (e.g. when the required output from square metre is too high) and the ts/qs interval is empty – “No fitting ts/qs” message is displayed, accompanied by a red arrow pointing to the left or a blue arrow pointing to the right. The arrow type indicates the reason why there is no fitting ts/qs interval:

– indicates that all available ts/qs cause underheating of room. Most often the cause of that is that the heat demand per square metre of effective area of HZ is too high – due to the limitation of floor surface temperature, the maximum output from square metre of surface is ca. 100 W. Note that max. tfs/qfs is defined for a point, not as an average. Therefore the limit average output may differ significantly from the theoretical value of 100 W.

– indicates an opposite situation - all available ts/qs cause overheating of room (output obtained from HZ is higher than required – does not mean that maximum tfs/qfs is exceeded!). This often happens in case of rooms situated in the interior of a building, where heat losses are very low.

Buttons at the bottom of the graph window:

“Determine”

Optimisation of supply temperature. Similar to the ‘Determine’ button on the control circuit bar – determines optimum supply temperature.

“Adopt”

Adopts temperature currently set on the graph, no matter whether it was determined by means of the “Determine” function or set manually. The graph window is then closed and the value specified on the graph will appear in the “Supply temp.” field of the control circuit bar.

“Cancel”

Cancels the changes made on the graph or in the numerical field and closes the graph window. The supply temperature remains the same as it was before opening the graph.

The graph is an excellent source of information on the expected results of calculations. It helps determine, without studying numerical results, which rooms will be provided with the required heat output and which will not. You can then go back to editing right away and modify data, and then, after analysing the graph again, see whether the changes have produced desired effects.

Virtually all parameters of rooms and HZ’s in rooms accounted for in the calculations have an effect on the range of fitting ts/qs, that is on the length and position on the graph of the line assigned to the room. The most important parameters are:

- required output in W/m2, which follows from the effective area of the HZ’s in the room and the value of Qfh/Ffh,

- type (thermal resistance) of floor covering,

- range of permissible temperature differences (Dt/Dq – temperature drop of heating medium in the heating circuit),

- available pipe spacing values,

- presence and type of peripheral zones,

- area occupied by pipe feeds and the manner of taking account of them.

The changes in these parameters have an effect on the changes of the fitting ts/qs interval, and in consequence on calculation results obtained at given supply temperature.

Other use of the graph is the maximisation or minimisation of ts/qs. The graph shows which rooms are “given up” (we allow their over- or underheating) by, for instance, reducing the supply temperature, or the opposite – how much can ts/qs be decreased without “giving up” any room.

For each temperature within the range between tsmin/qs min and tsmax/qs max the system is optimised and temperature quality graph is plotted. A line indicating temperature quality is displayed in the temperature optimisation preview. To hide or display the quality graph check / uncheck the in the lower part of the window..