2.3.8. Data correction, HZ division, drawing pipe feeds<br>

### 2.3.8. Data correction, HZ division, drawing pipe feeds

Data correction

If incorrect results, in terms of heat output or hydraulics, are obtained, then some handling of the data may be done in order to improve the results.

The thermal resistance of the floor covering is significant for the heat output results. The area occupied by pipe feeds is also important – when only 50% of the output from pipe feeds is taken into account, the large area of the pipe feeds makes room heating difficult. It may be advantageous to specify pipe spacing narrower than the one determined. Room heating may also be enhanced by the introduction of peripheral zones.

On the other hand, if one of the rooms has a much higher heat demand (per square metre) than the others, then you may eventually relinquish the covering of the entire heat loss by floor heating and place a convector there. Such a solution facilitates determining supply temperatures and calculations of other HZ’s belonging to the same control circuit.

If the heat results are satisfactory, the changes will be aimed at balancing the system in terms of hydraulics. The error list includes messages generated during calculations, particularly recommendations on the division of heating zones.

Pressure losses may be reduced by, apart from the division of a HZ, changing other data. Increasing insulation thickness reduces downward losses to the floor, which is balanced by higher flow rate. Lower downward losses to the floor implicate lower flow rate, which in turn induces much higher drop in pressure loss (pressure drop is proportional to flow rate squared).

For very small HZ’s (toilets, corridors, etc.) it may be advisable to use pipe feeds for heating, as the introduction of such a small circuit may complicate (or even render impossible) the balancing of the manifold – pressure drop in such a small circuit may be several times lower than that in other circuits.

Despite applying the methods described above, it is often not possible to avoid the division of HZ’s in order to reduce flow rates and pressure drops, particularly in large rooms. If other data changes that have an effect on pressure drops have been made, it is advisable to carry out calculations once more before dividing the HZ, so that error messages with updated recommendations on HZ division can be viewed.

HZ division

To divide a HZ use the HZ pop-up menu displayed upon clicking the right mouse button or use the command “Divide heat. zone” in the “Components” menu (“Functions” → , ). There are two ways of dividing a HZ: without a joint – represented by a green division line, and with a joint – marked with a brown division line (from wall to wall). The choice of division method has no impact on calculations. Proper joints of the floor plate is of structural significance.

All zone data are copied from the original zone. The names of these zones are formed by appending subsequent letters (a, b, c, etc.) to the name of the original zone. If you divide a zone, part of which forms a peripheral zone (PZ), you must amend the PZ data for all new zones.

After making all necessary divisions you must lay pipe feeds to the new HZ’s or enable creation of virtual pipe feeds. To do this you must increase the number of ports in the manifold or enter additional manifolds. To avoid crossing of pipe feeds, new ports often have to be located between existing ports. To place such a port in the manifold, position the mouse pointer on the manifold, press the right mouse button and select “Insert connection point ...” command from the pop-up menu, and then indicate the place where you want to insert the port.

! Increasing the number of connection lines running across a heating zone may cause that the need to divide it advised by the program becomes invalid..

Example: If it was indicated that zone A must be divided into two and zone B must be divided into four, whereas pipe feeds to zones B1, B2, B3 and B4 will run across A, then the division of A may not be necessary. In this case divide zone B into four new zones, do calculations and check whether zone A still has to be divided. Large number of pipe feeds running across a heating zone may change its heat output substantially.

Connecting heating zones to manifolds

By default the “Create virtual connections” option is enabled, as there is no need to enter pie feeds at the initial stage of design.

Virtual pipe feeds are accounted for in flow calculations, whereas their heat output is not taken into consideration. Therefore, pipe feeds between manifolds and the individual circuits must be inserted in the drawing during final design in order to enable both flow and proper heat calculations (after drawing the pipe feeds you can check their connections: disable virtual connections and run connections check). No messages should appear if pipe feeds are arranged correctly.

Each heating zone, apart from those heated by pipe feeds, must be connected to a manifold. To connect a HZ to a manifold it is best to use a “Pipe feed pair” component. In special cases you can use a separate “Pipe feed” for supply connection and another one for the return connection.

! Heating zones cannot be connected to manifolds by means of pipe-runs.

The operating modes (AUTO and ORTO) are important when drawing feed pipes. A short description of these modes is given where the creation of the building construction is described. In the AUTO mode it is best to connect first the nearest HZ to the manifold and then to connect in turn those HZ’s that are further off. This way you’ll avoid laying pipe feeds across HZ’s that have not been connected yet, and which the program in the AUTO mode proposes to connect. It is important how you position the pipes because the lengths of pipe feeds running across individual HZ’s are read from the diagram automatically. If the length on the drawing differs much from the expected real length, you can specify its value (overwrite the default value) for separate segments running across successive HZ’s.

In case of pipe feeds that have a number of bends, in the AUTO mode the program may modify fragments of those feeds in an undesired way (creating, for instance, crossing points). In this case you can press the Shift key to disable the AUTO mode for the time of carrying out one operation and make the connection without using the AUTO mode.

Pipe feed data

The length of the entire pipe feed (used in the calculation of HZ linked to the pipe feed) and the lengths of pipe feed segments running across individual HZ’s (used in the calculation of area and output of passing pipe feed) are taken automatically from the drawing. These values can also be specified by the user, when the default values are incorrect. Note that those segments of pipe feeds that are not within the area of a HZ will not be assigned to it. In particular, if a pipe feed runs along a wall in an area not covered by HZ, it will not be accounted for correctly.

After marking a pipe feed, its data are displayed in the table, including overall length of the pipe feed taken from the drawing and, upon displaying a table available in the “Across HZ...” field, a list of segments of the pipe feed running across separate HZ’s. The appearance of the line used for drawing the pipe feed can be defined in the “Line style” field.

! The lengths of pipe feed segments running across individual HZ’s are displayed only after the connections are checked or after the first calculations are made.

The data below are available in the HZ data in the “Pipe feeds...” field (in this case a list of pipe feeds connected to other HZ’s and running across the given HZ is displayed) and in the room data (all pipe feed segments running across that room are displayed).

- Length – length of pipe feed segment running across given HZ automatically taken from the drawing

- Insulation – possibility of laying segment of a connection line in a conduit (casing) or in insulation lagging

- Pipe spacing – (auto) means that pipe feed spacing taken for calculations will be equal to that determined for the HZ across which the pipe feed runs, if the pipe feed is not insulated. This can be defined as simulation of heating zone by pipe feeds. For insulated pipe feeds (auto) means minimum pipe spacing. Note that, for instance, one segment of a pipe feed that runs across heating zone “A”, may be insulated and spaced at a distance of 10 cm, while the next segment that runs across HZ “B”, may be non-insulated and arranged with a spacing specified for HZ “B”, say 30 cm.

- Utilisation percentage – the default value is 90% of the output of pipe feeds. In some cases 100% utilisation of pipe feed output may be specified, whereas for rooms that are used sporadically a 0% value may be justifiable.