PANEL HANDBOOK aH72 SK
V 6.0
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Important. The heat transfer fluid is essential in areas with minimum temperatures equal to or below
0 degrees to avoid freezing, and must also be able to withstand high temperatures. Its freezing
temperature should be checked with a density meter.
There are areas where recirculation of the heat transfer fluid may be sufficient to avoid freezing.
The filling station supplies pressure and flow rate that allow optimum fluid velocities for the dragging
of air bubbles by purging the circuit. Thus, in addition to filling the system, the circuit is cleaned and
the glycol is pre-mixed with water.
4.8.5
Installation system bleeding
In an installation, air pockets are one of the main problems: they affect the panel connections, reduce
the flow of the working fluid and therefore the performance of the system, and also damage the glycol.
For all these reasons, correct purging is essential. If this operation is carried out using air bleeders, it is
important to place a shut-off valve before the air bleeders to ensure that the circuit is completely
watertight; if air separators are used, they will have a bleeder with which to eliminate the micro-
bubbles as many times as necessary during the start-up process.
There is a risk that the speed of the fluid is capable of drawing the bubbles into the circuit without the
bleeders being able to evacuate them. This is why it is necessary to have an air separator. This must be
installed in the hot pipe and at the lower part of the circuit, which facilitates maintenance.
A larger section reduces the circulation speed, allowing the bubbles to stop being dragged by the fluid
and to rise. The air is expelled with the bleeder.
4.8.6
Pressure and flow adjustments
Pressure and flow are the last parameters to be controlled at start-up.
To regulate the final pressure of the installation, the drain valve will be opened until the appropriate
pressure is reached. It is recommended that the expansion vessel is 0.3 bar below the final pressure of
the installation. In this way, the remaining heat transfer fluid in the vessel can be released into the
circuit in the event of outside temperatures lower than those at the time of filling, and dryness or
sticking to the wall of the vessel can be avoided.
Example of recommended system pressure:
Initial pressure in the installation = 1.3 bar +
0.1 x H (height in meters of the installation)
Pressure in the expansion vessel = Initial pressure of the system without operation
