Solar thermal maintenance: preparation of the antifreeze mixture (water and glycol), filling the circuit and cleaning the system.
The ordinarymaintenance of thermal solar panelsit must be performed annually. With themaintenancevarious checks are carried out: rinsing and cleaning of the circuit in which the heat transfer fluid flows, pressure tightness tests are carried out and it is checked that the glycol filling has been carried out properly.
For the correct functioning of thesolar thermal systemit is important to eliminate any impurities and encrustations from the circuit. The solar circuit must be rinsed and cleanedbefore filling the heat transfer fluid.
In the lower part of the circuit there are two taps, one that you will need for filling and the other for draining. Between these two there will be an interception cock which, when closed, will separate the two cocks.
Forclean the circuit of the solar thermal systemyou have to connect the filling tap to the cold water pipe and put it in the open position.
Connect the drain hose to the classic water drain and put it in the open position.
Close the shut-off valve.
Open all the vents in the circuit; open the cold water tap and let it run for a few minutes in order to rinse the circuit.
How to fill the circuit with glycol
In solar thermal system maintenance there is no lack ofcircuit filling. First you will need to prepare the mixturewater - glycol.
Much wonder about the doses ofglycolto use. In reality, the correct percentage of glycol must be dosed on the basis of the manufacturer's instructions. Generally it is taken into account that frost resistance must be ensured for a temperature at least 10 ° C lower than the operating temperature envisaged by the project.
Beforecircuit fillingyou will find yourself facing a starting position that sees the valves:
- filling valve open
- discharge valve open
- shut-off valve closed
- all open vent valves (both manual and automatic)
We find the valves like this because the operation offillingit must be performed after rinsing the circuit.
Place a filling pump between the container and the filling tap. Connect the filling and drain cocks to the container in which you have prepared the mixturewater and glycol.
Fill the circuit until it comes out ofliquidfrom the drain cock. At the beginning, theliquidonly water comes out, observe color and viscosity, as soon as you notice that the antifreeze mixture (water and glycol) starts to come out, close the drain cock.
Do not stop pumping and leave the filling cock open. Wait until the pressure has risen to the desired initial value.
Stop the pumping system and close the filling cock.
Open the shut-off valve between the filling and drain cocks. Activate the circulation pump and let out the air present in the circuit.
Take care to perform a "cold" check. The check must be carried out early in the morning: check that the initial pressure is equal to the value indicated in the project. If you notice that the pressure is lower, add more mixture following the instructions above.
Solar thermal maintenance
THEsolar collectorsthey must be checked often with a simple visual inspection: pay attention to identify deformations on the absorbent plates, partial breaks in the sealant or the presence of obstructions. In case of liquid leaks from the circuit or cracks on the thermal solar panels, you will have to perform an extraordinary maintenance intervention.
For more information on what to check, please refer to the in-depth article:maintenance of the solar thermal system.