Solar heating problem

Foleyart

Howdy. I have a solar heating panel in the roof, tubes, one panel, a 300 liter hot water tank and it has been working really well for years. It heats the water very well from April till late October and sometimes later depending on the weather. In the last few weeks it has stopped working. It appears that the lower sensor on the tank is reading a temp of 162 and the collector never gets to that kind of heat. Any ideas on how to replace it ? I suspect the upper sensor may also be faulty. Any help appreciated .

John.G

Doubt if two (or even one) sensors are faulty. What pressure is your system showing??. The pressure gauge should be located near the solar circ pump with two temperature gauges close by.

Foleyart

Hi John, thanks for getting back to me. The gauge is showing 45 psi around 3bar. The tst window on the regulator is showing 162 dg and the collector at its highest yesterday got up to 161.

John.G

3 bar would indicate that there is plenty of fluid in the system except that it is full of air, the collector temp at 161C would also be correct if there is no circulation due to faulty pump or system full of air. Tst should not be that high, possibly faulty , switch off the solar system and pull the probe from its pocket and leave it for a few minutes, then switch on again very briefly if the circ pump starts up as you don't want to thermally shock the coil with very hot liquid, it shouldn't restart anyway if the collector protection temperature is set properly. Once one think it is safe to leave the system switched on, check the probe temperature and it should be reading ambient temp, if this is OK then check that circ pump is running and that there is a flow showing in the flow tube, if fitted.