Haven't noticed much in the winter as mainly been using domestic cycle with solid fuel. Now the weather is warm have noticed not much heat from the solar panels. Temp this morning at the panels was 74c and in the tank 19c. Checked in the loft where the hot water tank is and its luke warm, looked at the pressure and its 10 bar which is normal, green light on saying that pump is on to cycle the water around. No leaks that I can see. System is quite old but always been working and we have it serviced every 2 years as per installer.
Any ideas what I may be missing?