hiya
I wonder if the coil is split in the hot water cyl , as that will cause water to raise on the header tank if the main tank is higher than the header tank
or in other instances if a header tank vent pipe is overflowing that will be a cold feed blockage where it enters the system , due to when hot and cold mix it causes a restriction
indeed ref the smaller tank , or known as a F and E tank, ie feed and expansion tank will be for the heating
hope that’s what ur saying and makes sense , lol
Yup I think thats sounds right haha, I just remembered that I seen a few biggish air bubbles an wondered if it was an air lock
but now when you say blockage, when I ran a bath the other night there was what looked like what I can describe as dead flys lol
Just black floaty flakes but nothing after this all clean.
Ta much