BLOCKED CYLINDER HEATING COIL

[OldDIYplumber]

I think the boiler cycles/shuts down more rapidly when the towel rads are off (understandably as less heat loss). Cylinder stat is already up at 85C, There is so much good lagging on the return pipe to the boiler back from the coil out at the bottom of the cylinder and in the boiler room that I can't get a good temp reading, but guess I should bite the bullet and undo some lagging to check? I have a sensor there at the bottom of the cylinder so I can monitor degrees C 24/7 every 15 mins. It went bad when I had to drain the main tank to replace a shower which had no h/c isolation valves, but think it was on its way out for a while before. Old system.

 

[John.g]

I presume that that sensor is above where the coil return is, otherwise not measuring a realistic temperature.

 

[OldDIYplumber]

I presume that that sensor is above where the coil return is, otherwise not measuring a realistic temperature.

It's right against it.

 

[John.g]

Ok fine, its on the coil return.