I have a well established oil-fired central heating system (installed about 30 years ago). The Trianco boiler has 2 water systems with 2 Grunfos pumps.
The hot water drawn from the 160 litre cylinder is not very hot although the radiator in the bathroom, on the same system, is hot.
I can feel the top pipe of the indirect coil on the cylinder is hot to touch, however the lower pipe is cold.
I have opened the bleed valve and removed the air, but the problem persists.
The immersion heater does heat the water up as a back-up but that's an additional expense.
I have checked that the pump is operating okay.
Does anyone have any suggestions or a series of checks to carry out.