How long do indirect hot water cylinders last

[Gasguru]

The hit take off from the cylinder should rise as it runs across to the vertical vent and feed pipe...is this the case? Otherwise air can collect in the cylinder.

 

[ross94]

The hit take off from the cylinder should rise as it runs across to the vertical vent and feed pipe...is this the case? Otherwise air can collect in the cylinder.

Hi, the short pipe run from the top of the cylinder is raised about 100mm to an elbow joint then from there it runs in a straight line to the tee vertical joint.

 

[fixitflav]

Hi, not sure what you mean? The cold supply comes down from the attic via the airing cupboard where the cylinder is located, from there the hot and cold pipes go under the floor to the bathroom. The power shower is mira vigour which has a small pump built into it.

I believe I'm right in saying the shower should have a dedicated cold supply from the CWST, don't know whether it's mandatory, somebody might confirm.
But I doubt that's the cause of the gurgling. Some photos would be useful.