Bear with me because I'm not very experienced! I know the basics but not the jargon!
My girlfriend moved into a house a while back which had been owned by a complete idiot who seemed to think he was a DIY god. He wasn't...
She had an electric shower in her bathroom with hot and cold feeds from the loft above. We couldn't get any decent pressure out of it and it made a dreadful noise, and would constantly stutter as if being starved of water. I took the thing apart and found carbon deposits on the inside and what seemed to be a knackered motor. It was ancient anyway and looked very dodgy so I shut off the electric supply, removed the motor and thought we'd just use it as a non-power shower, afterall the water pressure is fairly decent anyway.
It now works fine for a few minutes, but after that the hot water supply just seems to disappear and you get a noise as if the system is being starved again. I looked up in the loft and found the cold water feed came straight from the rising main (fine as far as i know, correct me if I'm wrong) but the hot water came from the cylinder vent pipe (not good?), just below the outlet.
If I am correct, this means that as long as the cylinder is full and hot, the hot water will flow up the vent pipe and back down into the bathroom, but as soon as it empties slightly, it will stop and so will the shower.
Please could someone tell me if my thinking is correct and why on earth someone would fit a system like this and expect it to work. It's very obviously an addition to the original hot water system, all of which is fine (rest of the water supply to the bathroom comes from pipes under the floor and the pressure is fine).
If anyone has got any advice for me I'd very much appreciate it. I'm getting sick of having to have baths when I stay with my missus!