sorry i did not sponge out the f & e.
This isn't compulsory, but it removes the risk of debris in the F&E being dragged into the system.
Some people think that it stops bits of rust and magnetite being drawn in, but I'm more concerned with bits of rotting rodent, bird feathers, wasps, wood, roofing felt, plastic shavings from when the cistern was installed, insulation, and some other very odd things that I've found in F&Es over the years.
I just closed off my main stopcock which supplies it. and drained from downstairs for a couple of minutes water into my gulley. it came out ok. and the cistern level was the same when i checked.
should i do it again in the step by step order you listed?
Do what you like, but
the test is not whether it tops back up, but whether it drains away and empties the cistern, with the water off.
also i know sludge builds up over time, and if it is not a blocked cold feed, do you suggest any cleaner i could use ?
How can anyone propose a cleaner, or a cleaning method, when the problem isn't yet diagnosed?
also about your first point there, surely if the system does top back up then it's not a blocked cold feed?
WTF? The water to replenish the cistern comes out of the float valve, not up the expansion pipe.
i know it is to see if the water drains away, but if it does and water didn't top back up that WOULD mean a definite blocked feed??
No, but I now see where you're confused.
It would mean a blocked cold
supply, which is a similar sounding thing, but an entirely different fault with an entirely different solution.
When people talk about a "blocked cold feed" in an open vented heating system, they are referring, exclusively, to the connection from the F&E cistern into the path of the circulating water.