Hi I went to look at a ariston wrc-nsf direct hot water system today a favour job for a friend. The hot water pressure has been dropping and now after the initial surge there is nothing. This happens on all hot taps. All valves are open. I checked the expansion vessel which had dropped 2 bar from its precharged setting. So I pumped it back up to its 3.5 bar setting. However it's still not working. I have looked in the manual and it says check the line filter however this has been fitted so the strainer part is touching the wall so the only way to get it out appears to be to cut it out. However as it was a job after work I didn't fancy going that in depth and said I'll go back at the weekend. However the flat is only about 5 years old its on a new build complex all new water mains so could this get blocked? Or is there something else I'm missing? Cheers