Mains water blockages/partial blockages

[Phil]

I'm about to go to my third partial blockage this year in different houses. The problem with this house is the ensuite electric shower and basin tap have very very poor flow (normal pressure) but the rest of the house is fine...this is mains cold and the system is open vented.

The ensuite has had very little use and sometimes the water is bitty and yellow when they turn the cold tap on.

All these issues are always is 100 year old houses, the other two occasions I tried everything to clear the blockage as well as hunting everywhere for a partially closed valve under a floor, a backwards way stoptap, blocked strainers, check valves etc but none found. I ended up running a linking pipe from where I knew was good pressure to the dodgy part of the system and has always worked.

I've yet to find the section of pipe that can cause this problem.....in others experiences what is causing this? These are all old houses where the systems have been updated so many times and is a mixture of lead/imperial/metric pipe. I.m not getting confused with tank fed here, the pressure is always 3 bar + but next to no flow.

 

[Phil]

Just got back from this job and was lucky enough to find an almost fully closed stoptap under the floor. Had the floor been laminated over or solid wood I would have never have found it and I would have had to run another feed under the floor and tee into a decent pressure pipe.

 

[Terry_the_piper]

Hard water area? Scale can slip down pipe to almost close off elbows.