Cold Water puzzle to bathroom

[WonkyJ]

Scratching heads a little on this one. Not sure the two issues we’ve experienced are related but posting all info here in case it’s relevant.


Had a en-suite bathroom put in as part of an extension in 2016. Sink, shower and loo.

About 6 months ago the cold tap feed on the sink slowed to a trickle. Shower cold and loo were fine. I replaced the tap a few months agobut the issue persisted. Then about a month ago it sprang back into life.

A few days ago the cold on the shower died. Might get a dribble or nothing from it. It also appeared to run ok for a few seconds if it had been left off for a time and then die down to nothing.

It’s a Hans grohe raindance bar mixer shower in case that makes a difference. Had a plumber in who thought it was prob the filter on the cold in the shower - removed it all , gave it a good clean. Tested the flow without the shower attached (was ok apparently) then reinstalled and resealed it all back in.

Shower ran ok for a day (two 10 mins showers approx) and this morning has the cold had died again after 20 seconds or so. Tap to sink and loo seem fine.

Any thoughts on next steps or where the issue may be, possible solutions ? If it was a bit of debris in the sink branch originally sure would not have gone back against the flow and to the shower? Piping is under tile so reluctant to start pulling flooring up.

 

[picasso]

Unvented cylinder , combi boiler , tanks and pumps ?

 

[tincup]

Might be an air lock

 

[John the plumber]

As Picasso said, what’s the set up regarding your cold water?

 

[WonkyJ]

Unvented mega flow for hot. No tank, mains pressure good.

 

[terryplumb]

Are you certain the cold supplies to en suite are not from a cold water storage tank ?
If you turn off your cold mains stopcock where it enters the property ,does your cold outlets that are troublesome still give cold water ??

 

[WonkyJ]

Are you certain the cold supplies to en suite are not from a cold water storage tank ?
If you turn off your cold mains stopcock where it enters the property ,does your cold outlets that are troublesome still give cold water ??

Yeah positive ... confirm mains stop cock kills all cold in the house after a min or so. Had a chat with plumber today and he thinks next step is to replace the non return valve in the shower unit.

Just got home and the mrs has bought an endoscope and wants to stick it down the pipe !!! ‍

 

[terryplumb]

What did plumber find in shower valves filter ,was it blocked ?

 

[picasso]

I reckon you have a sticking non return valve thats common to the tap and shower .

 

[WonkyJ]

What did plumber find in shower valves filter ,was it blocked ?

Gave it a clean off in vinegar and after a puff or two managed to blow air through it