low water pressure on cold - but good on hot!?

[darrenptalbot]

Hi

I have a problem with poor cold water pressure, but good hot.

I have a combi boiler.

The water authority have just replaced my outside valve, and its recording 40m head, with 10 litres flow.

I have good hot water pressure through the combi, but then poor cold - so bad that an electric shower installed by previous owners is virtually unusable.

I have checked both the inlet valve (is fine, confirmed by fact that hot water pressure & flow is good) and the intermediate valves (all appear to be open).

If it was hot water, I'd put it down to scaling up, but not sure this would have the same effect on the cold water!?

Any ideas gratefully received!

 

[BingoBongo]

is the cold poor at the tap or just the shower.shower may have a filter that is now choked

 

[darrenptalbot]

at downstairs tap and shower.

I've removed the shower filter (I'm about to bin the shower, so happy to risk it being being killed!) so have taken that out of the equation!

I was brainstorming what could cause restricted flow - could too many 90 deg bends in the system restrict it? Not sure this is the issue, but it's one to check!

 

[BingoBongo]

where does the supply to the hot tee off from?

 

[darrenptalbot]

Not sure - I'll have to clear away some floorboards and boxing!

 

[picasso]

10 litres per minute @ 4 bar I reckon your cold supply pipe is damaged somewhere or is seriously under sized.

 

[darrenptalbot]

There's no obvious pipe damage. Initially I thought it might be scaled up pipes, but quicly discounted that after realising that the hot had a good pressure and the cold has at some taps.
I guess I'll have to track the pipes and the joints/ valves to narrow it down...

 

[darrenptalbot]

Any ideas from anyone?