Cold water pressure drop. Don't know why.

[richie4236]

We've lived in our house for three and a half years. In that time the water pressure's been just about adequate in our bathroom and ensuite. We have a hot water tank in the airing cupboard on the landing (close to both showers) and cold water is fed from a large plastic tank in the loft.

In the last couple of weeks, we've noticed that cold pressure seems to be dropping in the ensuite shower, and maybe a little bit in the family bathroom.

The thing is, we haven't changed anything anywhere in the system. The tap pressure seems to be okay, but obviously, they're more than a meter lower, so I guess gravity's doing more work for us with those. Mains pressure is fine, and if I turn the mixer to get more hot water the pressure goes up (good), but I get scalded (bad). So nothing wrong with the hot that I can see. We've got Homecare and BG been in and checked the hot water system for us, and couldn't see anything wrong.

I've tried changing the shower heads and pipes in case, but I don't really know what else to do. Is there any reason the cold water pressure in the house would drop for no apparent reason? I don't really know what to check, so would appreciate some advice from experts. Thanks

 

[Madrab]

There's only 2 things that can do that. A restriction in the cistern or pipework somewhere or the outlet or it's fittings becoming worn and slowing the flow.

You've swapped the hoses/heads so that's removed them from the equation so time to look at the supply or the outlet itself. Is the cold cistern clean and free from any debris?

 

[richie4236]

So I did a bit of exploring and mapped out the pipework. It's left me really confused by central heating.... but the problem with the cold water to the shower is solved.

The cold water supply for the shower is fed directly from the tank; comes down the wall in the airing cupboard and through to the shower mixer tap. In total there's about 3m of pipework. There's an isolator in the airing cupboard and although it looked like it was open when I spun it a couple of times there was a sudden increase in pressure. Wasn't there to see it come out of the pipe, but can only assume there was some debris in the isolator valve which I dislodged. There's quite a lot of silt in the tank, and calcium buildup. I'll deal with that another day.

All good now. Thanks for your help!