Unsatisfactory main house water pressure

[itsthejb]

Hi everyone,

As a new home owner, this is my first post, possibly of many. Hi, everyone!

We moved into our 10-year old first home at the end of August. The only real problem we've had is unsatisfactory and inconsistent water pressure, most notably in the 2F showers, but not only (details to follow). Since I'm now passed round three of trying to fix this, I'm calling out for any helpful input in the hopes that round four will finally find a solution!

Details:

- 10 year old David Wilson house in West Berkshire with only one previous elderly owner
- 3 storey, 4 bedroom, 2 bath (showers)
- Combi boiler downstairs and unvented tank on the 2F
- Thames Water have confirmed that the supply pressure is good
- One average plumber and one central heating specialist have yet to solve the problem
- Water pressure is unsatisfactory and inconsistent mostly throughout the house, but with the exception of the utility room
- We have a water softener, but this is NOT the source of the problem since bypassing it makes no difference
- The house was vacant for six months this year before we moved in
- Previous owner said she'd "never had any issues with water pressure". However once we moved in there were obvious issues with the showers
- It's apparently a mega-hard water area. Water softeners are all the rage here and I've heard of the neighbours having to flush their entire plumbing due to limescale build up!

Here's my lovingly-detailed diagram of the utility room under-sink where the action is:

- Pink: supply comes in stopcock (yes, fully open!). This then goes directly to the garden tap. This is fairly powerful at about 12L/min. This then feeds through the water softener value, which is bypassed in this image (and makes no significant difference to the problem)
- Green: after the softener valve, this goes to the utility room sink above. I measured the main tap cold here at also about 12L/min and this is the only cold tap in the house with solid pressure.
- The sink also has a smaller drinking water tap which I measure at about 5L/min, but I think that's just due to the tiny flexible pipe which feeds. For filling up a glass, the pressure here is also good, so I don't think this is a relevant point
- Blue: after this leads into the main house supply (as far as I understand). It's after this that the problems start
- Red: pretty sure this is the hot water feed from the tank upstairs. Also poor pressure, but this is far from the source of the problem

Other pressure measurements:

- There's a downstairs toilet on the same level that delivers a pitiful 3L/min
- The kitchen which is more or less directly above gets about 7L/min. Strange that this is more than the toilet downstairs!
- The problem is most pronounced for the showers on the 2nd floor. You can't, for example, use any taps while someone is showering

The last engineer to come in did the best job of "debugging" the problem:

- From his opinion, the set up is modern and ought to be delivering good pressure upstairs
- It's pretty clear that the problem starts after the blue section. This explains why the utility room and outside taps are decent and everything else is not
- Cold water supply appears the source of the problem (from within the house)
- It's possible to get momentarily solid pressure in the upstairs showers if they've been unused for a few hours. You can get about 5 seconds of decent pressure before it decays to mediocre pressure. Sometimes it's just a dribble.

Most likely I can't avoid paying someone to come out again and it's possible they'll have to do some even more serious work investigating it further before it might get fixed. Posting here in the hope of picking brains before I bite the bullet and have yet another attempt at fixing this

Hope someone can provide insights! Thanks in advance!

 

[Hugh Jaleak]

Unlikely you'll have a Combi Boiler and an Unvented Hot Water Cylinder, Combi's heat the Hot water on demand, negating the need for Stored Hot Water. Possibly a System Boiler, where all the Gubbins are in the one box.

As to your water woes. Can you trace the pipework after the point where the pressure/flow is acceptable? Wondering if they've squashed a pipe somewhere during build, and the previous Occupier has just accepted it. Or has any work been done that could have resulted in some debris getting into the system and blocking it somewhere?

Might be worth, as the problem seems to be after the Blue 'House In' section, isolating the feed to that, attaching a hose to the open end that was feeding beyond that point and reverse the flow using a known 'good' supply. i.e. the Garden Tap, attached to an upstairs Tap to see if anything comes back out?

 

[Johntheo5]

What are these two items??, one is labelled.

 

[CountryFan]

Was the unvented cylinder looked at and has it been serviced? I can see x2 small bore isolation valves which could be part of the problem.

 

[danfre]

Could have a combi and unvented cylinder, cylinder doing bathroom's and combi doing kitchen/ utility.

Has the filter on the unvented been cleaned, same applies if you have a double check valve

 

[Exedon]

What are these two items??, one is labelled.

View attachment 425584

Water softener bypass.

 

[itsthejb]

Unlikely you'll have a Combi Boiler and an Unvented Hot Water Cylinder, Combi's heat the Hot water on demand, negating the need for Stored Hot Water. Possibly a System Boiler, where all the Gubbins are in the one box.

It's a Range Tribune HE cylinder and a Logic Heat 15 boiler. In any case, the problem seems to be before the hot water system.

Can you trace the pipework after the point where the pressure/flow is acceptable? Wondering if they've squashed a pipe somewhere during build, and the previous Occupier has just accepted it. Or has any work been done that could have resulted in some debris getting into the system and blocking it somewhere?

That's the core of the problem at this stage and the motivation for the post: it doesn't seem possible to get more information about the pipe work after "blue" without serious work like removing the entire sink unit and work surface in this room. Granted, we were going to decorate eventually so that might present an opportunity... As for work in the house, no - as far as I can see it's just been painted since new in 2014 and nothing structural. I was indeed wondering what would even be capable of affecting the pressure like this. Yes, crushed pipe seems a possibility but I can't see how that would've happened. Also, yes, I have trouble believing that the previous owner didn't notice the problem, but then it's not out of the question they just got used to it somehow...

Might be worth, as the problem seems to be after the Blue 'House In' section, isolating the feed to that, attaching a hose to the open end that was feeding beyond that point and reverse the flow using a known 'good' supply. i.e. the Garden Tap, attached to an upstairs Tap to see if anything comes back out?

Yes, something like this is interesting. I assume you mean trying to flush it backwards, right? With a view to releasing a blockage. I assume something like that might be a professional next step and less expensive and invasive than starting to rip things out...

Thanks for your input!

 

[itsthejb]

Has the filter on the unvented been cleaned, same applies if you have a double check valve

Cleaning filters has been suggested, yes, but this doesn't explain why cold water in the guest toilet on the ground floor has also lost pressure, considering it's also supposedly "after blue" on the diagram. Therefore even if cleaning filters would help, it seems like not the fundamental problem

 

[itsthejb]

Was the unvented cylinder looked at and has it been serviced?

The engineer who came in last serviced the boiler and was potentially going to do the cylinder as an additional job. However in his opinion there was nothing to do. In any case, there's clearly a problem with cold water supply, so at the least this needs to be solved first.

I can see x2 small bore isolation valves which could be part of the problem.

Do you mean these guys:

I did have a play with those earlier. If I remember, the one on the right could be used to turn off the utility sink drinking water tap and the other one I think can turn off the hot water to the main utility tap. So doesn't seem very relevant to the fundamental problem

 

[CountryFan]

The engineer who came in last serviced the boiler and was potentially going to do the cylinder as an additional job. However in his opinion there was nothing to do. In any case, there's clearly a problem with cold water supply, so at the least this needs to be solved first.

I was thinking more along the lines of if the cold is after the branch into the cylinder.

Do you mean these guys:
View attachment 425591
I did have a play with those earlier. If I remember, the one on the right could be used to turn off the utility sink drinking water tap and the other one I think can turn off the hot water to the main utility tap. So doesn't seem very relevant to the fundamental problem

Yes, those valves. I wrote small bore for a reason, not if they could be operated. Could be a blockage at that point, could be the valve isn’t fully open.

 

[Johntheo5]

The pronounced problem with the showers on the second floor.......is the cold water supplied from the balanced cold from the combination valve set to the UV cylinder?, there could be a problem with the PRV or its filter may be dirty?.