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Low water pressure in one bathroom

I have recently moved my hot water tank from the first floor to the loft and changed to a Telford horizontal unvented cylinder positioned in the eaves.
On changing and moving the water tank to the loft I noticed the water pressure in the ensuite bathroom reduced a little. I have now just upgraded the ensuite by adding a bristan shower / mixer / riser and the water pressure has reduced much further making the shower unusable.
The main bathroom (which hasn't been upgraded) has good pressure and flow especially from the bath taps.
When we measured the pressure at the outside tap it was 3 bar and in the loft it had dropped to 0.9 bar.
Any suggestions or help as to how to fix this or what is causing it would be appreciated? Id love to be able to enjoy a shower and not a dribble. Thank you.

4 Answers from MyBuilder Plumbers

Best Answer

Sounds like a blockage or faulty all water is the same no mater were it goes in the house


Answered 12th Nov 2021

Low water pressure in one bathroom can be down to several reasons, I would recommend trying out the following steps to see if it solves your problem.

Step 1:
Is water pressure bad in all taps or just in specific areas (e.g. shower head, basin tap)?

Check to see if you have a limescale build up on your taps and shower heads.

Step 2:
Check to see if your water isolation valve (switches water on and off) is fully open.

Step 3:
Has this always been an issue or just recently?

Step 4:
Have you noticed any puddles of water when walking in, as this could be a sign there is a leak somewhere.

If none of this resolves your issues. I would recommend having a qualified plumber attend to investigate the matter, as they may have more of an insight once they have seen it in person.


Answered 22nd Nov 2021

Bristan showers usually have a pressure reducing valve installed as standard to reduce water consumption. These are normally behind the gauze filter on the hot and cold intakes. Check the MI to see where they are and remove them


Answered 23rd Nov 2021

A bit mysterious unless your loft is 20 metres higher than your outside tap which I doubt.
Typically I would suggest you should have around 2 bar standing pressure in the loft minimum, unless it is a very high property.
Are you checking the pressure before the UV cylinder controls ? I'm suspecting not. In which case the pressure reducing valve is not set correctly. Other than that, you may have another pressure reducing valve installed somewhere else which might possibly have been fitted to help balance with the low pressure hot, particularly if a shower was involved. Although not really the right way to go about it, the latter can be a work around if a shower has been badly installed or misguided DIY etc.
Either way, even with a poor flow rate, 0.9 bar just doesn't do the maths, even with a blockage as with no outlet open you should still get standing pressure equal to that at ground level, minus the elevation calculation of 1 bar per 10 metres. Just slightly under actually but in round figures that's what it is. Hope that helps.


Answered 2nd Dec 2021

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