Mixer Shower - Low Pressure?

[Danm1les]

Hoping someone can help. We have a combi boiler and a mixer shower upstairs. Pressure has always been great, almost too much pressure! This morning had a shower and the pressure was probably 30-50% of what it was the day before. Taps and everything else are the same pressure, so assuming its a shower based problem?

Its a fairly standard mixer shower, so hoping it can be repaired instead of replaced.

Any help would be appreciated! Plumber is tricky to get hold of this time of year

[Greenmantle]

So questions for you to answer?

(1) Was it fine "super power" yesterday?
(2) Does the mixer shower have the standard knobs - temperature and open/close?
(3) Do I run my mixer shower on full hot - past the safety switch on the temperature knob?
(4) How old is the mixer shower?
(5) Do I have hard water or do I have a water softener?
(6) Do you have a separate shower pump - Stuart Turner etc.

Most mixer showers have things called cartridges. These are replaceable parts. In addition the hot and cold inlet will have a valves that are replaceable as well.

When you have showers in your house that are 25 years old then you kind of get interested in how they work!

[Danm1les]

Greenmantle said:

So questions for you to answer?

(1) Was it fine "super power" yesterday? Yes
(2) Does the mixer shower have the standard knobs - temperature and open/close? Yes
(3) Do I run my mixer shower on full hot - past the safety switch on the temperature knob? Possibly, will check!
(4) How old is the mixer shower? Less than 7 years.
(5) Do I have hard water or do I have a water softener? Yes to hard water, south east, and no softener.
(6) Do you have a separate shower pump - Stuart Turner etc. No.

[Greenmantle]

Danm1les said:

Greenmantle said:

So questions for you to answer?

(1) Was it fine "super power" yesterday? Yes
(2) Does the mixer shower have the standard knobs - temperature and open/close? Yes
(3) Do I run my mixer shower on full hot - past the safety switch on the temperature knob? Possibly, will check!
(4) How old is the mixer shower? Less than 7 years.
(5) Do I have hard water or do I have a water softener? Yes to hard water, south east, and no softener.
(6) Do you have a separate shower pump - Stuart Turner etc. No.

Before taking the shower apart try and run it on full cold. I don't know if you can turn the boiler off to do this.
I am presuming that the combi supplies just the hot side.

If the cold pressure is fine then maybe its just the valve on the hot side that needs replacing. It could also be the mixer cartridge since that is in series and sits after the cold and hot valves.

Most showers have a cog mechanism so when you turn the open/close it opens or closes "together" the cold and hot valves. All the cogs are plastic while the vales themselves are brass. Overtime the brass seizes up and the plastic cogs are not able to turn one side or both sides (hot and cold).

The cartridge then mixes the hot and cold based on the position of the temperature knob (eg more hot or more cold).
There is usually metal gauze which can get silted up. A number of times I have let a cartridge soak in a glass jar of de-scaler and that has returned it to new.

If you are going to have a go yourself then research the make a model and take pictures so you know how the cogs fit. Remember to put towels between the gap so no water drips behind the tiles. There will be residual water between the valves and shower head so you need to be able to drain that into the shower tray when you open up either the valves or the cartridge. Some sort of flat plastic underneath the shower gubbings will re-direct water into the tray.

[OutInTheShed]

If the mixer is the 'normal' bar style, then you can replace it with a generic one from ebay or wherever, then attempt to fix the old one at your leisure.

It could be as simple as mesh gauze on the inlet which is now full of crud.

[Danm1les]

An easy resolve... came home last night to be greeted by the water company working on the road looking for a leak. Turns out the whole road has a problem. Shower was ok this morning, so assume all sorted.

Thank you for the advice though!

[Dr Mike Oxgreen]

Yep, before I even scrolled to the OP’s follow-up, my answer was going to be: before doing anything else, log in to your water supplier’s web site and see if there are any reported supply issues affecting your area. Low pressure is quite likely to be their fault and nothing to do with your plumbing.


OP… do you live in the Southampton area, by any chance?

https://www.bbc.co.uk/news/live/c627wyvxp65t

Edited by Dr Mike Oxgreen on Thursday 19th December 10:04