Calling Piglet John? Shower bursting cold water and otherwise low pressure

[CrochetBelle]

We have a shower installed that runs off the combi boiler. Worked great for about a year then noticed the pressure drop dramatically. I have to have the shower temperature down to nearly the coldest setting or its boiling hot. Then every few minutes the pressure picks up for about 20 seconds but it's freezing cold!! This can either happen once or twice, or continuously for the length of the shower.

I notice the pressure gauge on the boiler keeps dropping and needing to be topped up so is it linked to this?

I am with Housing Association and have an annual gas inspection next week so if it's likely to be a boiler issue I can mention it then. If it's a shower issue, I'd need to have my own plumber look at it, as I never got round to asking permission to put it in (though HA are aware, I just don't have the paperwork)

This has been going on 18 months plus now, and I miss my strong hotel-like shower which really helped with chronic pain

@pigletjohn

I'm not PigletJohn but I had this problem too years ago. In our case the pressure kept dropping because the boiler needed a service and the expansion vessel needed 'recharging'. After that it was fine. Not sure if this is the answer in your case though. I'm sure Piglet will be along soon.

If the pressure gauge goes down when cold and up when hot, that's the pressure vessel. If might need pumping up (cheap) or changing (more work).

This will not cause your shower problem. If it has developed over time, it might be restricted flow. Try taking the shower head off it case it is clogged with limescale.

Test the bathtap and the shower flow into buckets and time to fill. Note how many litres per minute they each deliver.

it could be the flow detection sensor in the boiler.