Cold shower water

[Simonj1]

Hi

I’m after some help please. The hot water in my shower keeps going hot and cold and does not stay hot. It’s a mixer shower with one knob to control the temperature.I changed the thermostatic cartridge and it’s a little better but still the same problem. When it’s on hot it goes cold but on cold it says cold so maybe it’s not thermostatic cartridge? All the other taps in the house are ok, so could it be a problem with the hot water indeed or the actual boiler??

or maybe the value I got it also faulty!

I appreciate your help!

 

[JohnD]

you've got a combi boiler, haven't you?

run the shower into a bucket; time it to full; calculate litres per minute.

if the shower head is clogged with limescale, take it off, see if the water gushing from the hose stays hot, and calculate the flow from it again.

 

[rbranco]

you've got a combi boiler, haven't you?

run the shower into a bucket; time it to full; calculate litres per minute.

if the shower head is clogged with limescale, take it off, see if the water gushing from the hose stays hot, and calculate the flow from it again.

would you not check the hot and cold taps independently to check they have equal flow rate, not via the shower itself as if the fault is flow you would not know exactly if its flipping

 

[JohnD]

you can if you want to.

but if flow through the shower is insufficient (through limescale or some other reason) then the boiler will cut out or down when trying to run a shower.

Knowing the flow rate of the shower (by timing the bucketful) is important in seeing if that is the case.

"All the other taps in the house are ok"

if it isn't a combi, then typical cause will be different.

 

[Madrab]

Turn on the shower and re-create the hot/cold symptoms and go to the boiler, is the boiler cycling on and off?