shower goes cold.

glenbois

I have a thermostatic shower.
I have a worcester bosch combi boiler.

Things that have changed recently;

Mains water pressure has increased from very good to very very strong (I don't think this is the problem as the increase was about 9 months ago)

The shower head has been replaced from a big head to a smaller head.

The boiler's pressure was down to about 0.5, so I have knocked this up to about 1.8 (haven't checked if this has made a difference to the problem).

Boiler and shower are about 45 months old.

We dont suffer from limescale.

3 times now the shower went from normal temp to very cold and i could hear the boiler cycling on and off.

Is this due to the boiler's pressure being way too low at 0.5 or could it be the water pressure coupled with a smaller shower head be the problem?

Would the solution be just getting a bigger shower head or does something else need to be resolved?

Thanks in advance.

keystone

You certainly have a boiler problem if the pressure keeps dropping.

Although the hot water circuit is effectively "straight through" if there is insufficient pressure on the pressurised side (the heating circuit) then the boiler won't work properly to produce hot water.

Your first step is to sort out why the boiler pressure keeps dropping. When was it last serviced?

Once you have done that then that is the time to investigate the shower if the problem is still occuring.

What is the model number of the boiler and the make/model of the shower?

Cheers

glenbois

Forgot to mention, boiler works fine for hot water in the kitchen, bath and bathroom sink. Just the shower.

Last serviced in January, all upto date on all services since installed.

The shower is a triton bar mixer shower and the boiler is a worcester Greenstar 24i Junior.

Just used the shower after putting the pressure up on the boiler and all went well.

Not sure how often I should be checking the pressure on the boiler, haven't increased the pressure for 6+ months. Haven't used the central heating since April.

diywhynot

If dhw is ok elsewhere then the mixer is the culprit...could be DIYable depends on your skill set. If you have topped up the pressure to 1.8bar cold then it is too high. Call your RGI to investigate and repair the boiler/CH system.

macman

Is it venting water from the PRV overflow pipe?

glenbois

macman wrote: »

Is it venting water from the PRV overflow pipe?

Is that the one that freezes outside and that stops the boiler until it is thawed out? If so i will check next time i hang out the window.

diywhynot

glenbois wrote: »

Is that the one that freezes outside and that stops the boiler until it is thawed out? If so i will check next time i hang out the window.

No...that is the condensate waste which should be plastic. Pressure relief pipe should be in copper.

glenbois

macman wrote: »

Is it venting water from the PRV overflow pipe?

No everything is dry.

keystone

To make sure that isn't the source (well the PRV passing will be the real source) of the pressure drop tape a small plastic bag over the end of the pipe and see if it collects any water.

Cheers