Mixer shower runs cold after a few mins

[trev159]

Hi

I live in a 1st floor flat that has a worcester bosch junior combi boiler. Over the past few weeks the shower (running from a mixer on the taps) runs hot for the first few minutes but then cold. It will return to hot after a few minutes but obviously this is not ideal. The shower head is slightly scaled but not majorly. I have read that this can cause a problem. The boiler was installed in 2008 April. Can anyone help

 

[muggles]

Is anything else turned on or being used while the shower is in use? On a combi boiler it should really have a thermostatic mixer, is yours thermostatic?

 

[trev159]

No. Nothing else is turned on and we don't have a thermostatic mixer. Just balancing the hot with the cold. When the problem occurs even with the cold tap off, the hot tap produces only cold water until the boiler refires again.

 

[twgas]

Clean the scale out or replace the shower head before anything else. Showers restrict the flow, even when clean, it may be your problem.

 

[trev159]

Thanks for your help. Looks like that did the trick.