Intermittent hot water

[martlewis]

I have a boiler that has a mind of it's own. Every now and then the hot water will run cold half way through filling sink or bath and then takes ages before boiler comes back to life.

I've had someone out and they replaced the fan as it was seizing but the problem is back. Any suggestions what it may be?

 

[bluesky]

could be the flow switch,

 

[aggis]

Need to know make & model to help...

 

[pobsdad]

APS?NTC?Blocked plate h/ex?

 

[Alpha man]

Bit more info would help??