DIY Doctor UK DIY Forums

I have a problem with my combi boiler shutting down when hot water is called for but only on the thermostatic shower mixer and on the standard mixer kitchen sink tap. The heating works fine, and if I open the bath hot tap and the basin hot tap all is okay except sometimes the water can get too hot. When I turn on the hot tap at the sink the boiler comes on starts to make a kettling noise and then shuts off and after say 5 seconds it will fire up again. It is the same with the shower mixer, hot/cold then hot/cold etc... The boiler is new and I had similar problems with my old combi. Can someone please help me on this ?

Since the boiler is new, then it should come under an extended warranty (of 3 years) if installed and certified by a corgi fitter. Phone up the manufacturer, explain the situation and take it from there.

You say the problem is identical to your old boiler problem. So is the boiler really the problem or could it be something else.
As it's a new boiler its worth checking the operation requirements with regards to minimum water flow pressure - should state in manufarturers specifications. Many of these require a minimum bar of pressure in order to operate.

If you type the key words of your question into our search box to the left of the site you may find the answer is already posted or is in the DIY projects section of the website. Every post goes through a monitoring process and using the search box may speed up your answer.