Strange Problem with Shower Hot Water

[bassman99]

Hi,

I have a Mira Combiflow shower that was installed about 2 years ago.

It has been working absolutely fine until recently and has now developed a strange problem which goes as follows:

There is no hot water coming through the shower even when set to the highest temperature possible.

The pressure is fine for the shower it is just that no hot water comes out.

The odd thing is, if you turn on the sink hot water tap, hot water comes out fine.

If you then leave the sink hot water tap running slightly, the shower then gets hot and works fine.

As soon as you turn the sink hot water tap off, the shower gets cold!

Both the bath hot tap and sink hot tap work fine.
It is just the shower that cannot get hot.

Any ideas greatly received as I've never heard of this problem before!

Thanks.

 

[Andy165]

Could be a partly blocked filter on the hot water inlet to the mixer valve. Or mixer valve could be scaled up , are you in a hard water area and do you have any protection on your system against scale?

 

[bassman99]

Hi,

not in hard water area - that I know of!

I don't know if the system has protection against scale but will try and find out.

Incidentally, I spoke to Mira and they said it was not a shower problem.
They think it to do with the Supply Feed.
Does this sound feasible?