zx5000

Hi all,

I have a slight problem with my shower which is fluctuating in temperature - sometimes going from very cold to boiling hot. I have a centrifugal shower pump located in the loft. The hot water supply is from the hot water cylinder located adjacent to it. The cold water supply is fed from both the the mains supply and the hot water cylinder header tank (there is a tee connection from the tank and the mains).

I have a number of theories why this is happening:-

1. As the cold water is fed from both the mains and the header tank (there is a tee between the header tank and the mains), could the cold water be "competing with itself" and therefore disrupting the supply?
2. The mixer valve is a MIRA unit which has been refurbished (previously to this the water was dribbling out of the shower head) could this be defective?
3. The pump fitted is a basic unit purchased from Screwfix which may not be suitable?

I would be gratefull if anyone can supply me with possible solutions to this problem.

Thanks in advance

Michael