New shower/old boiler problems

[kathyb]

We've just had a new thermostatic shower installed, and it runs very well. However, when I run the washing machine the shower starts to drip - quite heavily - almost enough to wash under.
I'm not sure if this is related, but we have an old boiler, and the pressure relief valve needs replacing.
My plumber, who installed the shower, just waffled and said it's because of cold water/hot water pipes running off the boiler ?! He did not seem to think it can be fixed.
I'd be grateful for someone's theory on this!
thanks
k

 

[Jordon]

Sounds like either a faulty shower unit or he didn't fit the non returns in the shower, what's the pressure and flow like in the property?? Doubt the boiler has anything to do with it.