Electric Shower - Pressure Release Valve

[gili51]

I have installed a Gainsborough 8.5kw electric shower today. The water flow was fine until I connected the shower hose and head. As soon as those were connected the pressure relief valve kicked in. I reduced the inflow pressure until this stopped however as soon as I raised the shower hose higher than the shower unit the release valve kicked in again. I have reduced the inflow further and turned up the temperature gauge to reduce the outflow further but it has had little effect. I am limited to 2 drips and a splash before the release valve kicks in rendering the shower useless.
Is there anything else I should be checking before uninstalling and returning to the shop?
Thanks.

 

[namsag]

Have you used your own hose and head as opposed to the one that came in the box as gainsborough are a nuisance for blowing out the prv with anything other than there own heads

 

[gili51]

No, I used their components. I even tried swapping them out after but to no joy. I'm not sure exactly when the PRV started kicking in, but I'm pretty sure it was when I fitted the shower head.