Digital shower query

[Prezza]

I'm refurbing my bathroom and would like to install a digital shower, but I'm not sure if my plumbing is suitable as it currently stands. It's a gravity fed, vented system with the expected high cold water pressure and low hot water pressure. I watched a professional plumber install a Mira digital shower on Youtube, during which he stated that you can't have high pressure cold water running into the mixer/controller unit. Is that really the case? I thought the point of digital showers was that they can take the grief out of having mixed pressures? Any help much appreciated.
Cheers

 

[Baths'N'Gas]

Gravity hot feed & gravity cold feed to the pump/processor

 

[Prezza]

Does that mean similar pressures are required?

 

[Madrab]

You can only have one or the other with digital processors.

A pumped processor needs to be gravity fed at both inlets, it cannot accept mains pressure.
The other type is just the processor and only suitable for mains/unvented/combi fed as it doesn't have a pump. If you send mains pressure cold to a pumped unit you will damage it.

 

[Prezza]

Cheers. I have a sneaky suspicion my cold water to the shower may be coming direct from the mains rather than the cold water storage tank. I'll check that tomorrow. If I decide to stick with a mixer are there specific types that can cope with high cold water pressure and low hot water pressure?

 

[Madrab]

If you're refurbing the bathroom then is there no scope to run a new cold feed from the CWSC?

It's just your luck with normal mixers, some can be ok others have problems, with unbalanced supplies.

If you look for one designed for low pressure - <0.5bar. They'll offer the best chance to work ok.