Boiling water tap - PRV, filter, TMV order

[a546345]

Thinking of getting one of these. The mains water is very hard where we live.

I want to plumb in a decent filter on the feed to the tank, not the expensive proprietary filter which is available as an addon.

I want to use one of these
https://www.pozzani.co.uk/product_info.php?products_id=158

However that filter would be in a utility room about 5m away from the kitchen sink cupboard and it also feeds a water dispenser on the fridge.

Here is the standard installation diagram for the tap and tank


Here is the diagram for where the proprietary scale filter is installed. It only filters the water going to the tank. The water going to the cold tap, and the cold feed to the TMV is not filtered.


So if I use the proprietary solution, then it looks like this as a block diagram.



I want to do this instead, where everything to the left of the black line is in the Utility room, and the right hand side is under the sink. That means I have 2 pipes going to the sink, which is fine, because I can use the existing 15mm hot and cold feeds.

Is this still safe with the way the PRV would be connected?

Cheers.