UFH filling

[bassmonster]

Hi all,
Just reading through manual for underfloor heating which says that UFH must never be filled via filling loop from boiler. Left me a bit puzzled... Why is this?
It's a single circuit system.

 

[oz-plumber]

Sounds like a 'typo' error, or a translation inconsistency.

Can't see a reason why it couldn't be filled via a boiler.
In fact - bar testing - always have done this