@foraloysius - UK & Irish Drains are very different!
In most buildings, other than multistorey apartments or larger commercial buildings in these islands the drains (except toilets) run to outdoor gulley traps. They either just point directly into the gully and flow in through the grille, or they enter just below the surface.
In most setups, we don't tend to connect drains from sinks, baths, showers, washing machines and dishwashers etc directly to a sewer line. The gully trap provides a physical and complete separation.
For that reason, you would typically also run a gas boiler drain to an outdoor gulley. There's no real way of connecting them to a floor drain as they don't generally exist.
It's fine in the mild conditions of the south of both islands but because of the small diameter and low, constant, flow rates they can freeze in a way normal drains here wouldn't and you can get temps low enough to do it.
It's an extremely bad design in my opinion. They really should be connected to a normal sized drain pipe not at risk of freezing.
I can't see any possibility of condensing boilers being connected to to an freezable drain in the USA as the temperatures are much more extreme. I would guess that regulations there, used to dealing with freezing conditions, wouldn't allow it.
