Bull. We hit water setting the toilet. Not a really good thing....fortunately it was a short run which was just in the bathroom. Just capped it off and went on. Bathroom is plenty hot anyway because the whole heating system enters through a conduit in the floor and runs along the wall toward the manifolds.
Once you have the heat running, you can easily locate the lines using an IR thermometer. There will be about a 1 degree temperature difference between "over the line" and "between the lines" | 
blank zones in in floor heat
