If a heating loop does not get warm, it could be a bad bleeded facility, where air bubbles with time gather in one place in the underfloor heating loop and breaks the water circulation. One such place can be in the floor where the pipe goes in a little bow up and down.

Because air is lighter than water, the air will accumulate in the upper part of the pipe. In that case the pipe must be pressed free of air with a water hose connected to the tap water. It is the same method used when a new underfloor heating system fills with water.

1. Turn off both the supply and return vents.

2. Connect the water......