Underfloor heating not warming up – causes and solutions

The most common causes are closed actuator valves at the heating manifold, air trapped in the system, or a faulty room thermostat. First, check the manifold cabinet: all valves (small actuator motors or manual sliders) must be open for the relevant room. Feel the individual flow circuits at the manifold – cold pipes indicate closed or jammed valves. Bleed the affected heating circuit via the bleed screw on the manifold, holding a container underneath, until water flows out without air bubbles. If the room thermostat shows the correct temperature but nothing is heating up, replace the battery or check the programming. If the screed is over 50 years old or the system has not been serviced for a long time, it is advisable to call a heating engineer.