What should I do if one or more loops fail to warm up when other zones are working correctly?

If one or more loops in an underfloor heating system are not warming up when others in the system are, you should check the following:

• Check that the corresponding manifold valves are open
• Check that there is a demand from the corresponding room thermostat and/or the thermal actuator is open on demand
• There may be an air lock in the loop, which will require purging. Either shut down all other loops by closing the valves at the manifold or turn down all other room thermostats. This will concentrate all pump pressure to the problem loop and may shift the air blockage. If all else fails the loop can be flushed through with high-pressure water following the instructions detailed in Filling, Venting and Pressure Testing section within the manual.

If circulation is apparent but poor, it may be that the regulating control valve on the manifold requires adjustment. It is also worth checking that all pump isolating valves are fully open.