Single Radiator Cold:The cause may be down to the manual valve on the radiator being off or an incorrectly set thermostatic radiator valve (TRV). There could even be a fault on either valves. There may be a requirement to replace one, the other or both.Incorrectly Set Lock-shield Valve: Open the manual valve fully, then remove the domed plastic cap that covers the valve and using an adjustable spanner open the valve so the radiator can warm. A Battersea Plumber can diagnose and resolve central heating problems.Corrosive Deposits: could be blocking the inlet and outlet pipes. Flush out or replace it if necessary and consider adding corrosion inhibitor to the system.Radiators Cold With Boiler On:This may be a result of a defective pump causing it not to run or pump, correctly, with a possible incorrectly set or defective pump timer or thermostat. Should the settings be correct, then, isolate the power and inspect the electrical wiring and connections. The best idea is to call a professional plumbing service like Battersea Plumbers who can check pumps.Top of Radiator Cold:This is possibly an indication that there may air trapped in the radiator. A bleed may be necessary so you should open the bleed valve on the top corner of the radiator and release the air.Middle and Bottom of Radiator is ColdCorrosion may have formed and caused a blockage or restriction that limits the water flow. Take the radiator off the wall and flush it through, or visually inspect and replace if it is in a bad way. Introduce corrosion inhibitor to the system when complete.Multiple Radiators Cold:First action is a thorough check to make sure that the zone valve thermostat/timer is not set incorrectly or faulty, and can be reset. Once everything is set correctly, turn off the power and visually check the wiring connections in accordance with the manufacturers operating manual. The zone valve itself could be faulty, or the system may need a balance.
