All downstairs radiators have been replaced and now the one in the hall refuses to work properly.
It has been bled and water is clear so not sure there is any blockage in pipework.
System has been balanced.
All other radiators are working perfectly and all but one have TRV valves.
The hall radiator has normal valves currently wide open and near the room thermostat.
When the boiler dial is turned up to maximum all radiators get hot and this one eventually gets warm after 15 minutes
When heat setting is reduced to 3 this radiator stays cold and its inlet/outlet pipes are cold.
Have tried turning off all other radiators in order to force circulation through the hallway radiator but it stays cold and the boiler overheats up to 100 degrees.
Should the bypass valve prevent this happening?
May be. If your bypass valve have blockage, it does not pass the warm air to different room. You should check up the whole system once.If found any blockage just remove it. After that if there any problem with warm air passing, you have to thought there is problem with circulating pump.Call the technician and solve this problem.
I think your service pipe has problem with blockage. For blockage the warm air can not pass to every room. So it causes extra heat in the heater. By this the heater warms up excessively and the room remains less warmer. You should make a whole check of your service pipe and if found any blockage, remove it. After that, if the problem is not solved call any local technician or your service provider for further help. :arrow:
erm loopslike, I'm not sure what you're trying to tell this guy but you do realise the pipes do not contain 'warm air'?
redeye, does your cold radiator have a Drain off next to it? of so then attach a hose and run it at full bore draining off outside, that may pull the air lock out. you can also find out which pipe is blocked (flow or return) by closing both lockshield and TRV and opening the rad bleed screw, open each valve in turn and if one forces water out fast and the other hardly at all, that narrows it down to which pipe at least has the airlock. It may be a case of lifting the floorboards upstairs again (hopefully you haven't laminated the bedroom floor above) and trying to find a high point (like a hump back bridge in the pipe) in the F&R traced back to the last join or the main 22mm F&R. If you find something like this and you suspect an airlock, it may be difficult to remove it if your pipes run through joists. simply drain system, cut pipe, solder in a 15mm equal Tee and fit a bleed valve, refill and bleed off air. and hopefully now more 'warm air' blockages :wink: