One radiator does not get hot, rest are all boiling - have tried to bleed it

David_Hopkins_2

Hello,

I am have not long moved into my first house and I am having issue with a downstairs radiator.

All others in the house get nice and hot apart from this one. I have tried to bleed it and when doing so water came out straight away, no air.

Here are some pictures of the radiator. dropbox.com/sh/8rgpu8gir20cejg/AACusWsgV4w5okpbSkCUGYCda?dl=0

Once the boiler and heating has been on for a few minutes, the pipe leading up to the radiator is boiling hot, you are unable to touch it. But the otherside of the valve you turn doesnt get hot. I have tried opening and closing it in both directions but no joy.

Can anyone suggest any issues?

DavidFx

Have you tried opening the other end?
Sometimes the plastic valve caps become rounded and don't operate the valves. Take them off and use an adjustable wrench on the valve spindle.
The one on the left should be fully turned anticlockwise (open) - the one on the right should be turned a half-turn anticlockwise until the radiator gets hot.
If this fails - then either the radiator is blocked or the system has become unbalanced.

Alex1983

Does it have a thermostat radiator valve, if it does it will be stuck shut, you should be able to remove the trv and unstick the pin underneath, I suspect there are plenty of YouTube videos.

David_Hopkins_2

Hi,

I have tried changing both valves to how you say, left fully open, right half a turn. I also took the plastic top off and used a spanner.

What does the system being unbalanced mean? I have hot water too g right up to it I can feel the pipe. It just won't go in.

Also if I leave the heating on for an hour I can feel an ever so slight change in the radiator temp. But it's still cold and patchy.

Alex - no they are little metal pegs that I turn.

Alex1983

Turn all the others off and see if it works then.

greenface

I would suggest thermostats on your rads anyway as you go around maybe decorationg etc . is it the only rad in the room . could you try looping into a good one . maybe its the last , give the whole system a flush etc . troubleshooting central heating is a pain and I'm going through similar atm

DavidFx

All the radiators on a heating circuit are connected between flow (from the boiler) and return (to the boiler).

The water flow around the circuit will tend to take the path of lowest resistance - generally the radiators closest to the boiler. To get flow around the higher resistance paths the flow through the lower resistance paths is restricted.

This is done by adjusting the lockshield valve on each radiator (look it up). Equalising the flow through all the radiators is what is called balancing the system.

A rough and ready way to balance the system is find which radiators get hot first (when the CH is switched on) and gradually restrict the flow through those ( turn the lockshield valve clockwise).

Alex1983 is spot on - turn off some radiators nearest to the boiler (temporarily) and see if that now increases the flow through the cold rad. If that solves it then you need to balance the whole system.