Radiator - Top part hot, Bottom part cold

[gita patel]

My husband put some air in the pressure tank because water was overflowing in the overflow pipe. I later found that the overflow pipe is shared by the central heating and the main water tank. To establish where the water was coming I channeled two sources separately and left it for couple of days. Found that the main water tank is overflowing at certain times.

Now when I turn the heating on the top part of radiators become hot and the bottom stay cold or just slightly warm.

I can't seem to bleed the radiators as the bleeding bit is on the side of the radiator (the part against the wall) and the key is very small too.

what can I do? Please help me. Temperature is set at 20c

 

[gas4you]

As a general rule rads cold at the bottom indicates a sludge build up.

Rads cold at the top indicate air in them.

Try waiting until all the rads are cold and the pump is off before bleeding them.

I don't understand what you mean by 'your husband put some air in the pressure tank' though

 

[gita patel]

Because the water was overflowing from the overflow and I though the pressure in the pressure tank was low. When pressure low the water does not stay in the tank. It leaks out in the overflow.
but I found out later that the water in the overflow was coming from the main water tank.

Thank you for your help I will follow instruction you have given me and will keep you informed.

 

[JohnD]

When pressure low the water does not stay in the tank. It leaks out in the overflow.

I think you've got this the wrong way round.

When water escapes through the "overflow" (actually the pressure relief valve) then it causes the pressure to drop.

If the PRV has been letting water out then it is likely not to seal tightly again and will continue to leak a bit unless replaced

can you post a pic of the radiator bleed nipple so i can see what you mean about difficult to get at? Also please show a pic of the other end of the rad.