One cold radiator

[Gwenrose]

We have just fitted a new pump after suffering a very cold christmas with no heating.

Our system is up and running beautifuly, all the rads have been bled, all running well, accept one rad, it appears to be the last one and although we have bled it several times and been able to get hot water through ones, it is again stone cold, as is the pipes running down the wall to it and along the bottom.

There is no air in any of the other rads.

unfortunatly only three out of the seven have still got there thermostatic valves still intact, so we have opened the whole system up full and not cracked any down yet.

Any help on what to do next with the one radiator please?

 

[JohnD]

Unless you have a sediment blockage, the most likely cause is that the hot water is circulating freely through the other rads, leaving none for the last one.

To check this, turn the other rads off, and the last one should heat up.

Then, slowly increase the valve opening on the remaining rads, so that the flow is balanced, with none of them being cold or excessively hot.

Look up "radiator balancing" if this doesn't make sense.

 

[captain_pugwash]

i would say John is right and possibly there is an air lock in the pipe to this last radiator. I had same problem once. Shut off all the other radiators using the lock shield valves and this will have the effect of 'forcing' all the flow from the boiler to the cold one. Chances are that if you then open the bleed valve yu'll then get plenty of fizzing and gurgling until all the air in the loop is pushed out.

If it gets hot then balance the rest of the rads by gradually opening up their lock shields until all are hot together,