Last Rad On Combi Problem...please help...!

[Beans-on-Toast]

Hi There
TIA for any help.

The combi feeds 6 rads on the loop, the last one is in the living room and by far the largest rad in the flat. A couple of months ago the l/r rad went cold. I then found for whatever strange reason the installation was completed with the last rad being fed by 10mm wheeras the rest is 15mm.

I have cleaned the radiator, changed the valves (including 1trv), the boiler is working fine, the hot water is fine, the central heating is fine, apart from the living room radiator, which is slightly warm on and around the trv, but the rest is cold including the pipe on the lockshield.

Any ideas would be appreciated as I am about to cause some major damage, getting to the pipes and getting shot of the 10mm feed.

Oh and I have also bled and refilled the system at least 3 times.

 

[kevplumb]

close the other rads down and then see if it heats up

 

[Beans-on-Toast]

I have and it warmed up slightly more, but no full heat....!

 

[JPC]

could be sludge

how old is the system...

how dirty was the rad u cleaned.

has that rad got a drain off valve ?

++++++++++++++++++++++++++++++++++++++++++

tried the pump on 3 ? with other rads closed to see if it shifts summit

 

[Beans-on-Toast]

I was actually amazed to see how clean the water is, that drains from the system and nothing came out of the radiator.

The system is 3/4 years old and did have a drain off cock on the living room radiatotor although this was above pipe level and ineffective so I replaced that with a lockshield and put in a drain off cock lower down on the system.

 

[JPC]

if ur boiler has the filling loop connected to return and u have a drain of valve on the flow u colud turn the boiler and run some water through the filling loop...to the problem rad (close others) and back up the return and out of a hose u have attched and to waste somewhere...

start it up slowly and build it up....this should clear it if it is a blockage.

or ir could be u have turned the rad valves down and not up or faulty one (but u said they were new ?)

 

[Beans-on-Toast]

Sorry, I'm not with you, to what waste somewhere....?

 

[JPC]

a sink ?

basically u are runing water through the pipe to the rad and back out the drain valve on the flow. this drain valve will be open and with a hose attached . aim the hose into a drain/sink that way u get a loop of mains water runing through. this might clear it if indeed it is a blockage problem

 

[Beans-on-Toast]

OK, I have done that blown the rad through, refilled the system and hey presto...........................

the rad is still cold.......

Any Ideas Chaps.........? ? ? Please, TYIA.

 

[JPC]

pump on 3 and other rads closed ?

did much muck come out when you tried the previuos ?