Hi,
The twin entry valve could be your problem.
In my experience these are not very good & sometimes cause a lot of
problems.
There is an injector tube that comes from the flow of the valve & runs
along inside the bottom of the rad. This is so that the hot water is
delivered to the far end of the rad, away from the return on the valve
if you follow what I mean.
Quite often this injector pipe comes off inside the rad, the result is
as soon as the hot water reaches the rad it is away again down the
return, so the hot water isn't circulated through the rad. However you
should still be able to feel some heat at the valve end of the rad.
I have only ever seen this type of valve used on 8mm pipe.
If you have no heat at all in the rad or the pipes going to the valve
of the rad then you have a blockage. This could be in the injector
pipe
inside the rad.
So remove the rad & flush it & check the injector pipe is there & not
blocked.
If you have flushed out the rad & still you have no joy try doing this:
Get hold of the tail part from a rad valve (the part that screws into
the rad) Connect a hose pipe to the part that would normally screw into
the rad &
this will then connect to the rad valve to allow you to flush the valve.
With your problem rad removed connect the tail to the rad valve.
With the hose pipe on the cold tap open the flow side of the valve &
then open the tap. If you here water movement, the flow pipe is
clear.
Have someone watch the header tank, as the level in it should start to
rise if the pipe is clear & the cold water from the tap is forced into
the heating system.
Do exactly the same on the return side of the valve, but remember to
close the flow you have just done.
If both pipes are clear & you have flushed the rad when it was off it
should work ok when reinstalled.
HTH.
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Thanks - I will be trying it at the weekend. One pipe is slightly warm - but
the return isn't. I suspect there is a very slight flow and the heat is
quickly dissipated.
I was thinking of:
Place bowl under drain cock at opposite end of radiator - close valve and
lockshield screw.
Open cock then observe flow from the drain with either the valve or the
lockshield open. This should show which pipe is not giving much flow.
Connect mains water to radiator - open the valve which has indicated a
restriction and back flush.
My concern is that the blockage may not yield.
I will probably take the radiator off (easy but messy) to check the nylon
injector tube.
Thanks.
--
Regards
John
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