Cold radiator (microbore maxitwin system)

[mangroa]

One of my large rads under a bay window is not getting hot these days.
Its warm at the top, but the bottom half in the middle is always cold. The warm parts are not as warm as other rads in the system. The valve and pipes into the valve do feel properly hot.

Last week I drained the system and added X400 sludge remover and ran it for a week. Today I drained the system, removed the rad and flushed it in the garden.

After refilling, bleading etc the rad is no better. There has always been a small kink in the 8mm pipe leading to the rad so that may be a cause.
Its a Maxitwin system with both pipes entering the rad at the same end.
I forgot to properly check the state of the internal pipe that injects the hot water into the rad. I'm wondering if that could be loose. It didnt fall off when removing the rad, and I never looked more closely at it. I assumed it would be secure and not let water bypass the rad.

I think my options are:
1. Drain again and check internal pipe incase its just loose and letting water bypass the rad.
2. Get rid of the maxitwin valve and route some 8mm pipe to the other end of the rad. This would also get rid of the kink.

If I choose option 2 will it be ok that the rest of the system has maxitwins and just 1 rad has separate flow and return valves?

Any advice???
Thanks
Alan

 

[namsag]

If you have manifolds on the flow and return this is probably where the blockage is.

Perfectly ok to have some rads twin entry and others either end..

Take rad off again and open valve to see which pipe is blocked you should see a difference

 

[mangroa]

Thanks for the quick reply.

I cant remove the rad without draining the whole system. The valve only shuts off the flow, and not the return. It doesnt have the little cap with the screw to shut off the return. Next time I drain the system I'll install a new valve with the screw to shut off the return.