Anyone know anything about radiators?

One of our rads isn’t getting hot, but all the rest of them are.

I’ve bled the cold radiator and it seems fine, but there is no hot water in the pipe leading to or from it.

It is fed from a radiator upstairs, the pipes to that one are both hot – so I guess that radiator is fine?

Could this be a block in the pipe? If so how do I fix it? It’s all boxed in.

It’s the dining room one on my architectural plan.

Has it ever got hot?  are both valves wide open?

Try turning the valves off on all the others and see if that forces hot water into the cold one – could be an air lock.  IMO a blockage is unlikely unless its small microbore pipe

I assume the rads are all in parallel?  some in your drawing appear to be in series

Could be a blockage, could be a lazy rad that needs balancing properly.  I’d turn off the valves on all the other rads 1st and see if any heat goes to the problem rad, this will rule out any blockages.  You can then bring the others back ‘online’ one by one.

Thanks both. Rhe bedrooms are first floor, the ground floor rads are directly underneath.

I’ll turn them all off now…

Make sure your trv s are actually working, I had same problem last year, the pin inside was stuck inside, so no amount of turning trv was doing anything.  So 1 failed, I then tried others and they were all the same.  Just wiggle pin in and out manually see if there’s any movement.

Yeah, turn all the others off and it will hopefully push heat to the one that’s not on.

Make sure your trv s are actually working, I had same problem last year, the pin inside was stuck inside, so no amount of turning trv was doing anything.  So 1 failed, I then tried others and they were all the same.  Just wiggle pin in and out manually see if there’s any movement.

My money’s on this.

Trv pin may well be it. I had this issue last year. Simple way to check is just remove the trv completely (unscrew) and see if sorts

Stuck trv as others have said, take the top off and push the pin up and down repeatedly with something smooth and metal until it’s free.

One of mine did this recently in a spare bedroom. TRV seemed to be ok, I opened the lockshield half a turn and it been fine since.

Something must have happened because it was fine last time the heating was on regularly.

Maybe some scale or an airlock? Either way, a bit more flow through the valve fixed it.

We had a cold radiator which the valve was stuck closed after some work and needed changing. Then we had a coldish radiator which were about to replace and then tried balancing the radiators. It actually worked and now a super hot.  Could be worth a shot

The tap/valve things are usually plastic. So maybe its become worn and is turning, but not turning the metal part and just spinning.

I had a radiator that had never got anything near luke warm; at best the inlet tail would get warm (not hot)

tried everything, flushed the rad, new rad (as part of a relocation so not completely wasted)

multiple system flushes etc.

turns out the genius who plumbed it in had taken the inlet and outlet to / from the rad to the same 22mm central pipe. Muppet