New radiator not heating up

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Hi

Full disclosure, I'm not a plumber (or any kind of trade) but an enthusiastic DIYer with moderately good skills.

In my first attempt at a 'proper' plumbing job, I've changed an ugly old radiator for a nice new vertical one - in case it makes any difference, it's a Milano one from bestheating. I forget the exact model, but it's single flat panel with four sections. It's around the same surface area as the old one (which worked fine), just vertical.

I piped it all up in summer, new TRV and lockshield, no leaks, seemed to start heating up, so I thought all was good and left it. Now it's getting colder and the heat has gone on, it turns out the radiator warms up slightly and relatively evenly, but it's not hot at all.

I chased the pipes behind the wall while I was at it, so there were some minor adjustments to the pipes with new pipes, but just to get them behind the wall and to the new valve locations, I followed where the previous pipes were. There were no leaks.

The flow pipe heats up nicely and the return is warm, but not hot. Below are the things I've checked/done:

- bled the radiator several times, there is no air;
- the pin in the TRV is not stuck;
- the lockshield has been put at several points including fully open with no difference;
- I didn't remove the bleed valve from where it was when it arrived, so I don't think the radiator is upside down;
- all the other radiators still heat up properly;
- we had a combi boiler fitted when we moved in in Dec 2023, at which point the system was flushed and no problems since, so I'm assuming there's no blockage;
- the boiler doesn't seem to be losing pressure.
- we have the same but slightly bigger one in the kitchen (fitted by a plumber when having a new kitchen put in) which works fine, so I'm assuming it's not an inherent problem with the model.

After the fact I've read somewhere that these radiators should have a baffle that sometimes doesn't come fitted, but I didn't think to check at the time as I didn't know. I just wondered if I've missed anything obvious to those in the know before I start taking it off to check if there's a baffle!

Thanks
 
Have you turned off every radiator except the new one you fitted. See if it heats up
 
As above turn every rad off apart from one playing up and have lockshield fully open
 
Thanks, I'll give that a go and see what happens - I'm assuming that's to see if there's an issue with the radiator or some wider problem?
 
Thanks, I'll give that a go and see what happens - I'm assuming that's to see if there's an issue with the radiator or some wider problem?
it pushes any air locks in the rad or pipework out of the way
 
It could be the baffle. I’ve not fitted any of these, but believe they can be fitted the wrong way causing it not to heat up.
 
Thanks, I'll give that a go and see what happens - I'm assuming that's to see if there's an issue with the radiator or some wider problem?

No, it's to force water through, ensuring there are no airlocks in that section of pipework.
 

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