Double radiator with varying temperatures.

FreeBear

akira181 said:

FreeBear said:

Balancing of radiators is important regardless of the size of the system.

I suggested cracking open the lockshield based on experience  One of the radiators here that I balanced and adjusted to give a ~10°C temperature drop only ever got warm at the top. Cracked the valve open to give an 8°C drop, and it now gets well toasty.

I'd suspect that your rad either had a minor bit of sludge restricting the channels at the bottom or the lockshield was too restricted to begin with. Both cases, opening the lockshield would fix it (until the sludge built up some more in case of the former) but that's just my guess without knowing your system.

Brand new radiator, so zero sludge in it.

Rusty190

Just revisiting to update and get further views.
Plumber returned and situation discussed.
He turned off all radiators, except this one, and cranked up the heat to Sahara desert level.
Cue, 1 piping hot radiator - both front and back panels top to bottom.
He let it run like that for an hour or so then turned on rest of radiators.
All good - everybody happy.
He suggested it may have been trapped air as he could hear some gurgling in radiator.

Following day - back to how it was ie, cooler bottom than top, tepid bottom back panel.
Been like this since.

If it was sludge, would it have heated up properly when it was the only one running?

Any thoughts gratefully received.