I've just replaced two panel rads with two vertical column Wickes rads. It's a combi boiler system and I've reset pressure to 1.5 bar and bled entire system, topping up pressure as and when. After bleed and repressurisation heating was turned on. All original panel rads heat up OK but new uprights are warm, but nowhere near as hot as panel ones, and heat is patchy. I read somewhere that verticals are flow sensitive and should have feed in on left btm, out on right btm, so this is how they are. I've heard from some 'these are brilliant' but from others' I can't afford any more plumbers bills to try to get them working'. I was also told of someone who fitted them wrong way up, they acted as mine are and they turned them over and all was OK but the way I saw it when fitting was side holes at top , for bleed and blank, bottom holes (upright entry) for pipework / valves and this is how those finished up and worked OK.
Any ideas
TJ