Fixing Central Heating Radiators?

In article , the_constructor writes

There are marginal efficiency differences between the different radiator feed configurations, TBOE (Top Bottom Opposite End) being the most efficient(*) and BBOE the least, with TBSE (Same End) somewhere in- between but I think it's only a couple of percent between best & worst. Having the TRV at the top is more grapper friendly as it is easier to adjust.

(*) but only if you feed flow (hot) to the top

I was wondering does top & bottom piping have any bearing on the radiators being bled ..... ?

-- the_constructor

If they are thick pipes and an old radiator, it might be gravity fed, which requires inlet at top and outlet at bottom (and even if it isn't gravity fed anymore, it might have been originally).

For a pumped system, both at bottom or inlet at top outlet at bottom are fine. If you have a multi-zoned system, both at bottom will prevent a cold zone cutting in from emptying the hot water out of the other radiators -- when the circulating water goes cold, it just runs across the bottom of the already hot radiators. Both at bottom is probably quieter if you did happen to get air in a radiator too.

In article , the_constructor writes

Good point, I've done mine as BBOE and mounted the rad level. I then put a level on the completed beast to see how far out it is ;-), and put the bleed valve at the high end.

In theory I don't think it matters unless you have the rad a mile off level & have the bleed at the low end as the bleed takeoff point is never absolutely at the highest point in the rad and so there will always be a minute amount of air about.