Central heating problem some radiators cold?

Question

Oil fired central heating system, with a feed and return pipe, house bungalow, rads at front of house heat no problems, warm water heats no problems but rads in the three bedrooms only heat a little at the top, flushed rads out, no change and there is a gurgling in the pump and boiler, the three rads that don't heat properly, the feed pipe is roasting but it seems the water can't get throught the rad, all valves open, return from these rads luke warm, I beleive theirs air in the system on the return pipe restricting the flow, but cant shift it no air in the rads

Answer 1

Bleed all the Rads

Answer 2

Ok. First bleed all the radiators, but make sure the central heating is off. This probably won't make much difference, but it's something that you have to do before you invest time and effort in the next stage. Next, shut down the good radiators one by one until you get some heat from the poorly performing ones. If they heat up then that's good news. restore the flow in the ones you shut down by opening the valve a quarter of a turn at time. This process of balancing the flow of hot water between the radiators is quite time consuming, but you'll get a result eventually.

Answer 3

Have you tried bleeding them with the wee key? Do the one furthest away from the boiler first - that should get rid of the air that's probably causing some of them to be cold. Hope this works.

Answer 4

sounds like the system needs bleeding

Answer 5

if it's a pressurised system, if might be low in pressure