Central Heating Problem

[Paul Fox]

I have a house with 18 rads,and some of the rads are not getting hot at all.I have changed the pump to a larger one but still no joy.I can feel hot water at the infeed pipe to all the rads but it will not circulate on the rads down stairs.
Does anyone have any ideas please.
Has anybody ever put two pumps in a system,one for pushing the hot water round on the rad feeds and one for returning the water to the boiler.

 

[oldbuffer]

If the downstairs radiators are fed from upstairs I'd suspect air locks as the first possibility to investigate.

 

[wwwebber]

Turn off all rads except one and check that it's heating up and bleed it too. Then turn off and move onto the next one etc etc. This should flush out any air lock. Just ensure that you don't close all rads at the same time for safety reasons.

 

[MeldrewsMate]

Did you check for stuck-down TRV pins before buying that expensive pump?

 

[Doggit]

Define slightly better when you say, some of the rads aren't getting hot. How many of them; all of them upstairs or just downstairs. The the rads that work get hot enough.