Drain down system with return above lowest rads

[brokeitself]

Hi All

I'm planning on doing some work on my CH as it's been out of use for a while and full of sludge but I have a bit of a dilema with how to drain down due to the system design

I have an Ideal combi in an above worktop cupboard with the return pipe running upwards behind the boiler up through the ceiling, the pipe is fully enclosed behind the boiler bar a few inches between the top of the boiler and the ceiling.

I want to drain down to replace some rads and cut away the return pipe and re-route it to install a filter but with the boiler sitting well above the lowest rads and the return going up not down even if I drained all the ground floor rads I'm still going to have at least 2+ meters of sludgy pipe that I don't want running through the boiler.

Is it possible to drain down from the boiler return valve fill loop connection for example is it a non return valve and is there any other reasons why this shouldn't be done, I have ordered a hose adapter to try it but I won't be back to try it until saturday.

I do have a drain off on the CH flow pipe but in my head if I drain in that direction I'm just going to run all of the sludge through the system and probably kill the boiler as the rads aren't in great shape.

thanks

 

[brokeitself]

Sorry to bump this one as i'm popping back on saturday and aiming to get my family moved back in next week and the rads have sat for a couple of years without being used.

Does anyone know if a return valve on the combi can act as a drain off through the filling loop (flexi hose) by removing the inlet side or straight from the valve with a tap connector.

In my head this should work but I know there has to be backflow prevention regs on boilers which makes me think that the return valve might be a non return valve