DIY Doctor UK DIY Forums

Please can somebody tell me the best way to drain and flush out a central heating system which is fitted with a combi oil fired boiler?

Why ? it depends on why it needs flushing - to decide which way would be best.


htg

The system has been in service for 10 yrs now and to my knowledge has never been flushed out. The system is working ok but having recently taken a radiator off the wall to paper behind it, found that the water that came out of the radiator was really quite black. I just assumed from this that it needed a clean out.
many thanks for replying

Alistair

if it's black water and not thick black sludge, then there's no need for a powerflush (saves alot of money).

You can either remove all radiators and flush outside with a hose pipe. Then all you have is the pipework to drain and refill a few times until the water is clear.

or

Add a system cleanser, leave in for the recommended time, drain whole system, refill and drain until water runs clear.

Either way the only way to completely remove all the rubbish is to remove all downstairs radiators (Upstairs will empty when drained from somewhere downstairs) downstairs radiators will remain full unless the pipes feeding the radiators come up from the floor and there's a drain point below the floor.

Once you have the whole system filled with fresh water, don't forget to add inhibitor, if this is added and replenished everytime the system is drained, it'll probably never need flushing again.


htg

Many thanks for the advice. it is black water and not sludge so I will not have to power flush.
I will add a system cleanser and do it that way.
Many thanks for the advice.

regards
Alistair