Flushing Central Heating pipe work and radiators

5 Feb 2021
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United Kingdom
Hello all.
I have a combi boiler and heating pipes have manifold upstairs. I want to flush heating system and radiators but do not want to touch valves on boiler in case they start to leak.
To save taking off all radiators could I take off one side valve from 1 radiator. Turn flow / return off to all others then on the radiator with valve removed open flow and return seperate and use filling loop to flush out pipe and radiator. Then repeat around all radiators.
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Can you not remove each rad, take them outside and flush them out with a hose outside? Give them a good shake too, to break up the sediment.
You can really only do that on the side that the filling loop is connected to. If the loop is on the return then you need to take off the flow side valve and then open the loop, that'll send water down the return into the rad and out the open valve.

As far as shutting of the boiler valves, you really don't want to flush anything from the pipes/rads. You could disconnect the flow and return and then connect a pipe to them and run it outside/to a sink/toilet etc.
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Thanks for replies.

Would water still not be able to pushed into return from full loop then go down flow that’s open after passing through manifold?

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