Draining system down from Radiator.

7 Dec 2010
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United Kingdom
I want to drain my CH system down to see if it is clear, as I had trouble with a couple of rads not heating up during the winter.
The only drain point is on the hall radiator. If I drain from here the system will only be drained to the bottom of the down stair rads. If I then open the valve at the boiler to pressurise the system will that flush through all the pipework below the rads ?

Alternatively I could lift a floorboard and cut a pipe to allow it to drain into the space below. There's a good 18" below and it would only be the water from the low pipework.

Thirdly I could drill through the wall and fit a proper drain point off the low pipes but I don't want to involve myself in too much extra work unnecessarily.

Your advice will be appreciated.
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You made that all sound very difficult for a simple task. Just connect a hose pipe to the drain valve and let water from the refill flow through to an outside drain or something until it goes clear. Watch it as it flows and you will see the colour to know if it was bad. Just remember to add some inhibitor when filling back up. You could close all rads and open one at a time to watch the colour.
Thanks for that. Seems I've been thinking about it for too long!
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