non draining c/h header tank

[Martin1962]

hello. Could someone advise plse?
I'm trying to drain and flush my c/h system. It's an open one, not sealed.
I've drained the radiators and checked that each one is empty by openeing the valve at the bottom of each one (where there is one.not all the ones upstairs have one) I stopped the header tank from refilling by tying up the ball cock.
I'm pretty sure the rads are all empty now, but there is still a lot of water in the header tank? I was expecting this to empty so I could put the flush in here and refill again.
What have I done wrong?
many thanks in anticipation.

 

[Agile]

Check where the outlet is located. Its often 60-80 mm above the bottom of the F&E.

If the outlet is still covered with water then the feed pipe is blocked.

Thats usually where the 15 mm feed meets the heating system 22 mm.

Cutting out and replacing the tube is usually the only solution.

The blockage is a complex calcium/carbonate/metal compound and very hard and resistant to weaker acids.

Tony

 

[theheatinghelper]

it does sound like the cold feed is blocked if its a fairly new system it could be just blocked on the way down from the F&E tank you may not need to replace what was said above..... first id get a compression straight ready15mm or 22mm depending on size of the cold feed ( or if you can solder thats even better) cut the cold feed 4-5 inches above where it joins the circuit .....if there is no water then the blockage is further up ...which ... if your after a quick fix ...get a metal coathanger straighten it and stick it up the pipe, have a bucket ready for the water that is left to come bombing out the pipe. once F&E is drained, blow down the end that goes into the system to make sure its also unblocked, if you can blow into it no probs then reseal the pipe with the compression or soldered straight fitting ..and hay presto! if this dont work repeat steps as per above post !!

 

[holty]

you could also try hooking up a mains feed e.g stoptap with hose, to one of the drains off, with jubilee clip.then put a removable stop end on the vent pipe.in doing so you might be able to shove the blockage,using mains pressure.

 

[Martin1962]

thank you to the three of you. obvioulsy, I was major league hoping that Tonys possible cause was not the fault! and i cant say that I really understood the clear instructions from theheatinghelper and holty (a "15mm compression straight"?? is deff double dutch to this stupid amateur ), but the idea of using mains water to try to flush thru from the feed in the F&E tank appealed to me. So I used a hosepipe and mains pressure....got a bit wet for a few secs, but I then heard it glugg and clear as it flushed whatever sludge had blocked the feed pipe and hey presto.....all clear.
many, many thanks chaps (or chapesses?)

 

[Agile]

You are very lucky that it may not be a hard blockage.

It may still be a hard blockage which has almost totally obstructed the pipe but the final few mm was blocked with soft sludge.

Regardless, you need to check the water in your system and if its dirty to treat it accordingly.

A badly sludged system is like necrotizing fasciitis.

Tony