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lemo · Joined: 01 Dec 2007 Posts: 8 Location: West Sussex

Having trouble bleeding the air from my rads. Small header tank in the loft is full and i have managed to fill the downstairs rads.
Gravity appears not to be working for me on the upstairs rads though as no air hisses out when i try to bleed each rad. Even the pump appears to be dry as when i turn the big screw on the front no water dribbles out.
Now i'm at a loss as to what to do next,any help would be much appreciated.
System was working fine before and all i've done is drain it to get the fernox cleaner out. Confused

thescruff · Moderator Joined: 03 May 2003 Posts: 4755 Location: Bath

Sounds like you may have blocked the cold feed.

Stick a magnet on the feed pipe where it joins the system.

lemo · Joined: 01 Dec 2007 Posts: 8 Location: West Sussex

Thanks for your reply Scruff,
I was a bit sceptical about trying the magnet but i did anyway whilst looking over my shoulder for the candid camera!
It didn't appear to have any effect and i presume that this is the small copper canister which is connected to the feed from the header tank and also the expansion vent this sits in the airing cupboard above the pump?
I have since gone to plan "b",and connected a hosepipe to the ground floor radiator drain off. Using the mains pressure i filled the system whilst bleeding the upstairs rads. The water then started to emerge from the vent pipe on the header tank.
I fired up the boiler and all the rads are now getting warm.
My only worry now is that the original problem may still be there and the header tank with all the fernox inhibitor in it is not doing its job and getting round the system?
Sorry this is a bit long winded but its a bit difficult to explain,any more thoughts?

thescruff · Moderator Joined: 03 May 2003 Posts: 4755 Location: Bath

Yes, The cold feed is blocked.

If you follow the pipe down from the tank, when it joins the system is where it will be blocked.

The magnet trick is not a trick Laughing

, it will stick to the magnatite in the pipe

lemo · Joined: 01 Dec 2007 Posts: 8 Location: West Sussex

Right magnet attached,
How can i tell if its making any difference and will the small copper cannister need replacing?
I presume this cannister also acts to remove air from the system somehow?
It is "soldered" into the system,am i starting to exceed my plumbing "skills"? Should i call in a man that can and stick to being a sparky Laughing

ITPC · Posted: Sun Dec 02, 2007 12:07 pm Post subject:

The magnet will not cure the problem, it will just show you where the pipe is blocked if it is blocked with the magnetic form of iron oxide.

lemo · Joined: 01 Dec 2007 Posts: 8 Location: West Sussex

Aaah i see Idea

,
I'll give it another go now the penny has dropped Smile

The tank did have a small amount of sludge in the bottom and apart from me adding the fernox cleaner two weeks ago has been untouched and running fine for about 8years.

lemo · Joined: 01 Dec 2007 Posts: 8 Location: West Sussex

Well i've had another "play".

Part of the pipework does feel slightly magnetic,especially around this cannister where the feed from the header tank comes into that i keep going on about.
Is this something that the cleaner should of removed or is it a bit more
serious and need the pipework replacing?
It managed to drain ok the 1st time which why its confusing me a bit,
cheers for all your help.

thescruff · Moderator Joined: 03 May 2003 Posts: 4755 Location: Bath

Replacement is the norm if you can't shift it.

What probably happened was you have dragged all the sludge out of the tank when you drained it.

lemo · Joined: 01 Dec 2007 Posts: 8 Location: West Sussex

Cheers guys

Many thanks for your time and all of your help,much appreciated.
May leave it running for a while and see if it clears on its own.
At least i've got the heating back on again and the rads are bled.
Phew Exclamation

thescruff · Moderator Joined: 03 May 2003 Posts: 4755 Location: Bath

You may be able to push it back out with the hose pipe if you're careful and Temporary cap the vent

Boiler must be cold and off.

lemo · Joined: 01 Dec 2007 Posts: 8 Location: West Sussex

So if i let it all cool down and do as i did before with the boiler off and connect the hose on to the downstairs rad drain valve,blocking the vent.
This would stop the water coming back out of the vent as before and force it back up the header tank feed.
I see where your coming from,will have to try it tommorrow now as i've got a nosey nine year old son with sticky fingers Smile

thescruff · Moderator Joined: 03 May 2003 Posts: 4755 Location: Bath

Could just work but don't take the pressure above 2.5bar

lemo · Joined: 01 Dec 2007 Posts: 8 Location: West Sussex

Hi all,

Thought i'd let you know the outcome of my heating 'saga'.
The copper vessel i was referring to is apparently a water agitator,
these were all the rage in the 70's/80's.
This had blocked with all the sludge when i had drained down the tank.
It seems they can also be more problematic than they are helpfull by actually drawing air in when the system is unbalanced (boiler starting up).
All is sorted now as we cut this out and just joined the two 32mm pipes together,doing away with the vent pipe and putting in a tee to connect up the header tank feed.
Thanks for all of your help and advice guys,much appreciated,

Lee