Central heating header tank

[shamstar]

Hi all,

I have a vented central heating system made up of:

Ground floor:
Potterton floor standing boiler (very old but still going)
3 radiators (there were 5 but 2 were removed some years ago)

1st Floor cupboard:
Hot water cylinder (less than 3 years old)
Grundfos UPS 15-50 pump (next to hot water cylinder) - On looking at this closely it has been on setting no 3 since installation.
Honeywell 9124 (electro mechanical theromstat connected to the hot water cylinder) - no idea how old or what this actually does!
Control panel for hot water and central heating with basic timer
4 radiators

2nd floor
5 radiators

Attic space
large header tank supplying water for the cylinder
small header tank for central heating

The problem:The radiators on the second floor need to be bled every year around Sept/Oct to keep everything nice and warm. Unfortunately this hasn't been done for past 2 years and now when the boiler fires up for a few mins, the rads on the ground floor get hot, followed by loud clanking noises from the pipes in the hot water cylinder cupboard and then the boiler goes to pilot light only. This is clearly caused by lots of air in the system. I have tried to bleed all the rads starting from the 2nd floor. Nothing happens - I use a rad key and loosen the bleed nipple and no water comes out - only small amounts of hissing air from one or 2 rads. I have tried to bleed all the rads with no success. I can even remove the bleed nipples fully from all the rads and still no water will come out. My plan was to drain the system down using the lowest point, close off each rad and then fill the system, hoping to force the blockage out, unfortunately the header tank stays full - doesn't call for any water and so I now have a full header tank and empty rads with each day getting colder. All the rads have had their vales closed off ready for the refill and individual air bleed.

Any ideas? What can I do to get water to flow from the small expansion tank - the float is working fine, as I have pushed down on it and excess water started to fill into the expansion tank.

Please advise

Shamstar

 

[Dotty]

You've a blockage caused by a build up of sediment on the make up pipe. Unless you're confident enough to repipe where necessary you should call someone in.

Whereabouts are you?

 

[Billy Bob Bob]

sounds like the neutral points blocked or ballvalve jammed if no water going into the system

 

[bspareltd]

your cold feed could be blocked , also have a look at the pump because it looks like your boiler is overheating due to the heat not being dispursed,if the pump is fine.

Back fill the system and it should be fine , if blockage is extreme and add some fernox feroquest , but beware could cause leaks in weak and corroded radiators.

 

[shamstar]

Hi, Just a quick update!

Thank you all for your help it was the cold feed from the header tank going into the cylinder cupboard;the correct pipe was identified by me tapping up in the loft as wife felt the pipe in the cupboard!

I would upload a picture but couldn't cope with the shock reaction to my awesome soldering! Haha! My wife just looks -shakes her head :hurray: says don't quit the day job! =P
We are a happy warm home.