One radiator is completely cold - replaced it and still cold

experience · 11 Mar 2008

One of my friends rads stopped working & is completely cold.

So far he's replaced it with a new rad with new standard valves, both valves are fully open and the systems been bled. When the bleed screw is opened water comes out of the rad. Its supplied with standard 15mm copper tails.

The next thing i can think of trying is turning all the other rads off to try and force water to that rad - is there anything else we should try?

Bahco · 11 Mar 2008

Read FAQS post 8

Shades · 11 Mar 2008

It sound like you got air blockage in the pipe, try letting out some water from the system and then top it up again this may work.

experience · 11 Mar 2008

if it had sludge in the pipe surely it wouldnt refill with water once the system had been refilled?

Bahco · 11 Mar 2008

Bahco said:
Read FAQS post 8

experience · 11 Mar 2008

Shades said:
try letting out some water from the system and then top it up again this may work.

the whole system has been completely drained down and refilled

experience · 11 Mar 2008

Bahco said:
Bahco said:

Read FAQS post 8

Click to expand...

Looking at the FAQ the only things that i can see it could be are:
3) Air lock in heating pipe work (not radiators). Turn off all the other rads to force the flow into the cold one.
or
8 ) Sludge in radiator or pipe work or valve causing blockage which will need to be flushed out

One thing i'm unsure of from point 8 "make a fitting with a hose to attach to each valve" - any idea how i could attach a garden hose to a radiator valve - or any better ideas?

JPC · 11 Mar 2008

sounds like you have a blockage on one of the pipes..hence the rad fills up via the other, but water wont circulate due to the blockage.

Is is 15mm or might it be microbore...blocked manifold ?

is it a combi ? or open vented ?

does the rad in question have a drain off valve ?

you could resort to taking the rad off, attaching a hose to the rad valve (on the pipework) and opening up ( check where the water might go, ie open vented, or sealed....might need two hoses (entry and exit))

twgas · 11 Mar 2008

The next thing i can think of trying is turning all the other rads off to try and force water to that rad - is there anything else we should try?

pity you didnt try this first, if it works, it may have saved you a fair bit of time and money

MANDATE · 12 Mar 2008

Hi! I just dealt with a similar problem.
First removed radiator and checked water flow from both radiator valves.
Flushed out radiator while it was off.
Replaced radiator and found nothing had changed.
Did notice 1 rad cold, while another warm and another hot.
Then investigated further and found 'by pass' valve was fully open.
Adjusted this to about 1/3 open and all radiators then hot.
Problem solved? Not quite!
Few days later boiler kettling and found pump stopped.
Removed pump and found black crud had reduced the inlet and outlet down to about 3mm. (no wonder there was little flow)
New pump (and valves) fitted and all radiators now working fine.
Just needs a system clean and inhibitor.

experience · 12 Mar 2008

where is the bypass valve normally located - near the central heating pump? Is this normally fitted on a vented system?

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One radiator is completely cold - replaced it and still cold

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