3 out of 12 radiators not working - ideas?

I am a CH novice, and am trying to logically diagnose a problem befor

calling someone in, but am stumped...

3 radiators in one part of the house refuse to warm - even slightly. have:
bled all radiators > set LSV valves on all outputs (normal valves on input) > have tried multiple combinations of working radiators off (from al off to all on) > all working radiators are boiling hot, with good audible pum

pressure through them

non working radiator valves seem to be working as water will sqir

out when bled, and stop when valves turned off - BUT can hear no pum pressure when valves turned on or off

Only common factor of all 3 is that they seem to be fed from upstair pipes separately to other downstairs radiators which are fed from clos to the boiler.

There is only 1 pump and the normal 3 way valve.

Any ideas? I am reaching for the yellow pages now

-- nico62

Reply to
nico62
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Always been like this? Check layout of pipes.

Have gone like this fairly suddenly? Check water in header tank (not like to be a problem since the water squirts out). Possible blockage in common return or flow pipe.

HTH

Reply to
Ed Sirett

If you turn off all other rads and these still don't get hot with the pump running, then the water isn't circulating. Most likely an airlock in the pipes - water coming out of a bleed valve on a cold rad doesn't mean there isn't one somewhere else in the pipes.

If an open system, have you checked the header tank has water in it?

Reply to
Dave Plowman (News)

I was like that a few years ago. Now I probably understand my system better than a plumber :-)

Was the pump running when you did this? If so, you can not bleed the system. switch of the pump and try again.

Shut all the hot radiators down, don't use the lockshield valves. Make sure that the pump is not running. Bleed each cold radiator until you get a fair amount of water out of them (about a pint or so). Put the pump back on at its fastest setting, after closing 2 of the 3 rads that are not getting warm. This should pump hot water through the one radiator that is turned on. If this one gets warm, then turn it off and try one of the others, until you get them all warm. In my system, this can take a few tries to get it all up and running again, so don't give up on the first try.

HTH as I am no expert on central heating :-) Just my own.

Dave

Reply to
Dave

Do any of these rads have thermostatic valves on?

If so it is not uncommon for the valve bodies to "stick" in the off position... often you can tell by removing the thermostatic head with it's thumbscrew, and looking at the pin that is pushed by it. It should notmally be in the raised position and should be possible to push it into the valve by hand. It should spring back when released. If you find the pin is stuck down, you may be able to free it with a tap to the side of the valve with a (small!) hammer. In still no joy then replace the valve.

Reply to
John Rumm

I have exactly this problem if I drain my system.

I used the above technique plus the fastest pump speed I could get to clear the air.

Reply to
The Natural Philosopher

I'll give it a go and let you know how many attempts!

Thanks

-- nico62

Reply to
nico62

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