Cannot get radiators to bleed

[Sprocker]

Hi all
I have a 25year old conventional boiler and I'm trying to bleed my radiators as a few are cold at the top and I'm not getting any water out. Just hissing. Just spoke to a plumber who advised that its sludge in the system and recommends replacing the boiler and a power flush etc.. I'm not to sure as im pretty sure I wouldn't have half the radiators working perfectly and the other half not getting hot at the top
If anyone has any advice tha TV would be great

Thanks

 

[JohnD]

im pretty sure

you're wrong, then.

Go up into your loft.

look for the "feed and expansion tank" which will be about 18"x12"x12". inside it will be a brass ball-cock as found in old WC cisterns. Above it will be a large copper pipe, in an upside-down "U" or "V" shape, with one end pointing down into the tank. (There will also be a much larger tank. This is irrelevant today.)

Is there any water in it? How deep? Can you see the hole in the end for the exit pipe? Is it above or below the water level?

How thick is the layer of mud at the bottom? (don't stir it up).

Later, you will have to bale this mud out into a bucket and tip it down the WC without any more of it getting into the pipes.

If you press down on the float, does more water squirt in?

To do the rest of the investigation, you will need a torch and a strong magnet (preferably neodymium)

 

[terryplumb]

If you have water in the f&e tank ,then you have a blocked feed.

 

[Harry Bloomfield]

Just hissing.

Is the hiss air being drawn into the radiator or blown out?

If it is blowing out, just wait until water flows out, it could take a few minutes.

 

[durhamplumber]

Later, you will have to bale this mud out into a bucket and tip it down the WC without any more of it getting into the pipes

Lol...good luck with that.

 

[durhamplumber]

preferably neodymium)

Jeez..

 

[Madrab]

If the radiator is bleeding (air hissing out when you open the bleed valve) then keep going until it either stops or water starts to run out.

If it stops hissing without any water, then as others have mentioned the feed is blocked, if water just trickles out then it may be restricted, either or, it will need a little pipework replaced. If it runs out ok then it's just been a lot of air in the rads.

 

[Sprocker]

If you have water in the f&e tank ,then you have a blocked feed.

What would be the best way to unblock if possible, I only need this system to last a couple more years if I can .thanks

 

[terryplumb]

Establish where the blockage is ,cut out sections of pipe / joints affected and renew. With the aid of a strong magnet ,running it along the feed pipe from the f&e tank ,down the pipe ,The first T Union is a common place for blockages to start. The magnet will be attracted to any blockage ,which is inevitability magnetite.

 

[JohnD]

Have you looked in the tank yet?

 

[ericmark]

In my father-in-laws house there was a problem getting the water back into the system, the plumber used a hose pipe on the drain and forced water in from the outlet. Not really the best idea, but it worked.

But reading what you say it would seem just not waited long enough for it to bleed.