Weekly radiator bleeding upstairs and one cool rad

[headache5678]

At the highest point in my house, I have one hot radiator that needs bleeding weekly if not daily and at the lowest part of my house I have a radiator that gets lukewarm at best. All other rads work fine.

I have a conventional CH system installed in 1985 which is not combi and has a hot water cylinder and expansion tank i.e. it is not directly mains fed.

In the spring, my plumber drained, flushed, refilled then balanced the system to get rid of cold spots.

I wonder if there is a connection between the need to bleed the higest radiator whilst the lowest is lukewarm at best ?

Is there any kind of treatment / gunge that I could safely put in my system (how, using a syringe in the bleed screw hole ?) that might seal the "bleed-needing" radiator as the plumber was not able to fix it, but charged me.

 

[Burnerman]

Continuous bleeding is likely to be due to a build up of magnetite (rust, if you like) in the system...this stuff produces its own hydrogen gas and its that which you bleed off. The cool rad may be due to a balancing issue - unless the circulation is hindered by the aforementioned dirt. Check that the flow and expansion pipe in the loft has about 4" of water in it. You can certainly inject inhibitors through the bleed valve hole, but the system needs to be clean first. John

 

[headache5678]

Thank you - I will try this. I guess there is no glue like stuff (like Radweld used in car radiators) that is safe to use ?

I have just removed, flushed and replaced the "cool" raditor and the water was clear as a mountain stream.

Cheers
Kevin

 

[Burnerman]

When you removed the cool rad, did you open each valve in turn, allowing some water to escape? Its possible that there is a blockage or airlock, which occasionally can be very awkward to shift. As the hot water flows around the heating circuit it always follows the easiest route so it could be bypassing that one rad. Try turning some of the good rads down and see if this one heats up. If it does, the system needs balancing...plenty of good info in the Tips or FAQ section.
I'm not sure about what you mean by introducing some chemical to the rad that needs bleeding...the air or gas has to be stopped being produced for the bleeding need to cease. I'd be very surprised indeed if there wasn't some muck in the system somewhere...there always is!
Best of luck, cheers John

 

[JohnD]

can you do basic DIY plumbing?

does your system have a Feed and Expansion tank in the loft?

do you know where the drain cock is?