Radiator needs regular bleeding

[phj]

One radiator in the house needs to be bled every week, it works fine otherwise and there is no sign of a leak near the radiator or in the pipes leading to it. Should I be worried about a leak?

 

[Ben-gee]

Is it upstairs?

There is probably a leak elsewhere on the system and this radiator is where the air accumulates.

It wants sorting out, need to find where it is losing water.
Is the pressure relief valve on the boiler dripping outside for instance?

 

[phj]

Yes it's the towel rail in the bathroom upstairs. There is a layer of dust on the pipes around the relief valve so no dripping there. I've looked at all the pipes I can see, but some are underneath floorboards and fitted carpets upstairs!

 

[SJB060685]

Is this an open vented system (tanks in the loft), or a sealed system?

 

[phj]

There's a header tank in the loft on top of the cold water tank

 

[SJB060685]

Ok. Is this a new problem or being going on for some time? Are you sure its air and not hydrogen when you vent the radiator? Hydrogen will have a rotten eggy smell.

 

[John.g]

Tie a plastic bag of water under the vent to see if its drawing in air, this sometimes only occurs when the circ pump starts or stops.

 

[phj]

Ok. Is this a new problem or being going on for some time? Are you sure its air and not hydrogen when you vent the radiator? Hydrogen will have a rotten eggy smell.

Probably several months now - it smells of rust - and the water that comes out after the air colours the pot that I catch it in rust colour
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Tie a plastic bag of water under the vent to see if its drawing in air, this sometimes only occurs when the circ pump starts or stops.

The vent is on the top of the radiator!

 

[John.g]

The vent I am referring to is the one, a 3/4 ins copper pipe, that goes up and over and is then bent down over the header tank, if you just immerse that in a plastic bag of water taped or tied to the vent pipe you will see over a fairly short period if its drawing in air occasionally as the water will disappear out of the bag, you could just hold a beaker of water under it with system running for a quick test but this is inconclusive unless the water level starts falling immediately for the reasons given in post #9.

 

[phj]

The vent I am referring to is the one, a 3/4 ins copper pipe, that goes up and over and is then bent down over the header tank, if you just immerse that in a plastic bag of water taped or tied to the vent pipe you will see over a fairly short period if its drawing in air occasionally as the water will disappear out of the bag, you could just hold a beaker of water under it with system running for a quick test but this is inconclusive unless the water level starts falling immediately for the reasons given in post #9.

Sorry, my mistake! OK I'll give that a try.