bleeding rads

[sally1967]

i am having to bleed 3 rads once a week but all my others are fine,8 others in total,the 3 that need bleeding every week are the 2 towel rail rads and a downstairs rad.why am i having to fill these on a weekly basis and not the others ?

 

[Bahco]

It sounds like you have a leak on that "drop".

Is the rad below the 2 towel rails

 

[sally1967]

yes the 2 towel rails are above the rad and there is no water leaking that we can see so what do you mean by a leak at the "drop"

 

[Bahco]

Are the towel rads directly above the problem rad?

For example if the draincock was opened under problem rad and the towel rads drained too then you will know that the leak is on that run.

Check valves , joints etc.

 

[sally1967]

the towel rads are directly above the rad but no valves or joints ar leaking water as i have no wet floors or ceilings and no water present on the pipework and i dont know if the bottom rad is losing water before the 2 towel raails are losing theres as i am filling them up at the same time starting with the highest first

 

[sally1967]

could it be that my rads get too hot and that the water is evaporating and the system isnt re-filling them,thats if the system should re-fil them.

 

[having_a_gas]

It may not be air you are bleeding but hydrogen produced by an electrolytic reaction between dissimilar metals.

To test, hold a jar above the vent whilst releasing some gas, Light a splint then blow out, see if it re-lights when placed immediately into the jar.

If this proves to be the case the system will need chemical cleansing then an inhibitor added to the system.

 

[sally1967]

if it is hydrogen in the pipes is it a costly thing to eliminate it and prevent it from comming back.i will try the test on sat morn as ive bled them again yesterday.would this also account for the noises i get from the central heating system and a couple ofthe rads.