Leaking rad, Dunshaughlin area

[Male Doon]

Anyone know a good plumber who can fix a leaking rad? We've had two who attempted a repair but didn't solve the problem. It's not a severe leak but over time it is affecting the level of water in the heating system and adding new water, AFAIK, dilutes the additive that was put in when we had a new boiler installed last year.
Thanks in advance for any help...

 

[DGOBS]

Where is it leaking from?

 

[Male Doon]

Where is it leaking from?

Leaking from the base of the on/off valve so that the water drips down the pipe going into the floor (the rad is in an upstairs bedroom)...hope this clarifies...

 

[DGOBS]

Drain system and remake fitting is required, or you could try draining one rad and adding something like
sentinel leak sealer