hello
our plumber put some descaling fluid in the downstairs rad in our house a few weeks ago, cant remember what it was called, maybe a specialist plumbing supplies will know the stuff. It was about a litre and he unscrewed where we vent the rad and syphoned it in using a syringe, we have a baxi and pump was renewed earlier this year, but was very noisy and sounds of water gurgling all the time, anyway after the descaling didnt vent for 2 or 3 days as advised now working a treat and soooo quiet
pat
December 2005