my current system was installed in the late 1960's and I believe is called a single pipe system fed by a OIL TRIANCO boiler. I am changing to a GAS boiler and have been advised that I may need to re pipe the whole house heating circuits. Is this the case?
Well maybe. The problem with a single pipe system is that it is hopelessly inefficient. It would be wise at this stage to update the pipework so as to ensure that all the radiators can be balanced properly and you can take advantage of the modern boiler's high efficiency.