OLD ONE PIPE SYSTEM? QUERY?

[novascotia]

My parents have an old one pipe system , and teh flow to each radiator is in at the top of each rad- some being new rads and some beign old cast iron rads. The return comes out of the bottom opposite corner.
They want a new combi in and have been told that the rads will be ok left as they are for the new "2-pipe" system. Is this ok and also why was it like this in the first place.
any answers will be greatly appreciated
all the best

 

[Bahco]

Advise to renew complete system, changing to a more efficient two pipe system.
It will avoid flushing your old pipework and rads of magnetite which if not done thoroughly will damage your new boiler.
One pipe systems are also not very efficient.
Good deals to be had at the moment if you consult local Corgis in your local paper but opt for a good boiler such as Valliant or Worcester Bosch (or Ravenheat ONLY JOKING)