Old systems worked on gravity hot water circulation and a pump on the heating.Usually if your radiators are getting hot and never did before it means one of two things.Either there is a non-return valve on the heating flow pipe from the boiler stuck open(can e freed with a thump if you can find it)...or the bad news ,there is a pipe fitted in the boiler which keeps the heating/hot water split(spreader tube).If this has gone its a new boiler or a controls upgrade.
As for the Hot water temp the only control you have is the boiler thermostat on the front of the boiler.Is this turned as low as possible?
Tom paris
May 2009