Chris
Don't mean to sound disrespectful but your rad system is not (should not) be connected in any way to your washing m/c.
Your washing m/c does not call water, hot or cold during the spin cycle.
Your machine might be knocking the pipes or even throwing the rubber connecting hoses around a little during the spin cycle and this would travel throughout the whole house if the noise is transfered to the water system.
A little noise goes a long way through water.
try pulling the machine out of its cubby hole and running a cycle with it sitting out a bit remember though to make sure there is good flow through all your hoses, (NO KINKS) a washing m/c emptying onto the kitchen floor isn't funny, been there done that.
kennyf
March 2009